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Building a Fire Piston

I was reading the “taig users” yahoo group recently where I came across a post in which someone had purchased a taig mill and lathe for the purpose of building a fire piston. Having the idea that this was some fancy engine, I quickly did a google search to find one. To my surprise this was not an engine but an instrument used to generate lit tinder for use out in the wild…and what an amazing method it used. It is simply a close ended cylinder with tight fitting piston with tinder at the end of the piston. When the piston is rammed quickly into the cylinder, the quick compression of the air generates enough heat to light the tinder!

Here is a quick video of it working with the pictures included:

A good googling on the topic found quick a few “make your own fire piston” instructions, but all using easy to come by materials. So using the measurements from these I set about making my own. The length is 4.25″ and the bore is 10mm (nothing like mixed measurements!). This was only a quick project, probably 3-4 hours machining but I struggled to get a good bore due to the fact I didn`t have a long enough reamer or boring bar. Still, a standard 10mm drill has worked with an o-ring to seal it well. This was all made up as I went along so there are a few mistakes and it hasn`t been polished!

The head of the piston was originally brass. You will see that although this fire piston works, making the bore 10mm is a little wide and so the force needed to compress the piston is quite high. A little too high for compressing it in your hands (I have actually done it but it hurt my palm!!) It is much easier to hold the cylinder and slam it down on something hard. I wanted to put a little cap on it anyway to hold some tinder, so I`ve made the cap out of steel. I guess it could be replaced as well. All this being said, if I was to make it again, I`d make the bore narrower so that less force is needed to be applied to compress the cylinder – so a steel cap would not be needed.

1/8″ hole in the bottom; this is where the tinder sits. The little square is the piece of char cotton I`ll be using as tinder.

The hole filled with char cotton.

Well, I should have cleaned it up a bit before taking this photo but this is the end cap. This provides a solid top, a pocket to store some char cloth and an extra washer to be used on the piston if needed. I`d make this bigger if I did it again.

The char cloth I made using a 100% cotton bed sheet, cut into four 3″ square sheets and put into a metal travel sweat tin. The tin had a small hole in the top (1mm) and was placed on a camping stove for 20 mins until all the smoke coming through the top had stopped, removed from the heat and sealed the hole. Lots of info on the net regarding char cloth. I was told that using char cloth is a “must” while testing a fire piston but I believe other tinders will work in it.

Char cloth lit and burning away…!

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4 responses to “Building a Fire Piston”

  1. John Hornick says:

    Nice job Chris!

    We use these, some made of hardwoods, in our Revolutionary War reenactment group; they work, sometimes better than flint & steel. I make my char out of linen scraps one and one half inches square. When the char or tinder glows, we pluck out the glow into a nest of flax tow or shredded cedar bark and blow until a flame is produced. The length of your fire piston is just right to fit into a standard tinder box by Ted Cash.

    Now, just put some rust brown on your steel cap and some patina on the brass part and come join our group in the woods!

    John

  2. Raynerd says:

    Hi John, thanks a lot for taking the time in posting a message. Interesting info about the Ted Cash tinder box, I`ll look into that because I`d quite like somewhere to store it. I think you would be suprised and shocked at how heavy the fire piston is. I think if it was to be used practically I would take a good bit of material off the cylinder and possibly even swap it for aluminium.

    It still staggers me how these have been going for so long and yet few people have seen them in action. I`ve never seen one on the internet before now, never seen one on TV (not even on any of the “outdoor survival” programs) and I`ve certainly never seen one in real life. I`ve shown it well over 20-30 people and no-one has said to me they have seen one either!

    Thanks again and all the best with your renenactments!
    Chris

  3. Paul Pitt says:

    Hi,
    I am a flute-maker but also a fire piston maker. We evidently share a common use of “Boyle’s Law”.
    Both Les Stroud and Bear Grills have demonstrated the fire-piston on their survival shows.
    Since I’m not a machinist my FP’s are made with abrass

  4. Raynerd says:

    Hi , many thanks for making a comment and I`m sorry for the delay in reply. I`ve been busy with a new role in my job lately and haven`t updated much on here! I haven`t seen Bear Grills use a FP – I didn`t know he had! Do you have any photos of your fire pistons? Your website is fantastic and I am blown away with your cave home! Thanks again for taking the time to post.
    All the best
    Chris Raynerd

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