Home Fire Pistons Tinder Videos Instructions How-To Primitive O-Rings Support Exotix
Drill (a drill press is nice but a hand drill will work)
Drill Bit (1/4" diameter)
Rat Tail File (round file that tapers to a point)
Aluminum Tube (8" long and 3/8" in diameter)
Wooden Dowel (8" long and 3/8" in diameter)
Rubber O-Ring (3/8" in diameter)
Sandpaper (180-320 grit)
1 Hour Epoxy Putty
The first thing you need to do is gather all the tools, materials, and supplies. I got everything at my local mega hardware store. When you are buying the materials, check to make sure the dowel rod barely fits into the cylinder or it is too large to fit. Just remember, you can always remove material to make it fit but you can't add material if it's too small. Once you have everything together, follow these steps.
Using the hacksaw, cut the tube to 8" in length.
Using the flat file, debur the outside edge of both ends of the tube.
Using the rat tail file, CAREFULLY debur the inside edge of both ends of the tube.
Using the rat tail file and sandpaper, CAREFULLY taper the inside edge of one end of the tube.
Using the hacksaw, cut the dowel rod to 8" in length.
Using the flat file, debur both ends of the dowel rod.
Insert the dowel rod into the drill and use the sandpaper to reduce it's diameter until it fits nicely into the cylinder. You don't want to force the piston into the cylinder and you don't want it to wobble around either. You want it so it will easily drop completely into the cylinder without stopping. Once it reaches that stage, stop saanding and move on to the next step and leave the dowel rod in the drill.
Clean up the end of the dowel rod and apply a very thin coating petroleum jelly to the flat part of the end. This will prevent the epoxy from sticking to the dowel rod.
Using the handle part of either one of the files, scratch up about 1/2" of the inner surface of the tube on the opposite end you tapered. This is so the epoxy will adhere nicely to the aluminum.
Using either file, scratch up about 1" of the outer surface of the tube on the same end.
Starting with the tapered end, slide the tube over the dowel rod until it rests on the drill jaws.
Cut the roll of epoxy in half, mix one half of the epoxy well, and plug the non-tapered end of the tube about an inch deep or until it starts packing against the dowel rod. Once it starts packing nicely, apply the rest of the epoxy to the end so you have a large mass to contain the compression.
Remove the dowel rod from the drill and use the dowl rod to 'tamp' the epoxy at the bottom of the cylinder to make sure it is sealing nicely.
Remove the dowel rod from the cylinder, clean up the end of the dowel rod, and put the dowel rod back into the drill. Set the cylinder aside and allow the epoxy to fully cure.
Using the corner of the flat file or the hack saw blade, get the dowel rod spinning and slowly cut a small line on the dowel rod a little more than 1/4" from the end.
Using the smallest point of the rat tail file, stay within your newly cut groove and expand the o-ring groove until you can easily slide the rat tail file a little deeper into the groove. When your groove starts to get a little larger, stop and check to see if the o-ring will fit into the groove. When the o-ring fits nicely, check to see if it will fit into the cylinder. If it doesn't, remove the o-ring and keep filing away until it will just barely fit into the cylinder. When it just barely fits, stop filing.
Using the sandpaper, starting with the 180 grit and progressing to the 320 grit, smooth out the o-ring groove even more. Don't sand too long with each grit as you will be removing too much material and taking a chance of making the o-ring groove diameter too small to work properly. You merely want to remove the file marks with the 180 grit and then remove the 180 grit marks with the 220 grit and so on. It only takes a couple seconds with each grit so be careful not to remove too much material.
After the epoxy has fully cured, test fit the piston into the cylinder using lube on the o-ring and make sure it slides nicely. You will have a little bit of resistance but it shouldn't be hard to push. If it's still a bit tight, repeat the sanding process and test fit it again. Repeat until you get the desired results.
Remove the o-ring and insert the dowel rod into the cylinder. There will be about an inch of dowel rod extend out of the cylinder and this is where you will apply the remaining epoxy for a handle.
Using either file, scratch up the exposed part of the dowel rod so the epoxy will adhere better.
Mix up the other half of the epoxy and apply it to the handle portion of the dowel rod that is sticking out of the cylinder. Be careful not to get any epoxy on or in the cylinder. Just get it close and that will be good enough. You may have to play with it a little bit to get your handle shaped the way you want it but just keep at it and when the epoxy starts to set up it will retain it's shape. Think of a round wooden cabinet handle for design inspiration. All you want is a large flat surface to reduce the abuse to your palm when operating the fire piston. Clean the end of piston shaft and set aside until fully cured.
Insert the 1/4" drill bit into the drill and slowly and carefully drill the tinder cavity a little less than 1/4" deep in the end of the dowel rod.
Using the sandpaper, debur the inside edge of the tinder cavity and lightly sand the entire end of the piston shaft to remove any remaining lube from the surface of the dowel rod.
Apply a few drops of super glue to the end of the dowel rod and spread it all over from the o-ring groove to the inside of the tinder cavity. Allow it to soak in for a few seconds and wipe clean with a paper towel. Repeat the process to make sure you have sealed all the pores in the end of the dowel rod. Allow to dry for a few minutes before testing the fire piston.
Clean the cylinder while the super glue dries. This will remove the lube from the bottom of the cylinder from when you applied the epoxy putty.
Your fire piston is now complete. Install the o-ring, put in some tinder, apply a bit of lube to the o-ring, and have a go at it. If all goes well, you will have a working fire piston. If it doesn't work, I'd start by re-sealing the end of the dowel rod. If it still doesn't work, you probably cut the o-ring groove too deep and you will need to make a new piston. However, it may be something as simple as poor quality tinder, not fast enough compression speed, not forceful enough when compressing the air, or maybe even your lube worked its way to the tinder cavity.
If your first fire piston don't work, don't give up as fire pistons require a bit of diligence and determination to manufacture. If you are successful, you will be ready to up the ante and make a better fire piston. Eventually you will be able to apply these techniques to just about any other material you wish to work with. I only chose these materials because they are easily obtained and easy to work with even if you have limited tools. In reality, I made my first fire piston using only a pocket knife. Good luck on making your own fire piston and if you need some help, just gimme a holler and I'll do what I can to help.
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