fire piston

S

sasha

Joined
Feb 28, 2006
Messages
2,435
I just found out that one of our customers has a fully functional machin shop with CNC. So i talked to him about making a fire piston out of metal and he said its not a problem. He can make is so close that if i put water in it and push down it would take lots of presure to get it out. He can go to less then 0.001in tolerance... Would it work to use only metal with no gasket?? If i would use metal is one type of metal better then another one for the fire piston??? I never had or used a fire piston so i realy dont know but cant pass up the chance to have some one make one for me. The guy said he likes to try and make diffrent things. He wants me to get him as much info about making a fire piston in case there is a better way to make it. If any one knows what is the best size for a fire piston i would love to know that.
My other Q is there any benifit in using a machine shop like he has to make a knife??? Get a flat stock and machine it untill it looke what i want my knife to look like and then harden and temper the steal??

Sasha
 
Some where in my junk notes I have a reprint of an article written in the 50's or 60's on fire pistons made of metal. I made one 20 years or so ago out of a 6" by 1/4" ID brass tube glued to a wood nob for the body. A 5 & 3/4" by 1/4" brass rod piston. The end of the rod was filed down slightly and wrapped with cotton string treated with Vaseline for a gasket, and the end of the rod was hollowed slightly to hold a piece of tinder. The whole thing was incredibly simple, it worked so I lost interest. Now the ones made all of wood I find interesting just because they are harder to make.
 
I would like to know how did you keep the tinder in place so when you pulled the rod out it came out too?? Did you have any trouble with hitting it hard enought to crush the tinder?? I been working on using some Orings for a seal. But i wanted to make so that out in the field you can use some type of rope and anything else that i could wrap for a seal. It would be great if you could find some of the spec's for the piston. Did you try and light anything else besides Char cloth??

Sasha
 
The end of the piston is drilled, maybe 3/16" deep and the tinder was just pushed in the hole. Didn't have to worry about it coming out, there was so much pressure that if you let go the piston would shoot out of the tube.
Your not really crushing tinder, your compressing air which causes heat and ignites the tinder. I used char cloth for tinder. As I stated it was a simple project that worked so easy that I lost interest.
A fire piston is a fun project but it still leaves you with an object that you have to carry and is some what sensitive to damp conditions and tinder selection. I already carry matches and a flint&steel. So I chose to concentrate my learning on fire making with materials that I find like, Bow & drill, Hand drill, fire saw, and fire plow. Still it is a fun toy.
 
Thanks Mike. I been thinking about making the piston from metal. I wonder if you could use it with some coal.. Just to have something extra in case you run out of Char cloth. What have you tried to use in the piston??

Sasha
 
I just recently made a fire piston on the lathe at my work. The bore is 7/16" x 3.75" deep. The piston is 3.6" long with no hole. I stick char cloth in the bottom and push once, then dump out the cloth, it has embers about 50% of the time. It is made of 6061 aluminum with a big plastic handle on the piston.

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Hi there Michaelmcgo. Thats looks alot of what i was thinking about. The only diffrence is i been thinking of making about 1/8 bigger in the inside bore. I figured that would raise the pressure. I did read somewhere a while ago about the best dimention but i can locate it again. What do you use to lubricate the Oring?? Have you tried anything else beside the Char cloth?? If you would have done it over again what would you change about it?? The reasons i ask so many Q's is that i want to learn from other people what they done right or what they done wrong.

Sasha
 
sasha said:
The only diffrence is i been thinking of making about 1/8 bigger in the inside bore. I figured that would raise the pressure. I did read somewhere a while ago about the best dimention but i can locate it again.
Click to expand...

I would think the larger the bore, the less the pressure.
 
Kl101 sorry we cant tell you how it works its a secret and you know what we would have to do after we tell you ^L*....




The idea behind the fire piston is that when you compress the air real fast the pressure would go up and same time the temp. The temp would get high enough that the Char cloth would ignite. There was an article that said the temp would reach over 1,000deg but it would be for a spilt sec only. Which should be enough.

Hi Esav the way i see it the larger the bore the more air it would hold. Then if you compress it to practicly nothing it would get more pressure. Well thats the way i see it but i might be wrong... Thats why im on here to learn from others. Im willing to listen and learn.

Sasha
 
You would be compressing more air but you would be compressing it over a broader area. So it's a wash. Also, the more air you compress, the more force it should take to do it.

If you want to raise the heat more, make the bottom of the tube conical, where the tinder goes. So the air will compress at the point you want it hottest by pushing it into a smaller space even than the bore.
 
Hi Esav i was thinking in the same lines as you mentioned. if i drill a small hole into the rode and make sure it gets very close to the bottom of the cly then the larger the bore the more pressure it would have. I also noticed that most of the pistons do have the hole even the one the natives are making so there must be a reason. As you said if you try to make too much preassure it might be a problem to compress the piston in the first place. Im still working on it and try to read as much as i can. The cool idea is that if the piston would get enough pressure and temp it might even ignite wood coal powder. So if it ignites the Coal it could be poured out and get a fired started. Yea im thinking big lol. keep those ideas comming lol at the end i might make the best piston or the biggest failur of a piston but then i would try again untill i would be happy.

Sasha
 
sasha said:
As you said if you try to make too much preassure it might be a problem to compress the piston in the first place.

Sasha
Click to expand...

There is a way to get A LOT more pressure, but I don't think it would work in a pocket-sized fire piston.

Make one a couple of feet long, small bore, foot brace at the bottom, and push the piston down by bending down and leaning into it very fast. :D
 
I made one with a bigger bore, but it was too hard to compress all the way. That o-ring is a normal rubber one out of a variety pack. I tried one with a hole in the piston, but couldn't get the thing to work right, I like just pouring out the char cloth. I've tried other materials (paper, Kleenex, match heads, etc.) but nothing seemed to work as well as char cloth (burnt t-shirt).
 
Hi Aarya thats the main site that started to look at before i though about making a fire piston. Its one of the best sites on the net. There was another site but i guess its not there anymote. It had alot of info in it.
Thanks
Sasha
 
aarya, thanks for the link and the inspiration. I just did an internet search and found a lot of information out there and places selling kits and finished fire pistons.

Fire Piston (sumpak) from Wikipedia
http://en.wikipedia.org/wiki/Fire_piston

Wilderness Solutions, Inc.
http://www.wildersol.com/
http://www.firepistons.com/

The Firepiston: Ancient Firemaking Machine
http://www.primitiveways.com/fire_piston.html
Steve Leung
http://www.firepiston.com/

Wildwood Survival – Fire Pistons
http://www.wildwoodsurvival.com/survival/fire/firepiston/index.html
http://www.wildwoodsurvival.com/survival/fire/firepiston/rbresearch/RBfirepistonresearch1.html

Granny’s Country Store - Fire Pistons
http://www.hollowtop.com/hopsstore_html/fire_pistons.htm

Midwest Native Skills – Fire piston
http://www.survivalschool.com/products/fire_starting/Fire_Pistons.htm

Primitive Fire
http://www.primitivefire.com/
 
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