A Foot Pedal is an essential part of using the Air Hammers
Foot Pedals are fairly straightforward to make from Regulators
Introduction
Regulators are devices placed in between an air compresser and a tool such as a paint gun or rivet gun.
They control ("regulate") the air pressure on the output side of the regulator. The output pressure of regulator is pretty much constant. This is important since the air pressure coming into the regulator from the compressor tank varies as tank is drained and then replenished during use.
The pressure on a regulator can be thought of as being set with a threaded bar that depresses a spring which holds down a valve (see Figure 3 below). The tighter the spring is pressed against the valve, the higher the output pressure.
Since the speed & power of an air hammer is a function of pressure, we can control the air hammer using a regulator. However, having to stop and tighten/loosen the threaded bar is tedious in the extreme. We need to be able to adjust this pressure on the fly while using the tool.
To achieve this, we need to replace the threaded bar in the regulator with a pin that can easily and quickly be pressed in and out of the regulator. This is where the Foot Pedal comes in.
Note - Legal stuff Because We Are Americans. In this application we are using the Regulator in ways it was not designed to be used. The modifications shown here here may void any claims you have against the manufacturer of the Regulator; and by performing any modifications you agree to assume any and all risks involved.
Materials
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- Milton 1115 Regulator, 1/4 NPT
- 2x 1/4 NPT plugs
- 1 3" Nipple
- 1 90 degree elbow
- 1 threaded Male NPT connector
- 1 threaded Female NPT connector
- 7" x 15" piece of 3/4" Plywood
- 5 1/4" x 5 3/4" piece of Plywood
- 36" length of 2x4
- Drywall/Deck Screws
- Wood Glue
- Epoxy
- 3/8" x 4" bolt/10mm bolt
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Tools
- Flathead Screwdriver
- Drillpress
- 2" x 1/4-20 bolt.
- 3/8" Drillbit
- Lathe (optional, Drillpress will work)
- Cordless Drill + driver bit
- Wood Clamp
- Band Saw/Jig Saw/some safe way to cut wood
The Foot Pedals I use are based around the Milton 1115 Regulator (Figure 1). The reason I like to start with this is that it has a metal insert that can be easily removed and modified to take the Pin.
This regulator is pretty widely available.
It's obtainable from local Auto Parts stores to online through the Very Big Corporation of America.
The first stage of this process is to disassemble the regulator.
Unscrew the T-Handle all the way (Figure 2). Use a screwdriver to loosen the four machine screws (red arrow) that attach the Plastic Housing to the Metal Base
After removing the Plastic Housing (Figure 3), remove the machine screws from it. Store the Metal Base, Spring, Washer, and machine screws in a safe, dust-free place.
Mount a 2" x 1/4-20 bolt in the chuck of the drill press (Figure 4).
The drill press is NOT RUNNING during any of these steps - we're just using it to provide a very accurate vertical force.
Push the Threaded Metal Insert all the way into the Plastic Housing (Figure 5).
Eventually it will fall out (Figure 6).
Mount the Threaded Metal Insert into a lathe (Figure 7), and drill out the threads using a 3/8" drillbit (Figure 8). If you live in metric-land, a 10mm bit will work, and you'll need to use a 10mm bolt for the Pin later.
This operation can be done on a drillpress. Just be sure to keep everything clamped and aligned.
Push the drilled-out Metal Insert into the TOP of the Plastic Housing. In Figure 5 we pushed it out of the BOTTOM of the Plastic Housing. This is important so that the hex-flange on the Insert prevents the Insert from being pushing into the Housing when the Foot Pedal repeatedly depressed.
Now re-assemble the entire Regulator using the machine screws referred to in Figure 2.
Figure 10 lists the plumbing parts required to complete the airflow through the Regulator. The Regulator has In and Out marked on it; don't get them confused!
On early foot pedals I made, I put 2" Nipples on the crosswise outlets of the regulator. I figured I'd use those Nipples to help stabilize the whole assembly which is under quite considerable load when you stomp on the pedal.
However, when one of the regulators finally gave out, it was a nightmare to replace it since everything was locked in. On more recent versions I replaced the 2" Nipples and Caps with basic NPT Plugs to close those outlets (Figure 11).
My recommendation is that you do this too; however, when I took these photos for this post (well over a year ago) I'd not had to deal with this. Maybe one day I'll replace the pics with updated ones, but given its taken 18 months to get this far, I've just made annotations about this.
Figured 12 and 13 show how the plumbing is assembled. The orientation of the 90 degree elbow is not critical.
Again, I recommend replacing the 2" Nipples with NPT Plugs.
Don't forget to use teflon tape to make sure all joints are airtight.
From 3/4" Plywood, cut two rectangles as shown in Figure 14. The larger one (7" x 15") will be the Base of the Foot Pedal, and the smaller one is the Hold Down Plate.
Drill a hole in the center of the Hole Down Plate to fit exactly over the Plastic Housing of the regulator (Figure 15). There should be no play around the outside of the Housing, and the Hold Down Plate should rest on the machine screws that attach the Housing to the Metal Base of the Regulator.
Note the orientation of the Hold Down Plate relative to the Regulator - the 5 1/4" side is above the In and Out connections.
Cut two Support Blocks from 2x4's, as shown in Figure 16.
The Support Blocks are 2 1/2" tall, and 5 3/4" long.
Note that these are NOT just 2x4's cut to a 5 3/4" length - the height is trimmed down from 3 1/2" to 2 1/2". The height should match the height of the top of the machine screws attaching the Plastic Housing to Regulator Metal Base.
Cut two 6 1/2" long sections of 2x4 to make End Plates (Figure 17).
Securely attach the End Plates to the Base with screws and glue as shown in Figure 18. The screws should be countersunk into the Base as the screwheads will be on the underside of the Base and therefore on the floor.
If you opted to use the 2" Nipples to add stability, then drill a 1" hole about 1/2" deep into the End Plates, to accommodate the cap. See Figure 19.
If you're using the 2" Nipples, you'll need to drill two 1" diameter holes in the Support Blocks. These are centered 2 3/4" from the end and 1 3/16" from the bottom of the Block (Figures 20 and 21).
Figure 22 shows how the Support Blocks are placed in relation to the Regulator.
In this photo, the Blocks are not yet screwed to the Base; the photo simply shows that the Blocks will be very snugly position against the Regulator.
Glue & Screw a Support Block to the End Plates and Base (Figure 23). The screws will be driven in from the far side of the End Plates and the underside of the Base.
Place the Regulator on the Base, and position the Hold Down Plate over the Regulator. Push this assembly towards the End Plates (Figure 24) so that the Regulator is firmly against the Support Block glued in place in Figure 23. Position the front Support Block under the Hold Down Plate, and clamp everything in place (the clamp is absent from the photo).
Drill holes in the corners of the Hold Down Plate and screw it down. DO NOT USE GLUE on the Hold Down Plate as you'll want to remove it to service the Regulator at some point.
Drill holes to take screws from the underside of the Base into the front Support Block. Do not screw these pieces together yet.
Remove the Hold Down Plate and the front Support Block. Then re-mount the front Support Block with glue, and screw it down to the Base from the underside using the holes you just drilled.
Now re-attach the Hold Down Plate. Check that there is little to no movement of the Regulator in relation to the Base.
Turn the whole assembly so that it is laying on the End Plates. Mount a large metal Hinge on to the end plates using 1/4-20 bolts, as shown in Figure 25 and 26.
Cut the 3/8" bolt so that only the non-threaded part remains. This is now the Pin. Round off the cut so that it matches the shape of the T-screw removed in Figure 1.
Drop the Pin into the Metal Insert of the Regulator (Figure 26) and check that it is free to slide up and down without catching. From time to time this point will need to be lubricated.
Round the hex-head of the Pin as shown in Figure 27. I did this on my lathe, but it can be done on a drill press, or even "free hand" with a file or a grinder.
Notice the Epoxy around the top of the Pastic Housing/Metal Insert interface in Figure 27. Over time the lateral forces of the Pin will deform the Plastic Housing, and it will eventually need to be repaired and ultimately replaced. I've found the life span on these is in excess of 5 years. Usually the regulator as a whole need replacing anyway before this deformation becomes a serious issue.
The only real fix for this is to design a proper piston-style assembly to reduce the lateral strain on the Pin where it passes through the Metal Insert.
Lastly, mount a 12" - 18" section of 2x4 to the top of the Hinge using 1/4-20 bolts, as shown in Figure 28.