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| Building a Fire Piston - by Craynerd |
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| madjackghengis:
Hi guys, I kind of got lost for a while, but in coming back, I'll say the wood version I tried didn't work, too much friction, not enough seal I think, and I didn't get on to a metal one. I think I will now, having seen this grow to two pages, and something from my Scouting days, we carried a tin of charred cotton or other fluff for flint and steel firestarting, and the fluff you find the wife's dryer screen, particularly after washing lots of cotton and not synthetics tends to ignite very readily. As a Scout, I've scorched cotton with a stick over an open fire, and I've used the fluff from a couple different plants that grow in wetlands, and have fine fluff inside, but those are seasonal. We used to take a stick and hack with a knife all over so it looked like a fuzzy pine cone sort of, to start fires, and thin splits of pine can be split down to almost hair, and lights very easily. I reckon it's time to make one that works, now that I've written about it. I'm thinking brass and stainess this time, cheers :beer: mad jack |
| daz:
It’s taken me a little longer than expected but I have finally got round to getting some photos and dimensions. After a little more experimentation I have now got a piston that is 100% reliable and is effortless to use. I am glad I have persevered with this as it has been frustrating me for a couple of years now. I know it is a really simple design, but trying to find a bore length/diameter that worked well and was easy to use has been a PITA. A couple of other simple mods have, I think, improved it a little. Anyway, pics and dimensions below THE FIRE PISTON PLUNGER PLUNGER GRIP Dimensions are as follows. I have not included the exterior dimensions of the piston tube as they are not relevant, all that matters is you incorporate whatever pattern or design you like into it. The plunger is 170mm in length and 12.7mm in diameter. The hole to hold the char cloth is 8.2mm in diameter and its centre is 5mm from the end. The slot is 4mm wide. I know 8.2mm is a strange size but I had just finished drilling for an M10 thread and was too lazy to change for an 8mm. The groove for the O ring starts 10mm from the end, is 1.8mm wide and 1mm deep. Thanks to Fergus Omore I was able to make the tool for the groove with little effort. The O ring is 13mm OD and 11mm ID, which obviously gives a thickness of 1mm. I also put some grooves on the end to make it easier to pull out of the tube. When finished with it you just reverse it and pop it back into the tube for storage. If you make the plunger 1mm shorter at the grip end the O ring will get enough grip to hold it all together when not in use. The tube has an ID of 12.9mm and is 170mm deep. I didn’t have any long reamers or drills and started off drilling one end, then the other. This worked ok but I was lucky enough to find some cut offs of aluminium air pipe with a thin wall, I later found some aluminium tube with a thick wall that was left over from a previous project, it was lovely and smooth inside and didn’t need any polishing. I turned down and press fitted an end cap to give a nice tight seal that won’t leak air or come apart, I also rounded of the edges to make it more comfortable to push down on. And finally....................... WE HAVE FIRE :clap: |
| Scuba1:
Now you done it. My other halves son has taken the 10mm fire piston as in the pics above with him to his engineering class at school. So they spent most of the afternoon including the teacher burning holes into their socks and other things and the teacher has decided to turn the making of those things into a class project and asked me if I could give him the measurements and a parts drawing etc that they can work to. Out came my more or less pointy pencil and the calipers again and I even found a not so dog eared bit of nearly white A4 paper and started drawing up a crap-o-cad. The short person of the house looked at me and said " don't you have solid works like we use at school ?" Errrr nope I don't and don't know how to use any CAD design program of any works, solid or otherwise. Now I can't say that to the short person can I ? Or he will loose the little respect he has. So I informed him that it would be just plain wrong to use any computer aid to make a historical device like this, that has been around for hundreds if not thousands of years and that a bit of paper and a pencil is as modern as I would want to go in this matter and by rights we should have scratched the drawing for this thing in a bit of slate. Damn it now I have to learn some sort of CAD thing before he finds out that I have no idea how to use them and that most of my designs are "filed" on the back of empty fag packets. Can you folks give me a nudge in the right direction of what to start off with, or I end up scratching the screen of this laptop with my dividers and stuff. To think that it all started off as a harmless bit of fun to get rid of some scrap bits I had under my bench. ATB Michael |
| DaveH:
Michael, Have a look here, there may be something to help. http://madmodder.net/index.php?topic=5011.msg56095#msg56095 :beer: DaveH |
| raynerd:
Michael Can`t help you much with the CAD other than to say I`ve tried a few and I`m found solidworks good to use once I`d got the basics. Some of the cheaper and free ones I couldn`t get my head around...that could very well just be me! I wanted to reply really to see how pleased I was that a teacher was getting interested and doing something fun that the kids will enjoy off the curriculum... I wish more would do this!!! Chris |
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