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Re: [Phys-l] fire pistons

John, et al!

This is the app. which "we" made at the make and take last year. Doug Johnson of CSUPomona (Cal Poly, Pomona) brought the parts for us to assemble. Much better than the PVC (I assume opaque), he instead supplied us w/ lucite cylinders. I think this was at the Trade Tech. College.

Not complete:

bc still hasn't searched for his, and is surprised by the history!

p.s. the first one I saw, some time ago, was a commercial one from an ed. supply house.

On 2010, Jan 19, , at 13:23, John Denker wrote:

This is a practical application of compressing a gas
quickly enough so that it is approximately thermally
isolated from the surroundings. Useful for making
fire without matches.

Evidently these things have been in use for thousands
of years:

Here are detailed instructions for making one out of
PVC and wood, without any special tools:
including a video of the thing in operation:

The jig for cutting the O-ring groove is cute, but
I would just chuck up the 7/16ths dowel in a 1/2"
drill, put the drill in a vise and call it a lathe.
A 1/2" drill is not that hard to come by.

I've never actually made one, but I think I would prefer
Schedule 80 CPVC since it has thicker walls and higher
pressure ratings than the more common Schedule 40 stuff.
Available from plumbing supply stores, not from Lowe's
or Home Depot.
or even
as opposed to

Another option might be to stick with Shedule 40 and
then somehow reinforce the last inch or two, which
is the only part that sees the highest pressures.

Also I would be tempted to scale the thing down from
nominal 1/2" barrel to nominal 3/8", just to make it
stronger, lighter, easier to carry, and easier to

Here are instructions for a smaller metal fire piston:

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