Philr - Fire Piston

[Philr]

Ive made myself a fire piston and tried charcloth in it, the piston seems a tightish fit as when i slam the plunger to the bottom it pops up about an 1" therfore i have compression but as yet no embers what am I doing wrong any tips?

 

[leon-b]

dont know lol but welcome to bcuk mate, you should introduce yourself in the intoductions forum
leon

 

[rich59]

That is a business like first posting. Welcome to BCUK. Great that you are in there and doing from the word go.


Did you test your charcloth before use?

I'm impressed you made your own piston. How did you make it?

 

[Galemys]

Ive made myself a fire piston and tried charcloth in it, the piston seems a tightish fit as when i slam the plunger to the bottom it pops up about an 1" therfore i have compression but as yet no embers what am I doing wrong any tips?

Welcome to BCUK Philr,

it sounds like you have good compression so my guess is that you have to practice your ´slapping´ technique. I´ve made myself a few fire pistons out of different types of metal tubes and rubber o-rings from the DIY-store (and last weekend I finally succeeded in making a working one with wound thread!). When I let other people try them out, most of them are not able to produce a coal. The trick is to quickly retrieve the piston rod after you slam it in, in one smooth movement. If the piston rod stays too long inside the enclosed tube the coal will be using up all the oxygen inside and die.

Hope this helps and good luck,

Tom

PS how did you make yours and what are it´s dimensions?

 

[Philr]

Mine is made from Water Buffalo horn with a brass push rod approx 6" long and a bore of about 3/8" with I guess about close to 1/2" gap at the base of the bore(including the chamfer from the drill end) yes I tried some char cloth using a swedish fire steel I carry Wow was I suprised at how it caught and dificult to put out once going.
Another thought guys Urinating on the once chared cloth then drying would this make it catch better ie using the natural saltpeter in the urine has anyone tried that as I have read that boiling Tinder fungus in urine helps it to ignite.
Ill see itf I can put some pics on to show you.

 

[Ogri the trog]

Hi and welcome Phil,
Firepistons are difficult to get right even when you know what you're doing so I'm impressed that you've tried one anyway. I made one a while ago which works occasionally but not predictably. 3/8 bore might be a bit ambitious, most that I've seen are in the 6 - 8mm region (though theres a video clip of one somewhere that looks to be 1/2inch ish). A 1/2" void in the bottom also sounds a bit big, you may want to think about trimming the top end to reduce this. You can test the compression by filling the cylinder with water and ensuring that there is no leakage past the gasket. Jeff Wagner (member on here and world reknowned MR. Firepiston) recommends a technique called "the crunch" as a method of getting an ember - though I can't get used to that method just yet.
Theres loads of information around both here and on the web in general.

ATB

Ogri the trog

 

[Galemys]

Hi Philr,

all of my working fire pistons have an inner diameter between 10 and 7 mm. The pistons themselves are between 12 and 8 cm long and the tinder cavity is just a few mm (3-5) mm deep. When making one, I try to place the o-ring or wound thread gasket as far on the end of the plunger as possible without disturbing the tinder cavity. In this way the compression is concentrated predominantly in the tinder cavity. It is also advisable to give the underside of the piston and the handgrip on the plunger or piston rod an ergonomical (rounded) design to prevent sore hands…
Charcloth works best as tinder in my opinion, tinder fungus (untreated Fomes fomentarius, just very fine strips) doesn't give repeatable results with my pistons.

Good luck with your efforts,

Tom

 

[Jeff Wagner]

Welcome Philr and glad to see your interest in the fire piston. 3/8" diameter bore is fine but a 1/2 gap at the bottom is not. Reduce the gap to zero and try again. When you have good compression you will not be able to make the piston bottom out completely. You will feel a cushion of air at the end of the stroke and there will be noticable bounce back of the piston. In use, you want to drive the piston into that compression zone which is where ignition occurs.

The crunch using decayed wood as tinder ...