Fire Pistons

[Ogri the trog]

Aargh hang the expense,
Jeff I've just placed an order for a scout kit. I could have gone for a finished item but then I could have bought a lighter from the corner shop, I feel as though I need to work for the goal to better understand the processes going on.

This won't stop me continueing with my home made one though.

Ogri the trog

 

[Jeff Wagner]

Thank you Sir. I shall apologize now for the extended delivery time. I am making them as fast as possible, however we continue to have a significant backlog. Ah...but a lighter will not provide you with the same level of satisfaction nor a warm fire in the wind...

 

[match]

On the subject of fire piston advice from the experts, I've got a perspex fire piston I got cheaply some time ago - I've done all the tests with water etc, and the seal seems fine, but I can't really get it to spark.

I've used tinder fungus and charcloth in it - I can very occasionally get tinder fungus to ignite, but most of the time it fails. I've tried all sorts of approaches to hitting/pushing the piston, but with no real consistent effect. I almost always get a smell of smoke in the tube once I withdraw the piston, but no glow.

Can anyone offer me a (more) foolproof method to this?
Do I need to do anything to my tinder? i.e fray it/compress it/use more/less etc?

Feel free to say 'keep practicing!'

 

[Jeff Wagner]

Assuming one begins with a capable fire piston ( it is possible to have excellent compression but no heat generation ) and suitable tinder, there are two primary reasons for ignition failure. 1- inadequate speed and force on the down stroke and 2 - excessive delay on extraction. It is necessary to drive the piston into the compression zone toward the end of the piston travel. Then it is necessary to get the resulting coal out into the air where it can breath. Attempting to describe this process in words sounds more diffilcult than it actually is. If you've had an opportunity to view the video clips, you can see that it is nearly effortless. I am not familiar with the piston mentioned. Where was this obtained?

 

[Jeff Wagner]

Ah...The "perspex" term caused a bit of confusion. Now I see this is an English word for PMMA or acrylic. There are only two makers of clear plastic fire pistons to my knowledge. Does your's have two rubber o rings, black plastic piston and a rather small tinder cavity?

 

[match]

Ah...The "perspex" term caused a bit of confusion. Now I see this is an English word for PMMA or acrylic. There are only two makers of clear plastic fire pistons to my knowledge. Does your's have two rubber o rings, black plastic piston and a rather small tinder cavity?

Yep - that sounds right, although I'm not sure what you define as small - the cavity is (I'm guessing from memory here) about 5-6mm in diameter and probably about the same in depth.

I take it from the way you mentioned that one specifically that either you know this type to be usually successful (or knowing my luck) usually unsuccessful?

 

[Jeff Wagner]

I believe this type of piston likes to be lubicated with a light oil.

There is an extreme lighting method that sometimes works when others fail. I hesitate to recommend it however as there is an element of risk.of injury and it can be hard on the components. Place the end of the cylinder against an unyielding suface at about waist level such as a table top. With the piston inserted in the usual manner, ram the piston home using a stiff arm such that the upper body weight is applied to the stroke. Use care to avoid a slip as the end of the cylinder can pop out from underneath if the force is not applied straight down.

 

[Ogri the trog]

Ok we're on to mark two,
I replaced the bore liner with a new piece of similar tubing. The first was showing signs of damage from where the piston had kicked over sideways a few times when I was learning the art of the slap. I abraded the outer surface and epoxied into the body to eliminate the possibility of leakage between the two layers.
Next was the piston itself - but the first cut on the lathe was a bit too ambitious, it bent over to one side and was smashed into two bits. Another remake with a shallower O-ring groove, which means a much tighter fit of piston in the bore.
This tighter fit has made it very lubricant hungry - one stroke and thats it, so I'll look out for something a bit thicker. This might even lead my to using a different sealing medium, heading towards the all natural item that would be an ultimate goal.
Initial trials with the new and improved version were/are promising, several coals last night, but some of them took several attempts and some never made it at all.
Overall it has done what I had intended, taken a step towards improving the performance of the item and increased my understanding of what goes on. I'll continue to work on it and report any earth-shattering finds here.

Thanks eternal to Jeff for his input, especially to this thread I really appreciate your help - what a great guy!

Ogri the trog

 

[Ogri the trog]

On a roll now,
Just had my first, single strike ember.
No messing about, tear off some tinder, put it into the cup, locate piston in the cylinder, whack, there you go.

Pleased as punch.

Ogri the trog

 

[Jeff Wagner]

Attaboy... :d

 

[Galemys]

Jeff (or any other person who can help me out of my misery),

just out of interest, why is it that the tinder is placed in the cylinder rather than on top of the piston?
To me -blissfully unaware of any detailed fire piston knowledge- it would seem logical to somehow attach the tinder to the top of the piston which would make it easier to retrieve after the formation of a coal.

But as I said before, I am not quite an expert in this field (I once managed to render a bicycle pump completely useless in my attempt to make a fire piston ) so can one of you guys enlighten me?

 

[Ogri the trog]

Jeff (or any other person who can help me out of my misery),

just out of interest, why is it that the tinder is placed in the cylinder rather than on top of the piston?
To me -blissfully unaware of any detailed fire piston knowledge- it would seem logical to somehow attach the tinder to the top of the piston which would make it easier to retrieve after the formation of a coal. QUOTE]

Galemys,
I think you might have some lines crossed there buddy. The tinder is placed in a cup shaped hollow in the end of the piston, which is then inserted into the cylinder. It is this cup that allows the removal of the coal after the stroke, and some amount of handling thereafter. Some trials have been done using transverse drillings on the piston head which,I believe, were successful.

Are you going to join in and have a go at making one?

Mine is providing good service at the moment, thanks to Jeff's advice.

ATB

Ogri the trog

PS a bicycle pump would be way too big a diameter to make a fire piston, unless you were the Incredible Hulk. Better off sticking to a bore size, I guess, between 6 to 9 millimeters.

 

[Galemys]

Ogri,

thanks for your quick reply and for clearing up this foggy brain!

I am tempted to try and make one myself now but I dare say it will be at a slightly less professional level as you guys. I am currently scavenging the laboratory (I work in a blood bank laboratory, testing for allergies) for eh... MacGyver-style fire piston essentials (glass & perspex test tubes & rubber stoppers). I do think those test tubes need some kind of very heavy reinforcement though. But if they might work they will be easily replaceable.

Don't know how long it will take for version 1.0 to emerge, I have cut my thumb yesterday while doing some vaguely bushcrafty kind of thing which involved a Buck knife and a stick. Also I am feeling a bit tired due to antibiotic treatment for Lyme borreliosis (lovely beasties, ticks... )

I'm off to the gym now, training my arm muscles for the new bicycle pump...

Tom

 

[Jeff Wagner]

I was reading over the recent entries and a thought occurred - It happens some times...

Please do not confuse the traditional fire piston with those large glass laboratory replicas of the Hymen fire syringe. In the latter, the combustible is placed in the bottom of the cylinder as mentioned above. Other than utlizing the same principle of adiabatic compression, the two have little in common - especially in terms of performance. For example, a fire piston actually works and can be used to ignite the cooking fire. The other makes an interesting flash of light at ignition for the amusement and entertainment of physics students....

 

[Ogri the trog]

The other makes an interesting flash of light at ignition for the amusement and entertainment of physics students....

Ha ha ha just spat my coffee over the keyboard.

Nice one Jeff.

Ogri the trog

I suppose I'm going to have to learn how to post pictures now.

 

[shadow57]

Hello..

I spent a few months trying to make a fire piston from different materials. The only one that I got to work, was made out of brass.

Attached, is a simple drawing that should give you an idea.

The ideal lubricant was butter and parrafin 50/50.

Obviously you need a lathe and the fit needs to be free. The "O Ring" was sliced from a piece of rubber tubing that is used on fishing floats. Once you put the ring on , the compression can be felt. Its important that you get the correct combustion chamber size, or it will not work.

If your really good, you could add extra screw fitting on the end to keep spare rings or tinder.

Its amazing the look on peoples faces when I use this for lighting gas at work.

It takes about an hour to make one fire piston .

If anybody is really desperate ...I will gladly swop one for something...no cash please..

Hope this helps John

 

[Jeff Wagner]

Hmmmm...brass...very interesting.

My first few wooden ones were made without a lathe. It might be of interest to know it is quite possible to make a perfectly round shaft , accurate to within 0.002 inches, by hand and without power tools. I hope to make instructions available very soon.

 

[rich59]

Having access to plastic medical syringes I have several times tried to adapt one to light a piece of tinder. I would seal the outlet with a bit of bluetak. I usually end up snapping the plunger. I did once get a bit of paper to turn a little brown.

I have also played around a lot with bicycle pumps. I think the diameter is too big.

I occaisionally work on my own design of fire syringe (without gasket) where I just have a metal tube (currently a piece of towel rail) open at both ends. The bottom I close with a plastic bung that fits fairly snuggly. I once spent a couple of days playing with a "carrot and stick" experiment. In this experiment I pushed the tip of a carrot (that self trimmed by the tube cutting a solid cylinder of the carrot) into the top of the tube. I place it upright on a solid surface. I then pushed the carrot piece down the tube with a stick. As I let go the pressure at the bottom of the push phase the bottom bung jumps out releasing the contents . On this occasion out also came a cloud of steam - presumably from the carrot getting super heated - followed by the bit of carrot. Most repeats of this however merely got a bit of sludged carrot.

I think I am on the right lines and if I can figure out how to get a snuggly fitting top bung that slides down the cylinder without twisting then it might work.

I did try the more conventional idea of a gasket made of cordage (set into a slightly thinned down plunger to stop it slipping) but could not figure out how to deal with the bit that had double thickness of the cordage where it crosses over itself to lock it in position (as in a traditional sort of whipping). Any tips greatfully received.

 

[Ogri the trog]

Having access to plastic medical syringes I have several times tried to adapt one to light a piece of tinder. I would seal the outlet with a bit of bluetak. I usually end up snapping the plunger. I did once get a bit of paper to turn a little brown.

I have also played around a lot with bicycle pumps. I think the diameter is too big.

I occaisionally work on my own design of fire syringe (without gasket) where I just have a metal tube (currently a piece of towel rail) open at both ends. The bottom I close with a plastic bung that fits fairly snuggly......
I think I am on the right lines and if I can figure out how to get a snuggly fitting top bung that slides down the cylinder without twisting then it might work.

I did try the more conventional idea of a gasket made of cordage (set into a slightly thinned down plunger to stop it slipping) but could not figure out how to deal with the bit that had double thickness of the cordage where it crosses over itself to lock it in position (as in a traditional sort of whipping). Any tips greatfully received.

Hi Rich59,
Its good to know that there are others playing with similar ideas.
FWIW, I reckon that medical syringes would be a little too flimsy for a fire piston cylinder, possibly allowing a leakage at the critical point of maximum compression. Same with the "Blutack" bung, likely to give way too early in the cycle. Try using charcloth as a tinder, or some of the ones mentioned elsewhere in this thread - it really does make a difference. Paper is not easy to light by fire piston in my experience.
Bicycle pumps would be a bit ambitious I think, unless you have the strength of many men.
The towel rail cylinder might be on the right track but also strikes me as a bit too large a diameter. I have seen a video clip on the web of a working piston of about 1/2 inch diameter, but you're technique would have to be pretty good. I've stuck to the 7mm to 10mm range for my experiments, 8mm being the most successful so far.

As to your cordage overlap problem, I had thought of carving a small longitudinal groove so that the under layers of seal material restore the original contour - I haven't tried it myself yet, but it might work.

Good luck with it, and I really would like for you to prove me wrong where sizes are concerned.

ATB

Ogri the trog

 

[browndrake]

It has been some time since anybody has posted to this thread. I was wondering how people are progressing with there fire pistons.

I am new here. I found this site searching for info on fire pistons. I saw them last night while looking at some nice chipped knives online. I was fascinated by them and HAD to make one.... Went out to my garage and made a couple last night....didn't work of course. I hadn't read enough to know anything really that I needed to do, and I used wood that was too porous and let the air escape...

Today I am going to attempt it again, with better suited wood. From what I have read, I have my work cut out for me. I sure wish I had a lathe right about now...or knew Jeff's secret to making wood round without power tools..

No matter, I will have fun trying. If I am successful I will let you know.....Rather ...when I am successful...Not sure when that will be though.