Step 4: Full Sized Tinder Hole

With the pilot hole drilled you can now proceed to drill the large hole. A number 31 bit seems to be about the right size. Notice how there is still a bit of material left between the hole and the piston end. If you don't leave a little room the drillbit could slip out!
<p>What is the actual inside diameter of the 1/8&quot; brass pipe? reason for the question is the i.d. of 1/8&quot; brass pipe varies lately, it used to be very close to 0.254&quot;, now it's likely closer to 0.270&quot; which really stretches the viability of an o-ring to seal the rod against the cylinder wall. It might be best to buy a brass tube of 0.500&quot; O.D. x 0.250&quot; , then reduce the end for threads - then cut threads for the cap. then with very fine sand paper reduce the rod by about 0.003&quot; clearance. thanks </p>
<p>I'm really not sure what to tell you, since the ID isn't the spec'd dimension you sort of have to take what you get or if possible just bring a micrometer with you. The whole idea was to use easily sourced off the shelf parts, I'm sure with the proper tools you could just machine all the parts yourself using rod stock but that was out of the scope of this instructable. Cutting threads etc seems a bit advanced, also the regular brass tubing I had access to was very thin walled (hobby tubing) so you couldn't thread any caps onto it, these were the best option I could find. To accommodate for the variability in the ID you could also try buying an o-ring variety pack and just finding one that works, that's what I did and then found the size that worked and used that on the rest that I built and they all worked fine, it could be that the box of brass pipe I got was all similarly spec'd. Sorry I don't have a better answer for you. </p>
FROM, LLuE88 <br><br><br> <br>Most vendors do not show nominal pipe i.d. , but a specific designer likely needs more info. Earlier there was a site that also spec'd the 1/8&quot; brass pipe nipple for a fire piston with no indication of required I.D., at that time I bought a 6&quot; brass nipple from Home Depot with the 0.254&quot; I.D. &quot;at one end only&quot; the other end was 0.275&quot;, change at about 2.5&quot; from end, talking about being upset at their quality control, they had no explanation for it {there were six more with exactly the same issue on the hangers}. I suppose ignorance is bliss, but a serious project person must research needed details or some how work around these sorts of problems. General use doesn't need i.d. or wall thickness<br>Below find link to one of quit a few that do give the required info. <br> <br>http://www.onlinemetals.com/<br> <br>With the i.d. knowledge you can easily make a plug from the same rod used for the piston itself by cutting about 1/4&quot; long, at the center of outside end put a deep center punch into it, then drive it into the pipe or tube of about 0.25 or 0.254&quot; i.d. about 1/64&quot; past flush from bottom end of cylinder for a solid closure. thanks<br>
what size is a 31 dill bit
A wire size #31 drill bit is 0.1200 inches in diameter, I used a 1/8 inch bit which is 0.1250 inches (the difference is about the thickness of an average human hair) to make mine entirely on a lathe (before I read this instructable).
@ Bryan Nice looking piston! Does the narrow end hurt your hand though when striking it? <br><br>@Shootin Wizard<br>http://en.wikipedia.org/wiki/Drill_bit_sizes
Thank you.<br>As for the narrow end it is 1/2 inch diameter and rounded on the end (rounding helps a lot) but if you try to learn how to make it work with tinder fungus as tinder in one night (many many many strokes one right after another for hours) it will make your hands VERY sore (I still have some small bruised spots after 2 weeks).<br>With this new optimized piston it is much easier to strike it though.<br>Also I have polished the cylinder very smooth, I think this will help with a lot of the problems people have with any fire piston and will likely make o-rings last longer.
You're probably 100% right about polishing the cylinder, how exactly did you go about doing that? Do you need special tools?
A gun cleaning kit and some metal polish come to mind but i haven't started mine to test it yet , going to the store tomorrow to find the stuff to make one.
<p>a small long drill bit or similar and some super fine sandpaper wrapped around it to run down the shaft would work good too</p>
Do you think it would still have enough compression if the piston were only four inches long, I couldn't find any longer at the store?
I love my fire piston, unfortunately I don't have a lathe so making the o-ring groove in metal was very difficult for me. I like the images in this instructable, what software did you use to make them?
Hey db85, I'm glad people are still using this instructable, congrats on making yours! I'd love to see some photos of your finished piston. I can imagine that the grove would have been hard without a lathe, do you mind if I ask how you did it? As for the images used in the instructable, I used Sketchup which is a free 3D modelling program formerly owned by Google and now by Trimble. I changed the style settings so the lines looked like watercolour etc then use exported as 2D images.
I followed your instructions. My piston is 4.0. Only thing I did that was different is that I didn't file the o-ring slot to an angle. I just cut a deep enough groove around the shaft as I was working with my dremel. Thanks for the instructable man!
Right on man, glad to hear it worked out for you. My only concern would be that if the edges of your groove are too sharp they may nick the o-ring when you're installing it and would significantly reduce the lifespan of the o-ring. Just running a file along the edges should be enough. You should post some pictures if you can, I'd like to see the results of what others have made!
So I am a little confused. The rod goes inside the pipe nipple right? Yet the materials list says1/4 rod and 1/8 pipe nipple? If the rod is bigger than the pipe that makes no sense. Unless you intend for us to turn the rod down until its smaller? Or am I just misunderstanding the directions?
That is just what they are called, I have no idea how or where they get the 1/8 part from. I know it sounds wrong but I assure you that wasn't a typo. No need to turn down the rod to fit or anything like that.
ur explanation is completly wrong, it does work like a diesel engine but diesel engines don't work like that. when air is compressed to a point where the partial pressure of oxygen is more than 1.6 it combines with most types of oils and explodes, thats allso why diesel engines make a lot more noise, because they compress the air a lot more than normal gasoline ones.
<br> &quot;it does work like a diesel engine but diesel engines don't work like that.&quot;<br> <br> That doesn't even make any sense.&nbsp; His explanation is correct, and although this is not <em>exactly</em> how diesel engines work, he is giving a comparison to those who do not know very much about this type of combustion.&nbsp; Also, the compression in a gasoline engine is not what causes the combustion as it does in a diesel engine.&nbsp; It uses a spark to ignite the fuel, not compression alone.<br>
a diesel engine doesn't use compression alone either, it requires a certain level of heat to have good combustion, which is why they have glow plugs to preheat the chamber. on a warm day you can start it without glow plugs, but near freezing temps you'll have no luck.
Well, a Diesel engine doesn't Use the heat, but it just Needs a minimum heat level to function properly... so it kinda does just use compression alone. As opposed to a gas engine which uses both the spark and the compression... In a Diesel engine, the Compression of the fuel-air mixture causes the molecules to heat to the fuel's Flash-point, the point at which it spontaneously ignites. The Fire Piston Works in the same way, where the combustible cotton is placed in the piston with the air and is heated to ignition by the compression of the air.
A fire piston works <em><strong>like</strong></em> a diesel engine. A fire piston is not a diesel engine.
Actually if you want to get REALLY technical a diesel engine works like a fire piston. According to some web sites including the Wikipedia on the fire piston Diesel got the idea for his engine from seeing how a fire piston worked.
diesel engines do not use sparks, they just use compression. thats why they are much simpler and less likely to have combustion problems. oxygen is cooler than you thought, no sparks, just pressure.
Looks like a good 'ible. <br><br>Just to add my two cents: I've found that wetting the char cloth with turpentine (not mineral spirits - real turpentine) then allowing them to air-dry gave me a much more flammable char cloth. I had the darndest time getting a fire started before this treatment, but now they reliably catch a spark and easily heat up enough to ignite tinder.<br><br>In the woods, I don't want to be relying on something that sometimes works. But every fire starting technique only works sometimes and that is why it is wise to have a variety of means to start a fire at hand. I already carry matches, tinder, flint, char cloth, cigarette lighter and a magnifying glass ... it wouldn't hurt to add a fire piston, too.<br><br>To those who question the wisdom of a fire piston, allow me to point out that they are very light weight, very simple to operate and work even when your fingers are too cold to deal with matches or a lighter.<br><br>That last part could be important.<br><br>Hint: load the char cloth in the fire starter before you need it. Then, if you have the rest of the fire starting materials gathered, you are only a slap or two of the piston away from a fire.
Is Brass necessary i have a steel rod of that exact diameter
&quot;minime&quot; is exactly correct, brass was chosen because it is way easier to work with than steel. I wouldn't even bother trying steel.
If you have a metalworking lathe the difference in working difficulty is negligible.<br>I made a test piston from stainless steel rod, it worked pretty good.
thats probably a lot harder to turn on a lathe...
WUNDERBAR!! &amp; congrats on getting featured. I'm curious as to what the shelf life of the char cloth is &amp; how should it be stored? Does it have to be cotton (an earlier post mentioned rope they had charred). I just moved to Maine to live with my brother &amp; we plan on doing some camping this year, however the state is very damp. Of course humidity will have an effect on the cloth &amp; the temp in which it will ignite, but if I can keep it dry the short time its out in the elements prior to being put in the piston shouldnt be a concern. Thank you for sharing &amp; your hard work.
I know that it would definitely have some impact but I'm not sure how much, if its purely moisture from water (as opposed to oil from your fingers) then I think it might just take one extra &quot;pump&quot;. I had seen some videos where a guy literally dunked the thing in water, dumped the water out, then had an ember within a few strokes. The heat generated for that brief moment in time is very high so it is quite plausible that it would dry it out, the second stroke would then ignite it.<br><br>I would definitely recommend storing the char cloth/string in an air tight container if at all possible anyway just to limit the exposure to moisture.<br><br>If you build one and use it out there please comment about your experience!<br><br>Good luck!
I followed your instructions to a T but when i push the piston down, air seems to be escaping past the O-ring. and sometimes the Oring get sort of stuck and rides up the piston. once in a while i will get it to go down and will get some compression as the piston pops back up a inch, but i am not producing a noticable amount of heat.<br><br>any suggestions? i have put alot of time into it this weekend and it is getting frustrating. thanks for the good instructable though!
Hi nikolaou, sorry you seem to be having problems. I'm not sure what to say, if followed precisely my instructions should work. You mention that sometimes the O-ring is getting stuck and slides up the piston, this should definitely not be happening and may shed some light on what is happening. <br><br>The first thing that comes to mind is whether your o-ring is too big in the first place?<br><br>Secondly, on your piston the angle of the piston where the oring sits may not be steep enough and is allowing your oring to slide up too far? (see attached image, sorry for the quality I only had mspaint to work with).<br><br>Another possibility is that you've somehow scored the inside wall of the tubing with the piston head and that is preventing a good seal.<br><br>This may be a stupid question but you are using vaseline or chapstick to lube the o-ring right? <br><br>You will need compression throughout the entire stroke or there will be no heat. If its sealed correctly you shouldn't even be able to get the piston down quite all the way (say 95% but not 100% of the way). <br><br>As for the frustration, I know, I've been there and I feel your pain lol. It took me more than just a weekend to get my first one going, probably spent 60hrs total. My hopes of this instructable were to help other people avoid that frustration ;)<br><br>Just think though how hard it must have been for the jungle tribes that made these with wood or bamboo and used string as the o-ring. Even with detailed instructions, better materials, and modern machinery these pistons are still tricky to make!<br><br>Good luck and if you figure out the issue please post back so other people can benefit.<br>
Projphphotography <br>Sorry to came in the conversation. <br>I ve built a piston, I guet in same diferente way.. in the rod I left a gap, Insted make like you said. But I press the road,...he road came back, pull back, the 0 ring its good,its seal, I have nice charcol(Because I ve try with flint stone,by stricking it) BUT I CAN NOT MAKE A FIRE...... <br>I HAVE TO SAY , IN SAME OPORTUNITY I VE SEE SMOKE IN THE PIPE,BUT NEVER FIRE IN THE CHARCOL. <br>do you have any idea.??? <br> <br>could I fill a bit the hole wich I ve made in the rod(piston) in same way? like expoxy, could help? <br>thanks for help.
your reply has inspired me to keep trying.<br><br>i am going to try with a new section of brass since i had to buy about 3 feet. <br><br>I am also going to try some different techniques when drilling and cutting the O-ring Groove. and when flaring the nipple.<br><br>also, i am using 3/16th inch O-rings, i also bought 1/4 and 5/16th but the smaller ones fit the best and there was no 1/8th inch at any of the stores i visited.<br><br>Will keep fiddling and get back to you, thanks for your help<br><br>p.s yes im using vaseline
I hope no one will use this for bad purpouses
It's easier to get a pack of matches... or a lighter.
the thing with those is that they have a shelf life and/or use life.
How far ahead were you planning on setting a fire for a bad purpose? They have WWII ration canteens with waterproof matches in them that still light on striking, so I guess if you're planning 50+ yrs in advance, then maybe these are better. My point was that a fire-piston creates a slow, smoldering ember really. Given enough time and effort, yes you could turn it into a big fire. If you were to use it for nefarious purposes... sitting there, blowing at this ember in your hands with some tinder nearby... would probably not be the best course of action. If I were burning something, I'd use the fastest means possible...
didnt read the bad purpose part till now, but waterproof matches will not work if they are damp. They will dry and be pretty usable. Fire pistons can make a fire out of more materials and quicker too.
Waterproof matches won't, but stormproof matches will :) <br> <br>http://www.youtube.com/watch?v=a8BY6AbHL9w
Great 'structable! I definatley plan on makeing one of these. As far as the matches comment,you could just take strike anywhere matches and coat them in melted paraffin. It keeps the heads dry and the paraffin is easiley removed for use of the matches.
the thing about matches is THEY ARE ONE TIME USE ONLY. ;)
Thanks I was going to say the same thing :)
That's a rediculas thing to say on an otherwise very good instructable. For someone to go to this entire process for 'bad purposes' is a joke... and I think a bit of an insult... Personally I think there are cheaper faster and more efficient ways to be a naughty person.
This was a wonderful Instructable and the first one I followed to make a Fire Piston. The plans were layed out very well which made it easy to follow. The only recommendation I would have for the procedure is to include the common size of the drill bit used. I did find one that looked close and it worked out well in the 3/16 area that you outlined.<br><br>One question for you. I believe i followed the instructions very well for both the char rope/paper and the piston. After testing with several materials and plunging my heart out I only got one piece of char rope to glow. The piston can be pushed in and then comes back out 3/4 of the way by itself. I was hoping that this was going to be easier than rubbing 2 sticks together. Any thoughts on what could be done differently?
It's a tricky thing to make really, it took me a few tries to get one that worked reliably. As for the problems you're having I can think of here are a few possibilities:<br><br>1) Even though you're getting a good seal your &quot;throw&quot; may not be long enough, if you followed the instructable though it should be ok. The reason I state this is if the throw isn't long enough you wont be building up enough pressure therefor not creating enough heat. Not having enough epoxy in the cap could also affect total pressure.<br><br>2) The char string/cloth isn't up to par, this as you say though probably isn't the case.<br><br>3) You've contaminated the char string/cloth. This is probably the most likely cause, oils from your fingers or from the vaseline used to lubricate the o-ring can render char string/cloth useless. <br><br>4) When in doubt add more lube to the o-ring ;) Not so much that it contaminates the char material mind you.<br><br>If you get it working reliably please post back with what you did to fix it. <br>Good luck!<br>
why dont you use something else and save the brass for a brass tap
Not sure exactly what you're getting at with saving it for a brass tap? By tap do you mean &quot;tap and die&quot; or faucet? Either way I'm not sure how either would apply here.&nbsp;<br /> <br /> If you meant using a different metal for the rod then the reason I used brass is that this is the material I found that works the best. Its easy to cut and shape and comes with a nice smooth finish. Steel is very hard to work with in order to get the o-ring groove and channel for containing the tinder. Aluminum is a little too soft and I found the stock to be too rough. <br /> <br /> I spent weeks working on this and even ordered a ready-made one just to see if I could learn from their design. This instructable shows the only method I found that actually yielded a repeatable result, after the first successful one I made 5 more exactly the same way and they all worked first try.<br /> <br /> Hope this helps.<br /> <br /> <br />
This is a great instructable and the time and attention you put into it shows.

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