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Updates.Helpful ideas for setting up a small blacksmith's pneumatic forging hammer.
[Home] [Back to Air Hammers page] [Photos of STC-88 Working] [Throttle Stop]
High-quality, open-die style (free form) pneumatic forging hammer for the blacksmith. Striker air hammers are made to (O.E.M.) original equipment manufacture standards- and the level of quality of these hammers becomes strikingly (sorry about the pun:) visible when comparing this hammer side by side with its competitors. The Striker power hammer shown here is my own and since the first day it ran, it requires little maintenance and always runs trouble-free.
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Updates.Page Updates - May 23, 2009 - Drip Oiler section- re-write in progress continues. The oiler section re-write is 90% complete. New chapters have been added: Stowage Block and Shipping Bracket Removal.
The STC-88 is different from other hammers: The design and construction tips on this page were meant for the Striker STC-88 hammer. Striker Tool Company has greatly improved the overall design of the C41- style hammers, including a wider base, heavier anvil block, a heavier stronger frame, and much higher quality control during manufacturing than any other hammer in its class. The STC-88 is over 650 pounds (34%) heavier than other hammers in the same size class, and physical dimensions are very different from hammers made by other manufacturers. Owners of other hammer brands will need to modify the plans and designs described here, to fit their hammers.
Hammer setup is not for beginners. Air hammers are partially disassembled for shipping. The owner must be ready and able to build up the hammer and motor on a workstand, and install electrical service properly to the hammer. If the owner of a new hammer does not posses the skills of a master mechanic, and welder, and have basic knowledge of industrial electrical motors and starters, then their hammer will not operate correctly. Get help! This hammer runs trouble-free and with minimal maintenance if installed correctly! The STC-88 hammer is very heavy. At 2600 pounds (approx. 1200 kg), the owner will need access to appropriate forklift, loader, or crane to lift and move the hammer. The motor and pulley weighs 125 pounds and is difficult and dangerous for one person to move alone.
Designs presented here are my own. The hammer workstand shown here includes accommodation for lifting by 5,000 lbs. fork truck. The hammer mounting bolts are fully accessible from outside of the workstand. Thickness of the upper deck plate (hammer mounting surface) was increased to 1" to add more support under the hammer. And to create a heavier and more robust box frame, I used 3/4" flat steel for the sides. I installed my motor starter box on a swivel mount on top of the rear hammer cylinder where it was safely out of the forging area but still within easy reach of the hammer operator. A heavy duty 20 ft. (6 m.) electrical cable allows my hammer to be connected to any welding electrical outlet within the shop. Electrical power is connected to the hammer by way of a service panel that was bolted to the workstand.
Note that all photos in this treatise are of the author's air hammer. The hammer has been used for some very heavy work in a very dirty environment and consequently the paint has been scorched and chipped. All exposed parts of the hammer routinely become covered with a gritty mud made up of oil and dust and crushed iron scale. Frequent cleaning leads to more scouring of the paint job as the oil and grit are wiped away. This is a real hammer that is used for real work so visitors should not expect to see a new hammer with a beautiful new paint job. This is however, the place to see how well this hammer performs at maximum forging capacity in a dirty unheated shop.
Short
video clips of STC-88 hammer tapering very thin rods and forging
leaves. Tapering video demonstrates the excellent control this hammer has
despite being much too large for the work being done. The second video
shows leaves being forged in two steps, using hand held dies. The dies
were made on this hammer also.
Video data: Tapering video time 0:58, and file size 3.8 MB http://www.beautifuliron.com/Vid/VinePicketts2007tapersshort.wmv . Leaf forging video time is 1:51 seconds and file size 7.2 MB http://www.beautifuliron.com/Vid/VinePicketts2007leavesnarrativ.wmv .
Project
- Vine Wrapped Picketts. The videos linked here (on YouTube) show the
entire project with full narration. Visitors can see that air hammer work
makes up only a small part of the job. After the forging is done, there is
still assembly and cleaning. The air hammer is an asset that makes it
easier for the smith to forge special tooling, and much of the heavier
production forging. This video is 12 minutes long and was broken into two
parts.
Short video clips of this hammer operating, click on the movie pictures at right or click the links below. To save this video to your computer; right click choose "Save target as". Video shows the author's hammer during shouldering and drawing, cutting, and a maintenance test run.
Video data: http://www.beautifuliron.com/Vid/STC88_Shoulderanddraw.wmv Shouldering and drawing file size is 1.6 MB and time is 1:34. http://www.beautifuliron.com/Vid/STC88_Cutter.wmv Cutting video is .98 MB and time is 58 seconds.
More video clips of an STC-88 air hammer forging a 2" bar at the Soluquip website? Go here: *New Link January 21, 2007! http://www.soluquip.com/Striker_movies.htm
The purpose for the workstand is to raise the hammer to a more convenient height for forging. The STC-88 looks like a miniature Chambersburg forging hammer. All dimensions are literally scaled down in size and the working surface of the lower die is 21 inches above the floor - much too low for most blacksmiths to work with. With careful planning and design, the workstand will raise the height of the lower die to a more convenient and efficient working height while at the same time provide a stable, rugged, and safe mounting surface or platform for the hammer frame.
NOTE: when describing the "left" or "right" sides of a machine, I refer to the machine's right or left, not the user's right or left. In other words the right side of a machine is on the users left when the user is facing the front of the machine. Example; the hammer photo at top of this page shows the machine left side.
Unpacking
the shipping crate. The hammer is very heavy and must be moved with a
forklift. I pushed the hammer as far into the shop as possible while still
allowing space to build the workstand. A lot of equipment ships with the
hammer and everything must be unpacked, inventoried. The owner's manual
includes plans for a concrete workstand, and many of the items shipped
with the hammer are for use with a concrete workstand. As the project
begins, the shop is in total disarray.
NOTE: For safety, the hammer remained bolted to the shipping pallet until ready to place on newly built workstand.
Getting started - initial planning and project development. I chose to make my own steel workstand. Accurate dimensions were needed before layout and cutting could begin, so all items unpacked from the shipping crate were moved away from the hammer to allow the base of the machine to be measured. I made a set of crude drawings to help plan the work. Measurements were then taken to determine all "known" dimensions of the lower hammer die, thickness of the steel floor plate & upper deck plate, and thickness of the wooden cushion planks, and these measurements were added to the drawings.
What
height should the bottom anvil die be? This was the key dimension that
would be used to determine the total height of the finished workstand. I
decided to set the anvil die at 34-1/2" (87cm) above the floor. Here are
the known dimensions that I started with - the anvil die was 21-1/2"
(57cm) above the cast machine base, the floor plate was 1" (25.5mm)
thickness, the deck plate was 1" thickness, and the wooden pad between
hammer and deck plate was also 1" thick. Combining all of the measurements
listed above and then subtracting this total from the desired height of
the finished hammer and workstand (34
1/2" - 24 1/2") = 10". The sides of the box frame would need to be
10" tall.
Measuring
for length of the floor plate. The motor was placed behind the hammer
with belt pulleys aligned, and the total combined length from front of the
hammer base to the rear of the motor was measured. This last measurement
was needed to determine part of the overall length of the floor plate.
Every dimension was double checked and triple checked.
NOTE: that the floor plate will be 2 inches longer than the total combined length of the hammer and motor, and the floor plate extends past the rear of the motor to prevent the motor from colliding with walls or other objects when the hammer is moved.
Materials. Steel floor plate 1" x 31" x 60". Machine deck plate 1" x 21" x 38". Box sides and gussets 3/4" x 10" x ?. Wood cushioning boards 2 each - 5/4" Oak 12" x 38". Hammer mounting bolts 4 each - 1" x 7" plus washers and locknuts.
Deck
plate (hammer mounting surface) was cut first. The deck plate is 1/2"
longer and 1/2" wider, than the base of the hammer. The deck plate will
extend 1/4" past each side of the hammer base, and extend 3/8" past the
front of the hammer base. This lends support under the wooden pad that
will be placed between the hammer and workstand. No other parts were cut
until after all layout work was completed on the deck plate.
NOTE: the flywheel is fitted very close to the hammer, so the deck plate should be positioned flush with the hammer base or extend no more than 1/8" past the rear. Keep it tight in back.
Positions of bolt holes (at the base of the hammer) were transferred to the deck plate and double checked for accuracy. This was the time to catch mistakes before the work went any farther. On my hammer, I found one of the cast mounting bolt holes to be slightly out of square with the machine. This oddity was carefully transferred to the layout drawings on the deck plate. The deck plate was marked "this side up" to prevent mistakes, and 1-1/8" bolt holes were then drilled.
NOTE: bolt holes in a cast frame should never be considered perfectly spaced and should always be carefully measured to accurately determine the exact positions before cutting and drilling the workstand. Measure and measure again.
Layout drawing of box frame transferred to deck plate. The simplest way to begin making the workstand is to cut out the upper deck plate (hammer mounting surface) and then accurately transfer mounting bolt positions from the hammer frame to the deck plate. The deck plate was then drilled with 1-1/8" bolt holes and cleaned and de-burred. The deck plate could now be used as an aid to help plan the layout and dimensions and construction of the box frame.
Planning the box frame. I tried one of the mounting bolts each of the holes to be sure the there would be enough room to get a wrench inside the planned bolt hole wells. Drawings on the deck plate were adjusted as needed to make everything fit before beginning to cut the rest of the steel parts.
Welding the box frame. The box sides were cut from 3/4" x 10" flat steel and welded together. Concentrating on building the box first without the forklift channel irons. The forklift slots were made from 2" x 6" channel (inside dimensions are of coarse smaller than this so forklift forks of about 5" x 1-1/2" will fit in these slots). After the box frame was welded together I cut the fork channels to length and then cut out the slots in the corners of the box frame to accept the fork lift channels. These are not welded together until the next step.
Cutting
the remaining steel parts of the workstand. The 1" floor plate was
made 31" x 60" long. The floor plate would extend 1/2" in front of the box
frame, and to the rear the floor plate extended roughly 2 inches past the
rear of the motor. The length of the floor plate was determined when I
took my first measurements of the hammer (see the entry above titled "Measuring
for the length of the floor plate"). The long extension at the rear of
the hammer workstand would prevent the motor from striking walls and other
objects when the hammer is moved. All corners on the box frame, deck
plate, and floor plate, were chamfered or rounded off to remove sharp
corners.
NOTE: the spacing of front and rear hammer mounting bolt holes are not identical, and the size and position of the front and rear bolt wells are also different. Up to this point in the construction it wasn't necessary to keep the box facing one direction, BUT now it was important to orientate the box correctly.
Welding box frame to the floor plate. The front of the box was placed 1/2" behind the front edge of the floor plate and centered side to side on the floor plate. The forklift channels were placed inside the box frame with the open sides of the channel facing down against the floor plate. The frame was tack-welded to the floor plate, the fork channels were slipped into place and tack welded, and then everything was welded to the floor plate using full length beads and welded on both sides.
Reinforcing
gussets were needed to support the middle of the forklift channels and
prevent them breaking away from the floor plate if the force exerted by
the forklift becomes too great. To create the gusset shapes, a cardboard
pattern was made to fit closely around the fork lift channels. The gussets
extend 3-1/2" to both sides of each fork channel. The gussets were then
cut and welded in place.
The box was filled with sand and the deck plate was then placed on the box and a quick check was made to insure that the front and rear hammer mounting holes were in the correct position. The upper deck plate was then welded in place.
NOTE: in the photos (at right), the large hole in the deck plate is for filling the box frame with sand. The sand fill hole will be under the rear frame of the hammer - not under the anvil block!
The
wooden cushion between the hammer and workstand was made from 5/4" (30
mm) thickness oak boards. The oak boards were placed on top of the newly
welded deck plate and size dimensions and bolt hole positions were scribed
onto the boards. The boards were cut to size and drilled for hammer
mounting bolts.
The workstand was moved to its final position in the shop, the oak cushion boards set on top of the deck plate, and the hammer was lifted onto the workstand using the lifting eye provided for the rear cylinder. The hammer was aligned to proper position by levering it around with a tapered bar placed through the mounting bolt holes, and the hammer was bolted down. The hammer was now ready for build-up.
Motor
mounting plate. The large motor mount is made from several pieces of
3/4". To facilitate the tightening of drive belts the motor mount plate is
tipped sloped to one side of the machine as seen in the pictures. On my
hammer base I chose to move the plate to one side of the hammer so that it
extends about 2 inches past the side of the box frame. This proved to be a
mistake. I should have been centered the motor mount evenly between the
sides of the box frame. My side placement caused the motor to need more
lateral adjustment to the left to tighten the belts and consequently I
needed to trim the flywheel cover to allow the motor to move farther to
the side. I recommend following the distributor's design and centering the
sloped motor mount below the flywheel rather than offsetting it like I
did.
Motor
tensioner. The motor is connected to the flywheel with 5 v-belts. The
motor must be pushed against the drive belts with enough force to remove
all slack in the belts and prevent slippage. This called for a sliding
tensioner plate between the motor and motor mounting base, and threaded
rods and nuts to force the tensioner and motor against the belts.
MODIFICATION
- Treadle pivot bolts relocated to workstand. These are the
original treadle pivot bolts that were installed in the hammer frame by
the manufacturer. I welded the bolts to the workstand at a location that
is directly below the original pivot positions on the hammer frame. The
height of the treadle bolts (above floor level) is roughly the same as
original pivot holes on the hammer frame - approximately 3 inches (75 mm).
Adjustable treadle throttle link. The original throttle link must be lengthened after relocating the treadle pivot bolts. But what length would work best? And if I made changes later to the position of the treadle, the changes would again effect the length of the throttle link. An adjustable treadle throttle link allows flexibility in adjustment of the treadle to any desired height.
MODIFICATION - Making the adjustable throttle link. I cut the treadle throttle link at approximately 3-1/2 inches (93 mm) from the lower connection (near the treadle), and welded a 5/8" (approx.15 mm) threaded rod to the short section of throttle link. The long upper section of the throttle link was punched and drifted and bent 90 degrees to accept the 5/8" threaded rod. The threaded rod was then inserted through the drifted hole and reinstalled on the machine and, after establishing the desired length between the threaded rod and nuts, the link was adjusted for best effect.
Treadle
guard. The purpose of the treadle guard is to prevent the treadle from
being depressed if any part of the work should happen to fall off the
hammer during forging. This includes tooling and other objects that are
laying on the scale pan that might fall off the pan and strike the treadle
while the hammer is running.
The treadle guard seen here is made of 1/4" x 3-1/2" (6 mm x 93 mm) flat steel, welded all around the top of the workstand. The large gap between the treadle and guard allows me to place the large steel toes of my work boots between the guard and treadle from every possible angle. The treadle guard on my hammer is cut with a slight taper towards the rear end of the guard - matching the shape or outline of the treadle.
Overview
of motor of electrical installation. The electrical installation shown
here is very different from the vendor's working showroom demonstrator
hammer installation. I have three concerns about how electrical
installation should be performed on my equipment. #1.) The rear of my
hammer is near the large entrance doors at the front of my shop, the doors
are poorly sealed and allow snow and rain to fall on the rear of the
hammer. All motor electrical wire runs and panels therefore require
weatherproof outdoor style wiring. #2.) I want the power cable to enter
and terminate in a service disconnect box on the back of the hammer to
limit damage to the cable and disconnect box connections, in the event
that personnel or machinery trip over or snag the power cable and pull it
out of the disconnect box. #3.) I wanted the starter to be mounted on the
machine - not beside it. And I wanted simple conduit protected wire runs
from starter to the disconnect box and to the motor.
Electrical disconnect box at rear of workstand. The disconnect box is located on the rear of the floor plate next to the motor. The mounting bracket is a simple affair made of 1/4-inch x 2-inch (6 mm x 52 mm) angle iron with a 1/4-inch x 4-inch (6 mm x 100 mm) square plate welded perpendicularly across the bottom and another similar size plate welded at the top for mounting the disconnect box. The plates are of coarse drilled for bolting the disconnect box and bolting to the floor plate. A piece of 1-inch x 4-inch (26 mm x 100 mm) square plate was drilled and tapped for 1/2-inch (13 mm) bolts, and welded to the floor plate, next to the motor. In this way I could assemble the disconnect box with the mounting bracket and then quickly bolt everything down to the floor plate.
Swiveling
bracket on side of hammer supports starter box. The Striker™ hammer
was provided with a separate stand for mounting the motor starter but, I
chose to instead place the starter on the side of the hammer. A two-piece
forged bracket was bolted to the top of the rear cylinder using the
lifting eye and one of the cylinder head bolts. The top plate of the
bracket is offset approximately 1/4 inch (6 mm) to lay flat across both
the center and sides of the cylinder head. The two-piece bracket is
assembled with a single bolt to allow the starter mount to be swiveled
into desired position before tightening the bracket together. The starter
was bolted to the bracket. This setup places the starter box in a location
that I find to be most ideal for operating the hammer.
NOTE: this is a single-phase 220volt installation in my shop.
Overview
of wiring runs. The power cable enters the bottom of the disconnect
box. Click on the thumbnails of the disconnect box at right. There are
three wires in the cable, black and green are hot 220-volt wires. The
beige color wire is a neutral and I connected it to the common ground lugs
at the left side of the box. This neutral line is also grounded in the
main power service panel that enters the shop. The hammer electrical
circuit is grounded for safety.
Red and blue hot wires from bottom of disconnect breaker are routed through conduit to the 'L' terminals of the motor starter. Green and black wires from the 'T' series terminals (from bottom of motor starter/overload breaker) are routed back through disconnect box and through conduit to motor. White neutral wires are connected from the common ground lugs in the disconnect box, to the ground lug in the motor, and to the neutral lug inside of the motor start relay box.
NOTE: the neutral lug inside the motor starter box is a dead end. I included this wire for future modifications that would use the starter wiring.
The Kwikstarter magnetic motor starter shown on this page is used for single-phase and 3-phase applications and is manufactured by Sprecher-Schuh. Note that the starter shown here has been rigged for single-phase use. This is a complete self-contained motor start with overload protection pre-installed in a small box. Sprecher-Schuh website is here: http://www.ssusa.cc/ . Sprecher-Schuh has posted a library with documentation on all their products including wiring diagrams and technical drawings. Check this library if original documentation that came with the hammer, has been lost. For more about installation of the Kwikstarter see item #2 in the Troubleshooting section farther down on this page.
Magnetic motor starter - theory of operation. With the push of a button, the motor starter connects the motor to a power source through contactors and maintains that connection by the use of electro-magnetic attraction until electrical power is lost or until the starter senses a jam or over-current condition, at which time the electro-magnetic circuit is broken and the contacts separate. Motor start relays allow fast switching of high current circuits without excessive burning of switching contacts. Modern motor starters are often provided with built-in or add-on overload protection devices. The motor starter seen on this page is provided with an add-on overload breaker mounted below the start relay. The theory presented here describes only the operation of the starter seen on this page.
NOT DONE
Grease requirements, specifications. Use the best grease available. I recommend using the best molybdenum marine duty grease.
Bearing Lubrication - 3 Grease Zerk Locations. A lubrication reference placard is attached to the lower right side of hammer frame. The lubrication placard shows the locations and lubrication frequencies of bearings that require periodic lubrication (greasing).
Warning! Electrical power must be locked out before removing guards and opening access panels!
Guards and access panels must be removed to lubricate the STC-88 hammer. Some new hammer owners might be a little uncomfortable disassembling their machine and damaging the beautiful paint job. Removing guards and access panels is part of routine maintenance. Lubrication is a requirement! Two grease points are located inside the hammer frame and both access doors must be removed to gain entry for lubricating these internal grease zerks. A third grease point is located behind the flywheel, so the flywheel guard must be removed to access this grease point.
NOTE. Paint and seals will be damaged during typical maintenance activities. The silicone sealant is cheap to replace, and new paint can be applied over scratches.
Warning! Flywheel and crankshaft could move unexpectedly and cause serious injury!
Rear
crankshaft bearing grease port is located between the flywheel and
hammer frame. The flywheel guard must be removed to gain access to the
flywheel. The grease port can be seen through one of the lightening holes
in the flywheel. The port is sealed with a check ball/check valve. Use a
needle-tip attachment with the grease gun to force grease into this port.
The grease port is very small so it may be necessary to first clean the
back of the machine to find it. Wipe grease port clean after greasing.
Front
crankshaft bearing grease zerk is accessed by removing the left-side
access panel. The access panel is held in place with two bolts. The
silicone sealant sticks to the hammer frame, so it may be necessary to
carefully pry the access panel off. Rotate the flywheel so that the pitman
bearing (lower end of connecting-rod) is at its lowest position - see
photo. Using a grease gun with a flexible hose, reach inside the frame and
connect the grease gun tip to the zerk and apply grease. Clean excess
grease off crankshaft and clean up old grease from inside walls of hammer
frame. DO NOT reach around, or through, the connecting-rod and crankshaft
because the crankshaft could still move unexpectedly and cause serious
injury.
The
connecting-rod bearing grease zerk is accessed by removing the
right-side access panel. And like the access panel described in the
previous paragraph, the access panel is held in place with two bolts. The
silicone sealant sticks to the hammer frame, so it may be necessary to
carefully pry the access panel off. Rotate the flywheel so that the
connecting-rod pitman is at its lowest position - see photo. Connect
grease gun tip to connecting-rod grease zerk and apply grease. Clean
excess grease off connecting-rod and clean up old grease from inside walls
of hammer frame. DO NOT reach around, or through, the connecting-rod and
crankshaft because the crankshaft could still move unexpectedly and cause
serious injury.
Inspect inside of sump oil drain port while right side access panel is removed. Note the position of the drain hose fitting on the side of the hammer frame - the drain port is located directly below the right side access panel. Use a clean rag to wipe drain port clean. Wipe out oil sump with a clean rag and inspect rag for metal shavings or other indications of mechanical trouble.
Re-sealing and re-installing access panels. Panels are fastened with two bolts. These bolts are snugged down - NOT tightened down super tight! A soft seal will prevent leakage. If oil leaks through the access panel sealant then replace the sealant - DO NOT over-tighten cover bolts. Excessively tightened bolts could break the cover panel. Cover panels are sealed with silicone sealant. I prefer to reuse the seals if they are not too badly damaged after removal. If old sealant is too badly damaged to re-use, I remove the old sealant and thoroughly clean and degrease the panel seal area, and apply a thin coat of silicone sealant and re-install after the sealant skins.
MODIFICATION
- Grease zerks installed in treadle pivots. The treadle pivot bolts
were welded to the side of the workstand as part of my throttle linkage
modification described earlier in the Throttle Linkage & Treadle Guard
chapter. In my opinion, an un-lubricated pivot joint is a candidate for
excessive wear. I installed grease zerks in the pivot brackets so that I
could lubricate these joints. I drilled the grease zerk holes slightly
above the horizontal center of the pivot bolt holes, tapped the holes for
1/8" pipe thread, and installed 90 degree angle zerks. Pivot bracket
lubrication frequency. The pivot brackets are greased during the same
maintenance interval as the crankshaft bearings and connecting-rod pitman
bearing.
The drip oiler supplies oil to the hammer cylinders for the purpose of lubricating the compressor piston and upper connecting-rod, ram piston, and throttle air valves. The cylinders require a continuous (un-interrupted) supply of lubricating oil at all times while the machine is in operation.
Drip Oiler - Overview & Theory of Operation
Drip
oilers used on small hammers such as the Striker STC-88 forging hammer
(photo at right) consist of a reservoir with distribution and metering
manifold, priming pump, check valves/one-way valves, and hammer cylinder
oil supply tubes. Metering valves control the volume or rate of oil flow
during hammer operation and the valves are fully adjustable by hand. Drip
domes on top of the reservoir manifold allow the blacksmith to monitor oil
flow. An oil level sight glass (small window) on the front of the oiler
reservoir will show a bubble when the oil level is low. The entire oiler
system is externally mounted on the right side of the hammer.
Oil system priming required before hammer start. Priming should be done at the beginning of each day before starting the hammer and anytime that the hammer has been idle for more than a couple hours. It is normal for oil in the supply tubes to slowly drain back into the reservoir when the hammer is not operating. The priming pump is used to purge air from the oil lines and to force oil to flow through oil tubing to begin initial lubrication of the cylinders. Transparent plastic oiler tubes allow the blacksmith to observe the oil and/or air in the tubing. Owners of hammers with metal oil supply tubes cannot see the oil and/or air in the tubing and should assume that the tubing has completely drained of oil if the hammer has been idled for roughly 8 or more hours.
Drip
oiler system uses no external power. The drip oiler works by pressure
differential alone - external mechanical or electrical power is not used.
Atmospheric pressure (ambient air) supplies the force necessary to push
oil through the oiler system. The breather/fill plug allows ambient air to
flow freely into the reservoir tank and maintains atmospheric pressure on
the oil inside the reservoir at all times. When the hammer is at rest (not
running), atmospheric pressure is static (equal) in all parts of the oiler
system, and no oil movement occurs. When the hammer is operating, low
pressure is induced at the hammer cylinder oil ports while the piston/ram
is passing over them. Atmospheric air pressure in the reservoir forces oil
through the system towards the low-pressure zone that is momentarily
present at the cylinder oil ports. Alternatively, after the piston/ram has
moved past the oil ports, the ports are exposed to the high working
pressures inside the cylinders while the piston/ram is moving near each
end of its stroke. The oil input check valves block exposure to the high
working pressures in the cylinders while allowing oiler operation during
the momentary periods that the piston/ram is passing over the oil ports
and inducing low pressure in them.
Visible oil flow seen in the drip domes is steady or stable because, the elastic properties of the oil tubing, and the air in the drip domes, smoothes changes in system pressure that are induced by the high/low pressure cycles at the hammer cylinder oil ports.
Simple and easy to use. Drip oilers have few working parts and are very simple to use and maintain. Drip oilers systems can be primed and oil flow adjusted for routine hammer operation, in under 3 minutes.
Oil
viscosity. Oil viscosity has a direct impact on the performance and
operation of the atmospheric drip oiler. Sealing characteristics inside
the priming pump and check valves, is derived from the oil used in the
drip oiler system. Using an oil that is too high in viscosity will result
in sluggish oiler performance. Using an oil that is too low in viscosity
will result in lack of sealing in the priming pump and check valves, and
reversal of oil flow as the high pressure cylinder air forces its way past
the unsealed check valves and pushes oil back toward the reservoir. Oil
weight requirements may vary according to the size of the hammer. Always
follow the manufacturer's recommendations when selecting an oil for use in
the air hammer.
Oiler operation in unheated (winter) shops. Temperature effects oil viscosity. It may be necessary to use a winter weight oil in an unheated shop. As the hammer warms up, radiant heat from the hammer will also warm the reservoir. Oil flow in the drip domes should be monitored and adjusted as necessary to compensate for the decrease in viscosity as the oil warms up.
Drip Oiler - Operating Instructions
Check
oil level. Oil should be added when a bubble first begins to appear in
the top of the oil level sight glass. Note that the oil supply is drawn
through the priming pump, so the priming pump must be submerged in oil at
all times to prevent air from being ingested into the oil supply. If the
oil level falls below the middle of the sight glass, then the priming pump
is no longer submerged in oil. To re-establish normal oil flow after air
has been ingested into the priming pump, follow the directions in the
paragraph titled Re-establishing priming pump oil flow after low oil
level has occurred, further below in this chapter. If oil level is ok,
then proceed to next step.
Metering valves must be open for oiler operation. Open the metering valves if they are not already open at this time. Do not omit this step- valves must be open for oil to flow. The metering valve knobs are adjusted by hand, and they are also provided with screw driver slots in case they become stiff or difficult to turn by hand. Turning them clockwise restricts or shuts off oil flow. Turning the metering knobs counter-clockwise opens them and increases oil flow. The exact valve setting is not important at this time because the valves will be tuned to proper oil flow after hammer start. If the valves are already open due to recent hammer operation, then leave them alone.
HINT: Temperature & oil weight/viscosity will directly effect the volume of oil that flows at any given setting of the metering valves. The colder the oil, the slower the oil flows and the more the valves will need to be opened. The warmer the oil, the easier and faster it flows and the more restricted the valve settings must be.
Operating
the priming pump. Push the priming handle towards the hammer to make
sure that it is all the way back and then pull outward on the handle and
hold for 1 or 2 seconds. Repeat as many times as necessary to completely
purge all air out of the oil tubes. It is normal for oil to flood the drip
domes so that it is not possible to observe oil flowing out of the drip
tubes while priming. As long as the drip domes can be seen to become
flooded while pumping the handle, and a slight back pressure can be felt
each time the handle is actuated, it can be assumed that oil is flowing
properly within the system. If the oil fills the drip domes too slowly,
then open the metering valves a little more and continue priming. After
purging all air out of the oil supply tubes, continue priming to begin
initial lubrication of the hammer cylinders. If oil does not flow, check
that the metering valves are open and then repeat this step.
How many times must the priming handle be pushed and pulled to prime the system? The answer to this question depends on the method that is used to prime the oiler system. There are two different methods for priming the oiler system.
The first method assumes that the hammer has been in use very recently and the metering valves are already opened and set. Leave valve settings unchanged. Push and pull the priming handle approximately 15 to 20 times for hammers with plastic oil supply tubes. For hammers with copper oil tubes, push and pull the priming handle approximately 10 to 15 times. The first actuations of the priming handle purge air out of the oil tubes into the hammer cylinders, and the last five actuations of the priming handle force oil into the hammer cylinders for initial lubrication. During very cold weather the blacksmith must push and pull the priming handle another additional 5 times to compensate for the reduced flow of cold oil. There will be less oil flow when using this method compared with the second method described below because the metering valves are already set to restrict oil flow and there is more resistance to priming.
The second method is for valves that have not been set previously. Open the metering valves wide open (1 or 2 full turns counter-clockwise). Push and pull the priming handle 5 or 6 times. Oil will quickly flood into the drip domes and into the cylinder oil supply tubes. One or two additional push and pulls on the priming handle and a large amount of oil is forced into the cylinders for initial lubrication. This alternative method may appear faster and easier compared to the first method described above, but will take longer to set proper drip volume after start up. Push and pull the priming handle another one or two times during cold weather to compensate for reduced flow of cold oil.
WARNING: It is common for a self-contained hammer to strike a blow once during startup as the throttle is placed in the 'Lift' position. Before starting the air hammer, make sure that all guards and covers are properly installed, work area is cleared of objects that could interfere with hammer operation, and warn anyone nearby that the hammer is going to be started. Serious injury can result if objects are pressing against the throttle or come in contact with the moving parts of the air hammer, or if persons are touching parts of the hammer that will begin to move during hammer operation.
Start
and run hammer - monitor oil flow in drip domes. Start the hammer and
set throttle to 'Lift' position. Move around to a location near the hammer
that allows the blacksmith to step on the throttle treadle while
monitoring oil flow in the drip domes on top of the reservoir. Hold down
the throttle treadle in 'Strike' position to make the hammer ram begin
reciprocating up and down until the dies almost touch. Observe oil level
in the drip domes as the ram is cycling up and down. Continue operating
the hammer while monitoring the drip domes - making sure that oil begins
dripping or flowing from the drip tubes. After two minutes the oil flowing
through the drip tubes will stabilize to a predictable number of drops/per
minute. If the metering valves are wide open, oil will flow out of the
drip tubes as a small steady stream. Droplets of oil are easy to see. But
when the oil is flowing in a steady stream, the oil is attracted towards
the inner front surface of the lower drip tubes where the oil flow is less
visible. If no oil is seen dripping from the drip tubes, then look closely
inside the drip domes to see if indeed the oil is flowing as a steady
stream.
Adjusting
oil flow. After running the hammer for two minutes and observing that
the amount of oil dripping (flowing) from the drip tubes has stabilized,
it is now time to set the exact number of drops per minute in each drip
dome. Continue to hold the hammer throttle treadle in 'Strike' position
with the dies almost touching while the ram cycles up and down. Choose an
oil zone to adjust first and adjust the appropriate metering knob to
either slow or increase the frequency of oil droplets in the drip dome as
desired. If oil is flowing in a steady stream, restricting or reducing oil
flow by use of the metering valves will cause the oil stream to slow and
break into droplets. It may be necessary to rotate the metering valve
knobs as much as one or two full turns clockwise to break the stream of
oil into droplets- this being especially common when the metering valves
have been fully opened before startup. Turn the metering knob clockwise to
restrict oil flow, or counter-clockwise to increase oil flow. Continue
cycling the hammer ram and observe that the oil flow in the chosen drip
dome has stabilized to the desired number of drops per minute. Adjust
again if necessary. Now adjust the second metering valve using the same
method. The metering valve knobs have no jam nuts so they are simply
adjusted and then left alone. The hex head fitting beneath the valve is
part of the valve and seat installation and should not be turned or
tampered with. Follow the manufacturer's recommendations for the
appropriate amount of oil flow (drops per minute) suggested in the
literature shipped with each hammer. As an example, I set my STC-88 oiler
at 10 drops of oil per minute for the rear compressor cylinder and 8 drops
per minute for the front ram cylinder.
HINT: If oil flow has stabilized to a steady stream after hammer start, here is a simple trick for speeding up metering valve adjustment; rotate the metering valves all the way closed and immediately open the valves enough to allow oil to start quickly dripping from the drip tubes. Wait 15-20 seconds to allow the number of oil droplets to stabilize to a predictable number, and then fine-tune the number of droplets per minute as described above in the paragraph "Adjusting oil flow."
Periodic oil level check. Oil level should be checked after every couple hours of hammer operation. If a bubble appears in the site glass, then it is time to refill the reservoir.
Filling
the oil reservoir. A fill plug is located on top of the oiler
manifold. Remove the fill plug and insert a funnel in the fill port. A
fine wire mesh screen has been installed in the fill port to catch any
dirt or debris that may accidentally fall into the reservoir. The screen
is very small and fragile, be careful not to damage it with the funnel.
Add oil to the reservoir. Note that the screen is very fine and will cause
the tank to fill very slowly, so add oil slowly and be careful to seal the
spout of the funnel tightly in the fill port to prevent leaking or
spilling of oil. Clean the top of the reservoir. Re-install the fill plug
finger tight. Be sure that the breather hole in the fill plug is clean so
that it will allow natural aspiration of the reservoir.
Oil weight requirements. The oiler requires high oil viscosity to function properly (approximately 50 to 60 weight). Follow the manufacturer's recommendations as to oil weight requirements. Using low weight/low viscosity oil will cause poor oiler performance or malfunction. When filled with the correct weight of oil, the oiler works well.
How much oil is needed to fill the oiler reservoir? The quantities of oil quoted here are for the author's STC-88 air hammer. Total capacity of the oil reservoir when empty is approximately 27 (US) ounces. When a bubble appears at the top of the sight glass, approximately 20 (US) ounces of oil is needed to fill the reservoir. If the bubble appears in the middle of the sight glass, roughly 23 (US) ounces will be needed to fill the reservoir to full again. 28 ounces is equal to 1 (US) quart.
HINT: To avoid over-filling a funnel and spilling oil on the reservoir, fill a clean empty motor oil container with hammer oil, and use the index marks on the side of the container to measure the volume of oil poured into the funnel.
Re-establishing priming pump oil flow after low oil level has occurred. There are two methods for re-establishing oil flow and these methods are similar, but with small differences, to those methods described previously in the paragraph titled 'Operating the priming pump.'
Method #1 assumes that the blacksmith has recently stopped hammer operation to re-fill the reservoir with oil. The metering knobs are already open and set for proper oil flow. Refill the reservoir with oil and then push and pull the priming handle as many times as it takes until the drip domes fill with oil. Hold the priming handle fully inward and fully outward for one or two seconds each time that the handle is pushed and pulled. The check valves move slowly and require one or two seconds to close after the priming handle is actuated in each direction. The restricted condition of the metering knobs will slow the flow of oil, and as oil begins to refill the oiler system, a small resistance will be felt against the further pushing and pulling of the priming handle. Priming pump oil flow is re-established when oil begins to fill the drip domes.
Method #2 is best when metering valves were closed previously or when method #1 doesn't appear to work. Open the metering valves wide open (1 or 2 full turns counter-clockwise). Refill the reservoir with oil. Push and pull on the priming handle as many times as it takes until the drip domes fill with oil. Oil will quickly flood the drip domes and no resistance will be felt on the priming handle because the metering valves are wide open and cause no restriction to oil flow. Remember to hold the priming handle fully inward and fully outward for one or two seconds each time that the handle is pushed and pulled. The check valves move slowly and require one or two seconds to close after the priming handle is actuated in each direction. Priming pump oil flow is re-established when oil begins to fill the drip domes.
After priming pump oil flow has been re-established, continue priming the oiler system in preparation for hammer run as described earlier in the paragraph titled Operating the priming pump. If the methods described here for re-establishing oil flow fail to bring the oiler back into normal operation, check that the metering valves are open, proper weight of oil is being used, and that the oil reservoir has sufficient oil level to operate the priming pump (no bubble in oil level sight glass).
Drip Oiler - Description of Design and Function
The
priming pump. The body of the priming pump is cast as an integral part
of the reservoir tank- the priming pump is located at the bottom inside
the tank. Check valves (one-way valves) inside the priming pump direct oil
flow through the pump body. A plunger and return spring are installed
inside the pump. The plunger provides the necessary pumping action as the
priming handle is actuated. Pulling outward on the priming handle forces
oil through the system, and pushing inward on the handle refills/recharges
the priming pump. The return spring pushes the plunger and priming handle
back to the refilled/recharged position after the blacksmith releases the
priming handle. A collar (cover plate) and gasket are fitted around the
plunger to seal the top of the pump chamber. The gasket provides an oil
tight seal between only the collar and the top of the pump chamber. There
are no elastic seals around the plunger or inside the priming pump. Proper
sealing and lubrication of the plunger is dependent on oil viscosity and
close proximity of fit between the moving parts of the priming pump.
Priming pump characteristics and theory of operation. The priming pump induces oil flow by displacing oil from the pump bore into the flume capillary. Under construction. The collar fits closely around the plunger shaft to help seal oil inside the priming pump chamber but, the plunger piston fits very loosely inside the pump bore. This important characteristic will be explained here soon.
Rocker
shaft & yoke transfer motion of priming handle to pump plunger. The
priming pump handle is mounted to the end of a rocker shaft, the shaft
inserted through a plate and rubber gasket and through a bearing journal
in the top corner of the reservoir. The rubber gasket seals and prevents
the oil inside the reservoir from leaking out around the rocker shaft. A
yoke with a forked slot is mounted to the rocker shaft inside the
reservoir - above the priming pump. As the priming handle is pulled, the
yoke rotates downward - pushing the pump plunger down into the pump bore.
Pushing the priming handle rotates the yoke upward- lifting the plunger in
the pump bore. The plunger is connected to the yoke with a pin and tubular
bushing. The bushing acts as a roller and a spacer, reducing wear, and
allowing a smooth rolling/sliding action between the yoke and pump
plunger. The distance or length between the end of the yoke and the pump
plunger connection continually changes as the yoke alternately lifts and
lowers the plunger. The forked slot in the yoke allows a sliding
connection that absorbs changes in length between the yoke and pump
plunger- preventing binding that would otherwise result from a more rigid
or fixed connection.
Priming
pump oil passages. The vertical flume cast into the rear wall of the
reservoir tank contains a large oil capillary that conducts oil from the
priming pump to the distribution manifold. The flume capillary was drilled
vertically down through the inside rear corner of the priming pump where
the flume and pump merge together, and is visible as a large 5th hole in
the middle of the back wall of the disassembled oiler body. Two holes are
drilled horizontally through the side of the reservoir and priming pump
body - the first hole drilled all the way through the front of the pump
body into the reservoir tank- the second hole drilled through the rear of
the pump body and connecting with the oil capillary in the flume. A third
hole is drilled horizontally through the middle of the pump from the rear
- connecting both of the holes previously drilled through the pump from
the side. The pump chamber is bored vertically in the middle of the pump
body - the chamber terminating immediately at a depth that connects
(intersects) with the small hole that was drilled through the pump from
the rear. All exposed outer holes are plugged and sealed.
Priming pump internal check valves. Two check valves are installed inside the priming pump. The first check valve is installed between the reservoir oil passage, and the pump chamber inlet oil passage. The second check valve is installed between the pump chamber outlet oil passage, and the flume capillary. These two check valves direct oil flow through the priming pump while the pump is being actuated, but they do not otherwise effect oil flow during normal atmospheric oiler operation. The first check valve (between the reservoir oil passage and the priming pump) allows oil from the reservoir to fill/refill the priming pump, but blocks oil from flowing back into the reservoir while the pump is being actuated. The second check valve (between the priming pump and flume capillary) allows oil to flow into the flume capillary, but blocks oil from being drawn backward from the flume to the pump while the priming pump is refilling with oil. Oil flow direction through the check valves is identical during both normal atmospheric operation and priming pump actuations.
What
is a check valve? A check valve is a special hydraulic or pneumatic
device that allows (by mechanical action) fluid/gas to flow freely in one
direction but limits or blocks flow in the opposite direction. A ball and
spring are the most common form of check valve and this design is used in
the Striker STC-88 hammer oiler. In the example shown here (see diagram),
oil enters the inlet port and under very light pressure (atmospheric
pressure only), forces the ball off its seat and flows around the ball,
through the spring, and out through the outlet port. If oil were to stop
flowing, or try to reverse direction and flow backwards, the spring will
push the ball back against its seat and thus blocking or preventing any
reversal of oil flow. Check valves make this oiler work so take good care
of them.
There are two types or applications of check valves. The first is a completely self-contained unit that is installed or connected to tubing or plumbing in the hydraulic/pneumatic system. The hose fittings threaded into the drip oiler manifold and hammer cylinders are self-contained check valves. The second application of check valve is an internal or integral check valve this is installed inside of, or machined inside of, the hydraulic/pneumatic system housing. Internal/integral check valves can be seen or inspected only after opening or disassembling the hydraulic/pneumatic system housing. Two integral check valves are installed inside the priming pump housing on the STC-88 oiler.
Oil
seepage in check valves. The hard (inelastic) surfaces of the check
valve ball and seat, cannot be made to fit with absolute perfection. With
that said, it becomes apparent that there will always be a small amount of
seepage or leakage of oil through the check valve, and the volume, or rate
of oil leakage, will vary depending on viscosity and pressure of the oil
that seeks to flow in reverse direction through the check valve. This
leakage is very, very small and does not effect the oiler system during
normal operation as long as the proper weight of oil is used. With the
hammer at rest, oil will (over a period of hours) drain back down into the
reservoir. This is why a drip oiler must be primed before use after the
hammer has been idled for more than a couple of hours. Lower viscosity
(lighter weight) oil will seep in reverse direction through the check
valve more easily than higher viscosity (heavier weight) oil.
The oil manifold. The top cover of the reservoir contains an oil metering manifold to meter and distribute oil to each output tube or zone. The main oil gallery is drilled through the middle of the manifold from the rear. Oil enters the main oil gallery by way of a short capillary hole that connects with the flume capillary in the reservoir tank. Zone oil supply passages are drilled through the sides of the manifold - connecting the main oil gallery with the metering galleries. Metering galleries are drilled from the front of the manifold, through the zone oil supply passages, and finally terminating in a connection with the drip tubes underneath the drip domes. The working end of each metering valve consists of a needle and seat installed in the metering gallery between each zone oil supply and drip tube passage. Output oil passages are drilled through the sides of the manifold (underneath) the output check valves, each output passage ending underneath its corresponding drip dome (left drip dome- left output check valve fitting, and right drip dome- right output check valve fitting). Outlet ports are drilled down through the upper surface of the drip dome gallery- connecting each drip dome with the output passage below it. And finally, the output oil ports are drilled in the top of the manifold, connecting the ends of the output passages with the hammer cylinder oil tubes. The output ports are threaded to receive the output check valves. All open passages along the sides and rear edges of the manifold are plugged and sealed after machining is complete.
Metered
oil outputs. There are two metered oil output zones - left
zone/compressor cylinder and right zone/ram cylinder. Volume of oil flow
in each zone is controlled by adjusting the metering valves to increase or
restrict flow as desired.
Drip domes and visible oil flow. A pair of transparent (see-thru) drip domes on top of the reservoir/manifold allow the hammer operator to visually monitor oil flow and operation of the oiler. As long as the oiler system and tubing are in good working order (no leaks), oil flowing through the drip domes indicates the volume of oil flow feeding into the hammer cylinders.
External
check valves & oil tubes. External check valves direct oil flow in one
direction- towards the hammer cylinders. There are four external check
valves used on the STC-88 oiler - two output checks located on top of the
oiler, and two input checks threaded into the sides of the hammer
cylinders (one in each cylinder). Output check valve fittings on the rear
corners of the reservoir prevent oil from flowing backward into the
reservoir manifold. The output check valves allow oil to flow one way -
out through the hose side of the valve. Input check valves (one
threaded into the side of each hammer cylinder) prevent air in the hammer
cylinders from being forced into the oil tubes while the hammer is
running. Input check valves allow the oil to flow one way - into the
hammer cylinder.
Drip Oiler - Oil Flow Path Summary
Metering valves must be open to allow oil to flow. The oil flow path described here is always the same irregardless of whether the priming pump is being actuated or the oiler is in normal atmospheric operation.
Initial path of oil flow. Reservoir oil first enters the drip oiler system through a small inlet passage drilled through the priming pump housing inside the reservoir. The oil passes through a check valve and turns to flow through the pump inlet passage into the priming pump chamber. Oil from the pump chamber flows out through the pump outlet passage and turns to flow through a second check valve leading to the flume capillary in the back of the reservoir tank. The oil flows up and out of the top of the flume into the main oil gallery inside the reservoir cover/manifold.
Manifold
- Oil flow path. Oil from the reservoir flume capillary fills the main
oil gallery in the manifold, and then flows through each of the zone oil
supply passages to the metering galleries. After passing through the
metering valves, oil enters the drip tube supply passages and flows
through the drip tubes. At this point, oil can be seen dripping (or
flowing) from the drip tubes and filling the drip domes. Oil exits the
drip domes through the ports in the bottoms of the domes, then flows
through the output passages towards the output check valves. Oil exits the
manifold through the output check valves - flows through the oil supply
tubes to the hammer - and finally flows through the input check valves and
into the hammer cylinders. This is the end of the oil flow path for the
atmospheric drip oiler system.
Used oil is captured and recycled by the recovery method described in the next chapter - Used oil recovery.
Drip Oiler - Disassembly, Repair and Maintenance
Draining oil out of reservoir tank. A drain plug is installed in the bottom of the reservoir. Remove the drain plug to drain oil.
Disassembling the reservoir for maintenance - original factory installation. Reservoirs that were originally installed by the factory have no spacers between the reservoir body and hammer frame. It is necessary to remove the reservoir from the hammer frame because the core hole plugs in the rear of the reservoir are pressed tightly against the hammer frame during original installation - preventing disassembly while the reservoir is mounted on the hammer. Before removing the reservoir from the hammer, drain the reservoir tank by removing the drain plug in the bottom of the tank, and disconnect the oil hoses from the check valve fittings on the top of the manifold. When reinstalling the reservoir on the hammer frame, be sure that the reservoir is fully assembled before bolting back onto the hammer frame.
Disassembly of reservoir. There are four socket head screws holding the reservoir cover/manifold in place (one screw in each corner of the cover). After removing these screws, carefully pry the manifold off the tank-being careful to avoid tearing the gasket seal between the main body and manifold cover, and be careful to avoid damaging the fine wire-screen mesh that hangs down inside the reservoir tank. The plugs in the side edges of the manifold should not be removed for any reason. They plug the machined holes that were part of the manufacturing process and are sealed to prevent oil leaks and/or seepage.
Oil
level sight glass. The oil sight glass has a 42mm x 1.5mm threaded
barrel and rubber seal, and is threaded into the front of the reservoir
tank. A spanner wrench is used to remove and install the plastic sight
glass. I made my spanner wrench from a small piece of flat steel with 1/8"
(2.5mm) pins welded to the ends. New plastic sight glasses can be obtained
from Striker Tool Company. Expensive aluminum sight glasses with scratch
resistant glass can be obtained from J.W. Winco and from MSC Industrial.
http://www.jwwinco.com/ and
http://www1.mscdirect.com/
Drip Domes. Drip domes are threaded into the top of the manifold. If they become broken, the hole can be cleaned out and new drip domes threaded in place. Drip domes can be obtained from Striker Tool Company.
Check valves are NOT interchangeable. To determine which direction the oil flows through the valve, clean the valve, blow through it and note which direction the valve allows air to pass. Manifold check valves and hammer cylinder check valves are NOT interchangeable. Don't install them in the wrong component- they will block oil flow if mixed up.
Used
oil catch containers. The smaller air hammers (STC-55 & STC-88) are a
simple design such as might have been common around the early 1900's.
There is no pump that would have returned oil from the sump to the oiler.
Instead the oil simply drains out of the sump through a hole in the frame
below the compressor cylinder. On the author's air hammer, plastic oil
containers are used to catch oil that drains from the sump. The oil
containers shown here (photo at right) are typical 1-Quart (US measure) as
used for automobile motor oil. The recovery oil containers are oriented so
that the sight strip is facing forward and the oil level inside the
container is conveniently visible to the operator while standing in front
of the hammer. The drain tube from the hammer sump is fitted through a
hole in the cap of the recovery container. A fabricated bracket was welded
to the side of the workstand (below the sump drain) to support a pair of
these plastic oil catch containers. After one container is full, the tube
and cap are moved to the second container. Used oil can then be added back
to the drip oiler or discarded at a recycling center.
Under
construction.
Air
hammer rams are stowed in the raised position when the hammer is not
running. There are two types of exposure that will cause premature
wear of the ram. These are dust and humidity (condensation). Both dust and
water/condensation are attracted to the oily surface of the ram. Abrasive
dust will slowly grind away the surface of the ram. Humidity penetrates
beneath the oil coating and corrodes the surface of the ram. It may not be
possible to completely prevent these kinds of exposure, but hammer owners
can dramatically reduce abrasion and corrosion by stowing the ram in the
raised position.
A simple wooden block. The simplest method for stowing the ram is to place a large wooden block between the raised dies, and then stop the machine- allowing the ram to fall onto the wooden block. The block keeps the ram raised high up in the cylinder where there is little or no dust, and exposure to humidity and condensation is reduced. The block seen in the photo here is of oak and measures 8-1/2 inches (21.5 cm) tall, 3-1/2 inches (9 cm) x 6 inches (15 cm).
Initial inspection. Before operating the hammer I attempted to grease the crank shaft bearings and pitman bearing using the existing grease zerks. The zerks proved to be very poorly fitted and required replacing before grease could be applied to the bearings. For anybody reading this that isn't sure what I meant by poorly fitted zerks, it means that I expect to be able to force ALL grease into the bearing and not find grease flowing out around the sides of the zerk or all over the place. All grease needs to go to the bearing, and if a zerk does not allow for this then it must be replaced. It was necessary to replace the existing zerks with new ones. See the pictures at right.
Establish priming pump oil flow. I filled the oiler reservoir with oil and primed the oiler system as described in the Drip Oiler - Operating Instructions.
Lighter weight oil used for break-in. For break-in only, I used Sunoco ISO 46. I switched to a heavier weight after initially using about 1 gallon of lighter weight oil during break-in.
Hammer is shipped with preservative coating on machined surfaces. The preservative prevents rust from forming on the machined surfaces during shipment and storage. Oiler metering valves were opened wide for maximum oil flow during initial startup. Oil must be allowed to flow freely to dissolve and wash away the preservative coating on the machined parts inside the hammer. Some of the free oil will flow out of the front hammer cylinder onto the bottom die block and I kept rags nearby to wipe up the excess oil during break-in. Oil from the rear cylinder falls into the sump inside the hammer frame and drains out through a tube into a catch container.
Break-in involves operating the hammer with the ram reciprocating up and down almost a full stroke but not allowing the dies to strike. Drip oiler adjustment screws were opened wide so oil would flow freely during break-in operation. The large volume oil flow is for break-in purposes. A block was placed under the rear of the treadle and adjusted as needed to keep the hammer running by itself while I monitored hammer operation. It is wise to never allow a hammer to operate unless the operator is nearby. With the oiler running wide open, excess oil leaks out of both cylinders, and after the color of this leaking oil began to clear up, I adjusted the number of drips visible in the clear domes to about 20 to 25 drops per minute. Oil leakage continues to be dirty in color, so I let the hammer have lots of oil to clean itself during break in. Oil feed will be adjusted to about 8-12 drops per minute after hammer wear in.
Check
direction of flywheel rotation. Rotation must match the direction of
the arrow placard that is riveted to the top of the flywheel cover. See
the photo at right. The rotation direction must be corrected if it does
not match the arrow placard. For more about this task, see problem #3 in
the Troubleshooting section further down this page.
Trial run. First task with my new air hammer was to make a few simple tools. Beginning with a 1-1/2" x 1-3/4" bar I was able draw a 12" length x 1/2" thickness x 2-1/4" width in a single heat. This hammer replaced my old Little Giant 25lbs mechanical hammer and there is almost no comparison. The Little Giant would have taken more than a dozen heats to do the work that this hammer did in one single heat.
What
was the purpose of the shipping bracket? The shipping bracket was
installed by the manufacturer as a reliable way of securing the ram in the
raised position to protect the ram from corrosion during shipping. The
shipping brackets serve no other function.
It is not entirely necessary to remove the shipping brackets after the hammer has been placed into service. The studs and hardware securing the shipping bracket are installed as though the hammer will be used with the shipping brackets left permanently in place. There will be no harm in using the hammer with the shipping brackets installed, and as can be seen in some of the photos on this page, the author kept the shipping brackets on his hammer for almost a year before removing them. However, there is a large disadvantage to keeping the brackets installed. See the next paragraph for more on this.
Shipping
brackets will partially obstruct access for large forgings and tools.
The shipping brackets extend approximately 2 inches (50 mm) below the
collar of the sealing unit underneath the ram cylinder- thus partially
obstructing access to the upper end of the open die gap. The blacksmith
requires unobstructed access to the full height or gap between the hammer
dies while working with large forgings (such as wide steel bars worked on
edge) and tall tooling used on larger forgings. The shipping brackets must
be removed to work with large tools and wide bars worked on edge. At right
is a photo of the modified hammer with shipping brackets removed and studs
trimmed to length.
WARNING! Any mistakes made during this modification will result in changes in performance and damage to the hammer. Only a competent mechanic should make the modification described here. Get help! If you make a mistake, your machine will be damaged. This modification is not necessary and the hammer will perform well with shipping brackets left in place.
MODIFICATION
- Removing shipping brackets. There are two ways to perform this
task- on the hammer, and off the hammer. I chose to remove the studs and
finish the work off the hammer. Here is how work proceeded. The shipping
brackets were unbolted and removed. The studs were inspected to be sure
they were threaded fully into the cylinder. I measured the difference in
length of the short studs (the two studs that were not used for the
shipping brackets) and compared measurements with the length of the long
studs (the ones used with the shipping brackets). The long shipping
brackets studs were removed and trimmed with a hacksaw, sharp edges
dressed with a file, and threads were cleaned with a thread file. The
shortened studs were re-installed and tightened in the cylinder walls with
light torque. The original nuts and lock washers were then re-installed
and tightened with light torque. The completed job was then inspected to
insure that all studs were uniform in size. All studs and nuts were
tightened using light torque - NOT high torque - excessive torque could
damage threads in the cast iron hammer frame.
SafetyWEAR SAFETY GLASSES! The most important tool in the blacksmith's shop is safety glasses. Look closely at the photos at right. The scale can be seen flying up off the scale pan due to the shock and vibration during hammer operation. Everyone working with or near an air hammer should be required to wear safety glasses while the hammer is operating. During routine hammer operation this author has been sprayed with hot scale as a result of vibration, bending, welding, drawing, and also when oil and water was present on the hammer dies during forging. Other hazards include flying objects as hot iron was cut or tools broke under the air hammer. Despite this there have been no serious injuries. Safety glasses are a requirement in my shop. Make safety a part of your work too! Good safety habits reduce or prevent injuries.
Beware of position of the work piece and tooling at all times while using the hammer. The force of hammer blows can cause the iron or the tooling to jump forcefully and unexpectedly while the workman is holding them. The work piece and tooling can cause injury to the operator and others nearby if the operator fails to maintain proper positioning of tooling or work piece on the hammer. Tooling should be held in perfect vertical alignment. Any tooling held at less then perfect alignment risks that piece breaking or being sent flying across the shop. This rule also applies to the work piece that is being forged.
Oil
or water on die surfaces will cause a burst of high pressure steam or
gas resulting in scale being blown off the surface of the hot iron in all
directions. It is normal for oil to drip from the front ram cylinder of an
air hammer onto the bottom dies, and often after the hammer has been idled
prior to forging, the first blows will result in a visible burst of flame
and hot gases. Additionally any lubricants or coolants applied to dies
prior to forging hot iron will result in a burst of flame and hot gases
when forging begins again. It may be necessary to keep people away from
the hammer during operation, or at least make them aware of the hazard
described here.
Remove trip hazards and other entanglements from the work zone. The working area of an air hammer is necessarily open and unobstructed to allow free-style work methods. This open and unguarded condition also makes it possible for tools and other objects, or the operator's body, to come into contact with hammer dies accidentally. Keep the work area clear of any obstacle to the work.
Lock out energy sources before performing maintenance. Lock it out! This machine can cause serious injury if it starts unexpectedly while the workman is performing service or maintenance on the hammer. Electrical service to the hammer should always be locked out before attempting to change dies, attach tooling to the hammer, and when working on any part that moves or stores any form of energy during operation. For anyone that doesn't understand what this means, enter these key words in your search engine- "Lock out tag out procedures".
Glendale Forge, made in Britain. http://www.glendaleforge.co.uk/ Swages, cutters, and other forging tools for use in forging hammers. A small set of basic hand tools for use on open die forging hammers. If a smith is looking for ready-made tools for use in their air hammer, the tools offered at Glendale look very useful.
Centaur Forge http://www.centaurforge.com/ previously offered custom made hammer dies, spring swages, and a set of hand-held chasing punches made by Glendale Forge. These were available in their 2003 catalog. But the hammer tooling is not seen on their website. I don't know if they continue to offer these tools or if the tools simply don't appear on the Centaur website.
Making tools for the hammer, I currently use 4142 oil hardened molybdenum alloy steel. My larger tools such as hand-held hammer eye punches are roughly 2-1/2 inches to 3 inches tall. Handles can be made from 5/16 inch or 3/8 inch round steel. The handles are kept as thin as possible to absorb shock and concussion.
See the Forging Hammers Resources page http://www.beautifuliron.com/gs_forging_hammer_resources.htm for a small but growing collection of books and other resources for training and instruction for working with forging hammers.
The
crude drawings at right are the same drawings I used to set up my machine.
NOTE: The spacing of the hammer mounting bolt holes on the left side of my air hammer are different from the bolt spacing on the right side. This anomaly in bolt positions in large castings is very common and I strongly recommend everyone check hole spacing prior to marking and drilling the hammer mounting holes.
There are several problems that the new hammer owner is likely to encounter. I encountered some of these during setup of the hammer on this page. Fortunately I had experience wiring electrical motors for industrial applications. But if the new hammer owner isn't proficient in electrical work in the shop, these can be impossible to solve. Here are some common problems and solutions:
1.) PROBLEM: Motor starter relay operates (pulls in and seals) correctly when start button is pushed, but motor does not energize (no electrical power to motor). For 240v single phase only.
Relay may have been wired incorrectly by factory. This happened to me- one of the wires had been connected to the wrong terminal on the relay. The wiring diagram (near right) shows three configurations for 3 different voltages and phases. Note that the diagram does not show the fourth (spare) set of contacts that are available on the motor starter relay. I have modified the 240v single-phase diagram (second right) to show the NO contacts. The NO contacts are not part of motor run circuit. NO means 'Normally Open.' All of the contacts are in fact normally open, but only the 'L' series and 'T' series connections are part of the motor circuit. The NO contacts are spares available for other optional use.
If the black jumper wire was connected from the T2 line at the bottom of overload device, to the NO contacts (far right side connector) on top of the line relay. That is what I found when inspecting the wiring on my new hammer motor starter. The starter can't energize the motor if the single phase jumper is not connected with a line circuit through the relay and overload device. The hammer will not run if wired incorrectly.
SOLUTION: There are 4 sets of contacts on the starter relay (L1, L2, L3, & spare NO), and there are 3 circuits in the overload device(T1, T2, T3). The 240v single-phase diagram shows a jumper wire between T2 & L3. I had to move this jumper to connect from T2 on the bottom of the overload device to L3 at the top of the relay. At far right is a picture of the motor starter relay and overload breaker on my hammer, showing the correct wiring setup for 240v single phase. The NO contacts are the unused fourth set of connections at the right side of the starter relay. See the photo of completed starter circuit at far right. This is exactly how it should look when the circuit is correctly wired for single phase 220v without an emergency stop line.
2.) PROBLEM. The starter does weird things like rattle back and forth and will not stay connected on its own, tripping the circuit breaker in the overload device, and the motor won't come up to full speed and appears to lack the large amount of torque required to start and operate an air hammer. (for 240v single-phase systems only)
SOLUTION: Possible error might be that one of the two hot wires has been mixed up with the ground or neutral wire, creating a 120v circuit by accident. If the wall outlet is known to be correct, then wires could have been mixed up inside the plug, wires mixed up inside the service box on the hammer frame, wires mixed in the L1 and L2 and neutral connectors. Use a notepad to write down all wire colors used and compare with wiring in each box or plug. Are all wiring notes in agreement with the colors found in each box and plug? Make wiring connections to the proper terminals to match the diagram.
3.) PROBLEM. Motor turns in wrong direction.
There is only a 50%-50% chance of getting it right the first time when connecting the motor wiring. No harm done if it is backwards when first starting the hammer, but excess wear of compressor cylinder may occur if allowed to continue. Compare the rotation with the arrow placard riveted to the top of the flywheel guard.
SOLUTION: To change the direction of flywheel rotation, disconnect and lock out electrical power to the hammer, and change two wires inside the motor connections box on the side of the motor. Single phase: swap the #5 and #8 wires and re-connect. 3-phase: swap two of the three T-leads and reconnect. And any time that work has been performed on shop wiring involving 3-phase circuits, the hammer flywheel rotation must be checked each time, because any changes to the main 3-phase circuit can and will result in 3-phase circuit changes at the hammer and possible reversal of motor rotation at the hammer.
4.) PROBLEM. Motor makes a growling noise when energized but does not turn. Three phase only!
One leg of the three phase power circuit to the motor, is open. A growling noise and non-rotation of a three phase motor is the classic sign of 'single phasing'. Three phase motors need all three legs in the circuit to operate. Cut one leg and the motor sits still and growls.
SOLUTION: Check any fuses or circuit breakers that supply power to the hammer. Isolate the fuses to prevent feedback current from giving a false reading. More skilled electricians can check across two different fuses to find the defective one. If fuses and circuit breakers are all good, then check connections at motor and starter. Check each leg of the power circuit individually to be sure all three legs are 'hot'. Disconnect and lock out electrical power and fix any bad connections that are found. If a 'dead' phase leg is found on the supply side of the electrical service panel, contact an electrician or electric company for assistance.
Throttle
Lock (Obsolete)The page is here: http://www.beautifuliron.com/gs_stc-88_throttle_stop.htm .
New Striker hammers do not need this modification! All of the smaller hammers now have this operation built into the machine and the larger hammers have always had this operating function. Striker has upgraded throttles for older hammers. Some small hammers made by other manufacturers will continue to require the modification described on the throttle lock page..
Previously the smaller Chinese hammers arrived from the factory with only a simple throttle linkage and treadle lever. Anyone that has tried to operate one of these hammers knows how awkward the throttle can be when transitioning between the raise position and the strike position. Much of the movement of the treadle is needed to simply lift the ram and then rotate the valving into the striking position. But only a small amount of throttle is needed to rotate the valves past the raise position and into the strike position.
My throttle stop design is a simple bracket and sliding bolt that is adjusted to hold the throttle in the strike position with a small reciprocating motion of the ram. Again, this modification is not needed on the modern Striker hammers.
A Great Deal From Striker Tool Company
Striker Tool Company has a large lineup of air hammers in different sizes along with other tools and equipment, see their website at: http://www.strikertools.com At left are two pages from a recent sale flyer. If I were to guess which of his hammers are the most popular as far as number of sales per unit, I would guess that it is the 55 and 88 pound hammers.
Ready-made workstands are also available from Striker Tool Company. New hammer buyers will save a lot of time setting up their new hammers by purchasing the heavy pre-cast workstand offered by Striker Tool instead of trying to build a workstand like the one shown on this webpage.
Striker hammers have heavier frames and anvil blocks. The Striker hammer frame is larger, thicker, and heavier than its competitor. The anvil block is much heavier than most other power hammers - translating into much more powerful blows to the iron during forging. The striking force (hit energy) figures stated by most distributors are identical, but these figures do not account for the actual striking power of hammers with increased or decreased ram/anvil weight ratios. The hit energy figures are a mathematical representation that was arrived at by comparing the speed and distance of ram travel and weight of the ram. The hit energy figures are not a true representation of actual forging capacity of the hammers. A hammer of a given size will forge with more force against a heavier anvil compared with a hammer that has a lighter anvil. Pound for pound, the Striker hammers hit harder than other hammers.
Striker hammers have larger open die gap. The open die gap on the Striker (11 inches) is taller than the competitors' hammer (9-1/8 inches) and allows large tools to be used to forge heavy bars with more force than a hammer with a shorter open die gap. This was a very important feature to me because I forge large bars and use large (tall) hammer tooling, the larger open die gap gives me the room to do this work.
For blacksmiths, air hammers are the only real choice today. Whichever your preferences for hammer model or manufacturer, you really can't go wrong when buying an air hammer from a reputable dealer. Air hammers strike with approximately 2-1/2 to 3 times the force compared with a mechanical hammer of the same ram weight. The larger open die gap on an air hammer allows larger bars and special tooling to be used, tooling that could not otherwise be used on mechanical hammers with their smaller open die gap. While it is true that a Little Giant power hammer is great for drawing thin bars such as knife makers work, the air hammer is designed for everything else in which a large of amount of plastic manipulation of heavy bars is needed. And today the price of a working air hammer is the lowest I have ever seen. Now is the time to buy an air hammer- because they might not be so cheap in the future.
Latest update: May 23, 2009
Page created February 02, 2004
Write ups needed--- Motor starter theory, fix motor starter entry in troubleshooting section, die removal and installation
Photos needed--- Use of die removal tools, exploded view parts of steel workstand, all dimensioned drawings replace, lock-out devices.
