In this Instrucable I'll show you how to build a low cost Automotive Pedal Press. What is a Pedal Press? Well, it's a tool used to step on the brake or clutch pedal during service. It's especially useful if you're working by yourself and need to check the brake lights, for example. It's a common tool and they are available online and on the tool trucks for anywhere between $20-50 dollars depending on the brand and design you want. In the following steps I'll show you how to take a common $3 caulking gun and turn it into a pedal press. Okay, let's get started!
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Step 1: Disassemble the Caulking Gun
Tools and Supplies you'll need for this Instrucable:
-Drill bits, specifically 5/16, 21/64, "P", 11/32 or 23/64
-Angle grinder with cut-off wheel or hack saw
-Sandpaper and files for deburring/smoothing
-Handsaw or Jigsaw
-5/16 steel rod approximately 3ft long
-3/4" plywood chunk
-Four 1-1/4" screws
Step one is real simple, just take the caulking gun apart. To do this, undo the nut at the end and pull the rod out. Be careful not to loose any of the pieces, and of course, this device is under spring tension, so wear some safety goggles just in case one of the springs flies. Before you take it apart, do examine it and play with it for a minute so you know how it goes together. Take a few pictures if needed for reference. When it gets reassembled, it will be in the exact same way, so take notes now.
You'll notice I have two arrows in this picture. The red arrow points to the smaller tab. This smaller tab rides inside the handle and is what provides the forward action of the rod when you squeeze the handle. The hole in this smaller tab will be drilled out to 21/64. This hole is critical and must be this size, not smaller or larger.
The blue arrow points to the outer locking tab. This tab is the one you press your thumb with to release tension and retract the rod. The hole in the locking tab is drilled to size "P" and this provides the perfect locking tension while using the tool.
Also notice that there are two different springs. The heavy spring works with the small tab inside the handle. The lighter spring works with the longer locking tab.
Step 2: Drill Holes in the Tab and Handle
Use your driver/drill to enlarge the holes in the tabs and in the handle to accept the larger 5/16" rod. As mentioned, the smaller tab get drilled out to 21/64 and the longer locking tab gets drilled out to "P" size.
You also have to enlarge the holes in the handle itself. These holes get drilled out to 5/16", the exact size of the rod.
Step 3: Cut the Body of the Caulking Gun
Use an angle grinder with cut-off wheel or hacksaw here to cut away the body of the caulking gun. There's a nice and easy seam to follow for the cut. You're left with the handle, tabs, and springs which will be reused for the tool. Don't throw away those other pieces though! You'll use the original rod to help with the reassembly. I haven't thought of a good use for the discarded body, so let me know if you have any ideas. Soldering iron holder? Hanger? Hook? Well, we'll figure out something... let's get back to the pedal press!
Step 4: Find a Scrap Piece of Wood
Find a scrap piece of wood you can use for the stop. The stop is the piece that either levers against the steering wheel, or the seat. I made mine to be used against the seat because I feel it provides a better angle. But many of them are used against the steering wheel. If this is the case, you'd want a much smaller chunk of wood then I'm using here. The scrap I'm using is 10"x6". If you're making one to be used against the steering wheel you'd probably want half of that... 6"x3". The good news is, it's super easy to change out the wood in this design. You could also use metal for the stop, but I feel the wood is far easier to work with here.
So I'm using a 10"x6" piece of scrap 3/4" plywood. The 3/4" plywood is nice and strong and does well in this design. I cut the sharp corners away on the jig saw, but that's an optional step. I did sand it to get rid of any splinters and soften the edges. Then I found the center and eyeballed the handle portion over my center line. I then used the original rod and made a mark on the wood to locate where to drill the hole in the wood. Once that was done, I simply drilled a 11/32 hole through the wood. You can also drill a 23/64 hole through the wood, but I wouldn't go any larger than that though because the wood helps to support the rod too.
Step 5: Locate the Handle and Secure to the Wood Stop
Here I've taken the 5/16" rod and have come up through the backside of the wood. I then took four 1-1/4" screws and went through the holes on the back of the handle to secure caulking gun handle to the wood. I forgot to take a picture of the screws once done, but you get the idea. And yes, the 4 holes on the back of the caulking gun handle are already there! Super easy!
Step 6: Weld a Piece to the End of the Rod
Okay, I haven't talked much about the rod. But it's simply a 5/16" round rod. I had a scrap piece that was 40" long and I didn't cut it. But if I were looking to buy a piece, 36" long would do just fine.
Why not just use the same size rod, but just a longer piece? Well, because the rod size is between 1/4" and 5/16". If you place a 1/4" rod inside the gun as it sits, the rod is too small and it doesn't move forward when you squeeze the handle. Besides, the 5/16" rod is thicker and stronger, and you really need that extra strength the thicker rod provides to press on the pedals.
There are always sighs when I mention using a welder. I know many of you don't have one or don't have access to one. But fear not! You don't really need one for this project. You could simply find a chunk of wood, drill a hole half way through its depth and then glue it to the end of the rod. The purpose of the foot is that it has to be large enough not to slide off the pedal. As long as you can do that, you don't need no fancy pants welder. However, if you do have a welder, find a scrap piece of steel and weld it to the end of the rod.
Step 7: Time to Assemble!
Okay, so now the handle is screwed to the wood and the rod is ready. Time to assemble! Wait, I forgot to tell you what I did before I screwed the handle to the wood! To install the heavy spring and small tab is straightforward. This is a little tricky the first time, so take your time and watch for flying springs! In the first picture the red arrow points toward the pin inside the handle. It's important the small tab rides inside/against this pin as this is what actually levers the small tab and drives the rod. The trick to putting this together is to again use the original rod as a guide. Install the original rod part way through and add the small tab, making sure that the tab in riding against the pin on the handle, then simply slip the spring over the rod and then push the spring into place. Once in place, it will stay in place and you can then remove the rod. Alright, now screw the handle down to the wood!
Now assemble the rest of the tool. 5/16" rod through the wood and handle. Then push the rod through the heavy spring and small tab. Then the rod goes through the back side of handle, lastly add the light spring and slip the locking tab into place. And you're done! Easy, right?
Step 8: Enjoy Your $10 Automotive Pedal Press
Once assembled, this tool will provide you years of joy! Ah, okay... maybe it's not that exciting. But now you can press on your brake pedal while you're working alone. Start to finish this tool can be made in roughly 30 minutes and I'd estimate the cost at around $10. Pretty sweet for a tool that costs up to $50 from the name brand suppliers.
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