Quick and simple fire piston maybe?

[WhichDoctor]

Rite I've been looking at fire pistons recently, both on this site and on the web. I've seen the various attempts made by people on this site and what little i could find els-ware, and have seen how difficult they are and precise they are to make. Frankly I cant be bothered with all that drilling and sanding and tinkering, so I started idly wondering if there could be an easier way.

First I thought what about just taking a piece of elder and sanding down the inside, but all the elder I could find had a hole down the middle witch wasn't round.

Then I thought what if I got a piece of elder with a big hole then filled that with pine pitch and drilled a hole in that, but then I realized that drilling pine pitch would cores it to heat up and melt.

So I thought why not make a plunger as round and strait as possible fix this in place down the middle of a elder stem then fill up around that with pine pitch from the bottom, but then how would I get the plunger out? there mite be some sort of lubricant that would work but I don't know, will have to do some experiments. Also the heat generated by the action of the piston mite melt the pitch as well.

Then I had a sudden thought :thinkerg: , what if I got a round strait stick of some kind of wood that has a bark which can be slid off easily like willow, do the same as above filled up around it with pitch but then you could slide out the wood and leave the bark behind to leave a smooth strait hole and a plunger that fits perfectly. It would only work with green wood so you would have to put the plunger back in while it dried. With any luck the pitch would keep the bark intact and stop it splitting and the plunger would shrink inuf to allow you to put a gasket on it.

Is this a crazy off the wall notion that will never work , or am i an genius ? My bets on the pryer most of my ideas are , but you never know . Im going to give it a try and let you know how it go's, but do tell me if im being wildly over enthusiastic .

 

[dwardo]

Sounds like a great idea

I like the idea of the fire pistons but as you say a lot of work for something that can be achieved with a firesteel or flint. BUT if you can make one easily thats a different matter good luck !

 

[BOD]

Brilliant.

Even if it doesn't work at least the curiousity of early man is alive in his descendants :You_Rock_

 

[Galemys]

Hi Wichdoctor,

I like your idea but I don't know if it will work, I think the bark will be too fragile & too porous in use but you'll only find out by trying.
Maybe a lump of clay with a round metal plunger will work? if the plunger is put in perfectly straight it will make a perfect fit (well in theory…) so after baking you won't need a gasket (I am guessing clay won't shrink), just some lubrication. It 'll have to be a sturdy block of clay though. However I still think your idea is more elegant & less time consuming.
You're not the first however to try the casting method, some tribes in Borneo used to make fire pistons by pouring molten lead into a bamboo cast. The 'bore' was formed by putting a rotan stick in the middle:
Mr. Skertchley says that the metal of the cylinder is composed of two parts lead to one of tin. 'It is cast in a bamboo mould.... The mould is a thin piece of bamboo, split lengthwise, on the interior of which the ornamental bands, etc., are incised. A piece of flat wood, plank by preference, has a hole made in it the size of the bore. Through this hole a rotan is pushed, which also passes through a lump of clay tempered with sand stuck on the upper surface of the plank. The rotan projects beyond the clay to a distance somewhat greater than the length of the cylinder. The mould, bound together with split rotan, is placed centrally and vertically over the projecting rotan, thus forming a box closed below with clay, open at the top, and having a rotan in the centre. Into this the molten metal is poured. When cool the rotan is withdrawn, the mould open, and the cylinder is complete. A good mould will make three or four castings, but, as a rule, the first destroys it. The measurements of the cylinder are : - length, 3 1/4 inches; - width , 1/2 inch; bore, 3/8 inch. This is the average size; larger ones do not work well, smaller ones are of no use.'
This comes from an article on fire pistons by Henry Balfour (unfortunelately without the pictures):
http://www.firepiston.net/balfour/balfour.html

cheers,
Tom

 

[Ogri the trog]

WhichDoctor,
The idea is that the finished article can easily withstand the forces generated both by the action of compression and by the pressures created. The piston tends to be perfectly round and a precision fit in order to seal all the air, for its entire journey down the cylinder. I've tried making a few firepistons myself, and it strikes me that if it were really that simple then "Fire" would not be the mystery that it has become.
However, I do wish you well on your endeavours and am very interested to see how you get on.

Ogri the trog

 

[WhichDoctor]

Thanks for the words of support and advice, the chances are that it wont work but as I said you never know. It will take a while since I will need a hole lode of resin so will have to make a trip up to the local forestry commission pine plantation.

I will keep you all updated when I get round to it .

 

[rich59]

I still have some hopes on getting a plastic medical syringe to work. I have been close I think but not using the right tinder is one simple problem to get round.

 

[Ogri the trog]

I still have some hopes on getting a plastic medical syringe to work. I have been close I think but not using the right tinder is one simple problem to get round.

What sort of diameter are you using Rich? You may need to seal the needle end with epoxy and sleeve the whole thing into a piece of wood or horn - but the bore should be spot on. Might need to strengthen the piston rod too.
I'm supprised that you of all folk are having problems with tinder

ATB

Ogri the trog

 

[rich59]

I'm supprised that you of all folk are having problems with tinder

ATB

Ogri the trog

It was a while ago I last played with syringes. I was a tinder foot then.

I attempted to seal the syringe by pressing it into blue tack. This was 100% office craft! It may be time to try again.

 

[rich59]

I was thinking about elder tubes for fire piston. If you start out with a fairly thick walled, narrow and irregular bore elder tube, why not use a hand or bow drill to drill out a more even tube. You could close the bottom with a short replica of your piston rod. Then you have only to come up with a working piston rod (or two). I have tried to make a piston rod once. The principle of thinning down the part you wind the gasket onto needs patience and care. I didn't get the hang of how to make it a nice cylinder profile due to the method I used of a whipping that leaves a lumpy bit where the string runs underneath the turns. I guess you just carve a neat groove?

 

[WhichDoctor]

I was thinking about elder tubes for fire piston. If you start out with a fairly thick walled, narrow and irregular bore elder tube, why not use a hand or bow drill to drill out a more even tube. You could close the bottom with a short replica of your piston rod. Then you have only to come up with a working piston rod (or two).

I did think of that but since I have no experience with bow drills (haven't even managed to make fire with one yet ) I thought id give it a miss for now .

 

[Aragorn]

this is something i'v been playing with too, made a rought one out of stainless tubing, the bore may be too small though, about 6mm, also the plunger isn't a machined fit, although i have some promising first tries with it, get good force back when pushing the plunger in, but only when it's about half way into the tube, this may be a problem with the seals i'v chosen, but i think the main problem may be i need some better tinder, thought char cloth would be best but not had a go at making that yet , do you think cotton wool/vasaline mix would work as it does with flint & steel ?

 

[PatrickM]

This fire piston is made from elder, no modern drill was used, the selected piece had
an almost perfect bore, it was then polished inside with horsetail. The gasket was made
from nettle and lubricated with ear wax on its trial run ....works fine.

 

[WhichDoctor]

wow !!! That is amazing ! :You_Rock_ Was it really that easy? Mite have a go at that then. How exactly did you polish the inside with the horsetail? there is lodes growing round here. What are the dimensions of the piece you used?

And I also cant work out what the thing on the top right of the picture is.

It really is beautiful, grate stuff. :You_Rock_

 

[Culicoidis]

This fire piston is made from elder, no modern drill was used, the selected piece had
an almost perfect bore, it was then polished inside with horsetail. The gasket was made
from nettle and lubricated with ear wax on its trial run ....works fine.

I have to congratulate you on your craftsmanship once again. :notworthy

 

[Aragorn]

really puts mine to shame, anyone want to buy some stainless tubing

 

[spamel]

Is Patrick showing off again?!!

One question: How did you get the horse to stand still while you were polishing with its tail?



Good work again Patrick, Why not collate a huge amount of your photos and post them in one giant thread. It would be fantastic to see all of the kit you have made in one place!

 

[PatrickM]

Look for horsetail with a slightly wider diameter than the bore hole in the elder, pass a hazel wand into the cut horsetail tube and allow to dry out - it will shrink to fit. Clamp the elder between your feet and use the hazel with the horsetail sleeve like you were hand drilling for fire, this polishes the bore very nicely and it is not as brutal a sandpaper.

The item to the right of the photo is the tinder holder which slots into the top when not in use.

Is Patrick showing off again?!!

One question: How did you get the horse to stand still while you were polishing with its tail?

Can't help myself Spamel I'm a Kit Junkie.

That was easy - two constrictors front and back with a juicy carrot one inch out of licking distance.......Knotty eh

 

[WhichDoctor]

Look for horsetail with a slightly wider diameter than the bore hole in the elder, pass a hazel wand into the cut horsetail tube and allow to dry out - it will shrink to fit. Clamp the elder between your feet and use the hazel with the horsetail sleeve like you were hand drilling for fire, this polishes the bore very nicely and it is not as brutal a sandpaper.

Hmm I think the horsetail you've got must be a bit bigger than I've got round here. From memory the local stuff doesn't get much bigger than 3 or 4 millimeters thick . But I wonder if I could just get some of the smaller horsetail and split the stems and glue several to the stick, what size hazel stick did you use the same diameter as the existing hole or slightly bigger or smaller?

Thanks for the help :You_Rock_ .

 

[rich59]

Patrick,


What did you seal the natural bore with at the bottom end, and how do you arrange the gasket so the hidden string doesn't bulge out?