DIY Fire piston

[Gailainne]

I tried Galemys design, see his thread here
But the copper tube although 15mm ID and the dowel 15mm ID, the slack between them was too much, for the o-ring to handle.

I remembered seeing aluminium tube and rod in B&Q so I popped in this morning to see if they still had it, and they did, a couple of quid per 1 meter length. I got the 8mm OD tube and the 6mm ID rod, and tested the fit in the store before I bought them.

The parts list

1 metre 8mm OD aluminium tube
1 metre 6mm ID aluminium rod
1 box of various sized o-rings, ( I got mine from Lidl or Aldi recently) Halfords and other places do boxes of various sizes tho.
1 tube of glue, whatever you have at hand, I had loctite superglue.
1 plumbers tube cutter
1 tub petroleum jelly
some char cloth.

I used a bench drill and a dremel then needle files to get the groove for the o-ring. And a standard drill to drill out a small pocket at the same end of the rod for the charcloth.

I tried brazing a small plug (4mm section of the rod) into one end of the tube, but it did'nt work, did'nt have the correct brazing rod I guess, so I glued it into place, seems to work fine.

Heres the finished bits an bobs




O-ring fitted and greased up, charcloth packed into the end, (I found that if its just loosely packed it has a tendency to stay in the tube.


Its not showing very well, but there is an ember there, I tried 3 times to get a photo, and got an ember each time, crap photos tho

Very out of focus photo but you can see the ember at the bottom.


Anyway, fun project, next one will be neater, and have some kind of handle.

Stephen

[Galemys]

That´s a neat fire piston Gailanne!

It looks heavy on the handpalms though, did you use a piece of cloth or something to protect your hands? Please post a picture when the next one is ready!

`But the copper tube although 15mm ID and the dowel 15mm ID, the slack between them was too much, for the o-ring to handle`

I use 12 mm tubing, 15 mm will need much more energy to compress the enclosed air.

Cheers,

Tom

[Gailainne]

Hmm interesting point about the 15 mm ID tube, I did'nt think of that, glad I switched to the 6mm rod, that was hard enough on my hands.

My method was to hold the tube in my right hand with my thumb over the capped end, then strike it firmly down on a hard surface, make a quick grab for the rod end and pull it out, hopefully with a glowing ember, which most of the time there was.

I think a bigger diameter would work better for holding, but not for compression, so I guess the easiest solution would be to encase the 8mm tube in something like 25mm dia or bigger wood, that way the whole thing can be held in the hand, should make for a quicker withdrawl as well, so more likely to have an ember.

Hmmmm

I think I'll have a play tomorrow.

Stephen