start fire with air

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http://www.instructables.com/id/Start-a-fire-with-air/

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Start a fire with airby watermelon on January 24, 2008

Table of Contents

Start a fire with air .............................................................................................................

Intro: Start a fire with air .....................................................................................................

Step 1: So how does a firepiston work, anyway? ...................................................................................

Step 2: Materials and tools ...................................................................................................

Step 3: Polishing the cylinder ..................................................................................................

Step 4: Putting on the end cap .................................................................................................

Step 5: Cut the hollow and the seat .............................................................................................

Step 6: Test the fit of the piston and O-Ring .......................................................................................

Step 7: Add handles ........................................................................................................

Step 8: Insert char cloth and test ...............................................................................................

Related Instructables ........................................................................................................

Comments ................................................................................................................
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Author:watermelon

I'm an Emu. As a young chick my parents use to feed me watermelon and I loved it so much everyone nick named me, you guessed it, watermelon. Now thI have moved away from home I rarely get to eat any watermelon so whenever I think I hear the word "watermelon" my head naturally pops up and I responwith the question "Watermelon?" just as my persona image shows.

Intro: Start a fire with airTo do this we need to make a firepiston , which is a device for starting cook, camp and signal fires with air.

Firepistons seem so high tech that it's hard to believe they were notdeveloped at MIT or Carnegie Melon under a top secret DARPA contract with unlimited funding.Since the firepiston is also given credit for Rudolf Diesel's invention of his Diesel engine it is quite surprising that the firepiston was not invented by Diesel himself or b

one of his contemporaries or the likes of Ben Franklin and other European and American pyro based device inventors of the 16th, 17th and 18th centuries.

What historians note is that the firepiston was most likely invented in conjunction with the invention of the blow gun by prehistoric South East Asianssince firepistons normally found in the possession of those who use blowguns. The need to dislodge the internal partitions at each connecting joint inside a length of bamboo by ramma rod or piston through the membrane, and in the course of doing so, rapidly compressing the air thereby setting dust particles or the membrane alight, is the reasoninbehind co-invention.

I was so amazed at the technology and the science behind it that after building my own firepiston to prove to myself that the science and technology was real I could nresist sharing the science, technology and construction of my fi rst firepiston with you by creating this instructable.

Here then is a description of how to make your own working firepiston to see first hand for yourself that the science and technology do in fact work. I left lots of room fimprovement in materials, workmanship and degree of completeness for possible use in the field, if going beyond a demonstration is what you want to do.

Step 1:So how does a firepiston work, anyway?A firepiston can set an ember to burn as a result of energy being concentrated into a smaller and smaller space by compression of air resulting in a correspondingincrease in the air's temperature.

The principle of increasing temperature by method of compressing air is explained by the Adiabatic process in which the internal energy of a gas mustincrease when mass of air is rapidly compressed (or the volume of space containing a mass of air is rapidly decreased). The resulting increase in internal energy results in a r ise in thtemperature of air sufficient to light an ember, just like the pressure produced by an ice skater's blade is sufficient to increase the internal energy of the ice, which turnsice under the blade into water.

You can envision the effect in a 2D graph (below) with pressure as the ordinate (vertical) and volume as the abscissa (horizontal) and the adiabat or curve of constantentropy as the inverse relation curve. (Black lines are the curves of constant entropy.)

Rapid compression by a factor of 25 to 1 produces sufficient internal energy to send the air temperature to 800 degrees Fahrenheit. This temperature is sufficient toignite a piece of char cloth for use in kindling a fire.

After several tries and some fine tuning (better sealing with more lubricant) I was able to produce embers with char twine using the apparatus I constructed.
http://en.wikipedia.org/wiki/Adiabatic_processhttp://en.wikipedia.org/wiki/Fire_pistonhttp://member/watermelon/http://member/watermelon/


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Step 2:Materials and toolsIn general you want a material that will allow a cylinder to be bored smoothly with approximately an 1/4" ID which is around 6" deep and sealed on one end. IncidentaIf you do the math then you will see that it is the ratio of the height of the uncompressed space to the height of the compressed space that determines the height of thecylinder. In other words if you want .25" of char cloth to be ignited and you need a compression ration of 32 to 1 (instead of 25 to 1) to do it then the height of the cylindwill need to be 32 times .25 or 8", plus a little extra room to insert the piston.

The piston is a rod that fi ts snugly inside the bore of the cylinder using a gasket or seal of some type to make it air tight. The bore and the piston must be perfectlystraight and smooth to achieve and to maintain an air tight seal while it is being operated to produce an ember.

Natives might collect woods and cutting tools and keep at least one firepistons under construction in various stages of completion to be able to go f rom start to finishwithin minutes, hours or days.

To speed up some of the process required for construction requires use of a 1/4" by 6" brass nipple with an end cap filled with JB Weld and an aluminum or oakdowel to construct two test pistons. The pistons require a 1/4" OD O-Ring (or slightly larger diameter that can be filed down to fit) to act as an air tight seal. Nativeswould use fibers of some sort and perhaps anything from animal fat to earwax as a sealing lubricant. We can use lip balm or Petroleum Jelly.

I used a 1/4" power drill and a piece of dowel wrapped with an inch long sheet of tissue paper soaked with a solution of water and Bar Keeper's Friend (Oxalateacid) to polish the inside of the brass nipple to a mirror finish. (On the larger 3/8" nipple I'm working with now the inside of the nipple is much less smooth and straight

requiring various grades of sandpaper to hone it smooth before polishing.)

I used a hack saw blade , a glass file and the threads on a bicycle wheel spoke to fashion the seat for the O-ring in both the aluminum and in the oak dowel. A 1mbit was used to drill the hole in the char twine box. (Commercial units have a much deeper cylindrical hollow to hold more char cloth better.)

Originally I used a temporary piston stop made by using a pair of vice grips clamped around the piston shaft where the handle would be attached to the piston shaft tokeep the char twine from striking the bottom of the bore. This worked but it appears that commercial makers of firepistons hollow out the end of the piston much deepeprovide greater room for more char cloth and allow the end of the piston around the hollow to serve as the piston stop, rather than using a shaft pin or the handle as thpiston stop. BTW - commercial versions can run upwards of $50, but some come with all of the amenities such as char cloth and lubricant.

Image Notes

Image Notes1. End capped and sealed with JB Weld.2. Hanger to suspend pipe while JB Weld set evenly at the bottom.


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1. End of oak dowel with O-ring and piece of twine ready to be charred.2. Treaded end of bicycle wheel spoke.3. Barely visible, trusty old glass file.4. Pocket Ruler5. 1mm drill bit6. O-ring lubricant7. Vice Grips used as temporary handle and originally as a piston stop.8. Handy dandy hand drill9. Hack saw blade and JB weld - not shown in this photo.10. Aluminum piston with O-ring11. Piece of dowel and tissue with Bar Keeper's Friend used to polish inside ofbrass.12. O-Rings13. Cotton twine used to make char twine.

Step 3:Polishing the cylinderDo not use cylinders with a weld seam left inside but only nipples that have been bored smooth at the factory. Otherwise you will have to bore out the inside of the pipremove the excess material remaining after the seam was welded.

I used a 1/4" power drill and a 1/4" oak dowel with an inch wide piece of damp tissue wrapped around it for polishing. I used various grades of sandpaper for honing firsince the nipple was dented or had internal high or low areas resulting from the equipment used to keep the nipple from slipping while the threads were cut.

The tissue was dampened with a solution of water and Bar Keeper's Friend (oxalate acid), inserted into the nipple and spun by the drill. The nipple can become quite hso wear rubber or leather gloves to prevent pain and give a better grip on the brass. Also, stop frequently to add water or more solution to help keep things cool. Adjusthe width and amount of tissue wrapped around the dowel will help to optimize the fit and lower the degree of friction. The more you polish the better, but 10 minutes oless should be enough if your last job of honing was with extra fine grit sandpaper.

Image Notes1. Weld seam - excess material left by factory - bad!2. No weld seam - nipple bored smooth - good!

Image Notes1. Slot cut through dowel with rotary tool and slightly indented on the left of eachside to help accommodate the fold.

Image Notes1. Dampened with a little water and some Bar Keeper's Friend (oxalate acid)


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Step 4:Putting on the end capJB Weld is used to fill in the space where the nipple does not reach the bottom of the end cap. If the space is not f illed the O-Ring will expand in this space and releasthe air pressure too soon as well as get caught in the space.

The end cap is set down like a cup and filled halfway with "steel" and half way with "hardener." They are mixed with a matchstick or toothpick. Then the nipple is heldupright and the bottom end threaded into the end cap and tightened. Once tightened the nipple and end cap are either hung by a str ing or stood up so the JB weld willwith a flat and horizontal surface on the inside to stop the piston and to eliminate all unintended air space.

The hard part comes next - waiting the full 16 hours for the JB Weld to set completely.

Image Notes1. JB Weld mixed in 50/50 part ratio.

Image Notes1. Kept upright and perfectly vertical so JB Weld will set perpendicular to thelength inside the nipple.

Image Notes1. If not filled with JB weld then the compressed air escapes before it iscompressed enough to set the char cloth alight.2. No space for the compressed air to escape so it can be fully compressed andignite the char cloth.

Step 5:Cut the hollow and the seatOn the very end of the piston a hollow is cut using a rounded or squared end drill bit. The hollow may also include 1mm or 1/16" hole, drilled in the center for a total deof no more that 1mm or 1/16" to help hold the char cloth or twine better. Commercial versions may use a slightly deeper (3/16") hollow with no center hole and with theRing set back behind it for practical use in the field.

For construction of this firepiston I just wanted to see if it the limits of the science and technology that might keep it from working. I tried several other configurations. Ycan experiment with all sorts of arrangements, including a double O-Ring configuration. Feel free to experiment and learn everything you can in case you ever really nto make one of these out in the field!

I cut the seat for the O-Ring next by placing the other end of the piston in a 1/4" power drill and using a hack saw blade, glass file and the threads of a bicycle wheelspoke as lathe chisels.

The O-Ring is and seat are next lubricated and the O-Ring is slid on and the O-Ring fitted to the inside diameter of the cylinder.


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Image Notes1. This test piston only has a shallow hollow for testing and not the deepercylindrical hollow for field use. Image Notes

1. For field use the O-Ring seal would be placed further back and the hollowmade cylindrical and deeper.

Step 6:Test the fit of the piston and O-RingWhile it should not be diff icult to insert the piston and O-Ring into the nipple there should be obvious resistance from air pressure and the piston should spring back whreleased. If not try a little more lubricant.

If the piston can not be inserted then remove all lubricant from the shaft and O-Ring, slide the O_Ring up onto the shaft past the seat, put the piston back in the drill anspin the O-Ring on some sandpaper to reduce the outside diameter of the O-Ring a very small amount each time.

Re-lubricate and re-seat the O-Ring and try again. Repeat this process if necessary.

Image Notes1. I used some extra brass nuts I had lying around originally as the anvil for thepiston stop.

Image Notes1. Round O-Ring sanded down to make it fit into the cylinder better.2. Very deep O-Ring seat cut to accommodate inexact O-Ring size. Seat is cutmuch further back for field use and hollow is cylindrical and deeper.

Step 7:Add handlesSince I was not planning to use this in the field (just yet) but rather testing compression ratios I used vice grips as an adjustable piston stop and for the piston handle aa towel to hold the cylinder. For field use you can used pieces of wood with a hole drilled in them the size of the outside diameter of the piston and the outside diametethe cylinder and secure them with epoxy.


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Image Notes1. Vice Grips used originally as adjustable piston stop to control compression ratio... used now as temporary handle.

Step 8:Insert char cloth and testChar cloth is cotton or denim cloth that has been placed inside a closed container, l ike an Altoids tin or capped nipple, with a small hole drilled in it about 1mm or 1/16diameter to allow gases to escape. The container is heated in a fire to drive off water and other volatile compounds. I found also that setting a piece of twine alight afteinserting it in the hole and letting it burn down and then capping it just before the f lame went out produced enough char twine on the very end to be set alight by

compression, although for a much shorter period of time.

( Here is an instructable for making char cloth in the field for use with a firepiston...)

A piece of char cloth is inserted in the recess of the piston head and the piston is inserted into the cylinder. A rapid motion is used to drive the piston forward with greaforce and then withdraw immediately (but with some slight delay).

When withdrawn a small ember should be found which must be nurtured if used to set a piece of tinder alight in order to build a fire.

Do a Google search on the keyword "firepiston " and you can find hundreds of sites on the internet that discuss how to use a firepiston and find videos that show theglowing ember and how it is used to light tender and start a fire. If you have an Adobe Flash Player or add-in you may also be able to view this .

Mine works but until I put on handles I'm not going to develop an operating technique. I have learned that a slight delay after plunging rather than a sort of very rapidbounce worked much better. Experiment.

Image Notes1. This was made from cotton twin rather than cloth and this batch is no goodbecause the end cap melted off and exposed the char twine to air while it was stillhot. I'm testing dried potassium nitrate and water soaked coffee filters next...

Image Notes1. Char cloth or other easily ignited starter..
http://www.thenakedscientists.com/HTML/uploads/tx_naksciimages/firepiston_02.flvhttp://www.instructables.com/id/Instructions-on-how-to-make-charcloth-for-firemaki/


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Related Instructables

Illustrated &Detailed GuideTo Making A

Fire Piston by

jphphotography

How to make a

fire by

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Instructions onhow to makecharcloth forfiremakingusing flint+steel

or firestick. by

garethllewelyn

How to start afire with a

flashlight. by

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WaterproofEmergency FireTinder Bundle

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Comments

50 comments Add Comment view all 77 commen

dkop1 says: Oct 11, 2010. 11:07 AM REPI love my fire piston. I got mine from Wilderness Solutions, (the "Scout" model)and it's never failed me. It did, however, take me a long time to learn how to turn that ember into a roaring blaze. I've never had problems lighting a fire, buwas accustomed to using flint and steel, or ferrocerium rods.Any suggestions on natural tinder for fi re pistons though? all I've ever used is char-cloth.

The Lightning Stalker says: Feb 1, 2008. 9:09 PM REPThis is something I'll have to do in the future. It combines technical things with fire which is an irresistible combination. It'd make a great grill ignitor (I like to

grill with real wood)

spylock says: Oct 21, 2009. 8:33 AM REPI dont know if you have heard of this,not very technical,but take paper egg cartons fill with sawdust or dryer lint then pour melted wax into eachsection,when cooled seperate them,they will each burn about ten minutes,a little longer if useing sawdust.

The Lightning Stalker says: Oct 21, 2009. 2:03 PM REPYeah, actually knapweed and grass clippings work well for that also. There's actually an instructable on it.

tictaclad says: Sep 12, 2010. 2:44 PM REPI take a paper towel, fold it 4 times so its like 1 inch wide ( you have to tear the paper towel) and then soak most of it in wax. leave a little bitwithout wax so you can light it. they burn for like a candle.

franklinonline says: Oct 31, 2009. 8:54 AM REPHave you tried nitrate soaked paper? if it doesnt blow it up, you might get a open flame? Nice lighter with nature fuel possible if you fuel ran out.

spylock says: Oct 21, 2009. 8:17 AM REPThis is where Ive been making my mistakes,I didnt fill the cap,none of the other people told me of this step,thanks.

jphphotography says: Aug 16, 2009. 5:59 PM REPI've been looking through all the info on the net on fire pistons and how to make them. I have to say for how simple they look they are fiendishly difficult tomake. I finally ordered one so I had a starting point LOL. I'm getting closer now, the current prototype works but not consistently enough for me. Hopefullyafter a few tweaks it'll be solid and I'll post my own instructable. Another thing I noticed is that some of the materials listed in various fire piston how to'saren't easy to find. For example the longest brass nipple I can find is 4", other people used copper pipe but I can't find anything smaller than 1/2" so its beea challenge just to get the materials let alone getting it to work. Its all fun stuff though!

forlack says: Jul 15, 2009. 10:52 PM REPDigging into that website Melon gave down there in the comments, NASA gives you two formulas based on the laws of entropy that you can use to calculathe temperature due to volume changes.

The first is to calculate the pressure change due to the compression ratio (or volume change)p2 / p1 = (v1 / v2) (gamma)

Knowing that you can then use the second formula which relates pressure change to temperature change.

T2 / T1 = (p2 / p1) ( (gamma - 1) /gamma)

"Gamma" is just a number that depends on the gas. For air, at standard conditions, it is 1.4. (this is a simplification)

For the full workout go to http://wright.nasa.gov/airplane/compexp.html .Now obviously this has some simplifications, but it should get you a good approximation. Plus their breakdown is for pistons in general which is good.
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BTW Temperature is in Kelvin. Using the above equations and with the following:

Compression ratio of 25:1; initial temperature of 25c. The final temperature will be equal to 807c...pretty hot.

jphphotography says: Jul 5, 2009. 8:59 PM REPHow did the potassium nitrate saturated coffee filters work? Back in high school we used to make smokebombs with that stuff and we'd soak newspaper insaturated solution of potassium nitrate to act as a slow burning fuse.

Fred82664 says: Mar 6, 2009. 4:02 AM REPCool I will have to try this out,Is this the same principle that some Diesel Fuel engines start up ( the ones that do not have glow plugs ) ?

Speedmite says: Mar 9, 2009. 8:37 PM REPGlow plugs heat up the engine when You start up a diesel. Thats all they do. Once the engine is hot, the pistons compresses the fuel and that plus thelittle bit of heat makes it work. I also do not know of any diesels without glow plugs, but it could be possible in hot areas. I'm a teenager thats a nerd andoes nothing with trucks and I can tell you that. Sorry I did that. It just bothered me. and yes, its kind like that, but this isnt as powerful as a diesel and alighter is easy to me compared to this. Just saying.

Fred82664 says: Mar 10, 2009. 8:52 AM REPcool I like to see the younger generation thinking about other things then sex drugs and rock and role. there all good ,but I am in my 40s I know abothe glow plug thing probably be for you was a twinkle in your dad's eyes. ( not meant to make ya feel bad ) older farm tractor did not use glow plugssome of the old Mac trucks and mil itary vehicles did not use glow pugs. I think the use of glow plugs came in around the 60s ,I could be wrong on ththought as well as my thought that friction created the heat to light up the diesel fuel

by all means continue to feed your mind better things then drugs and Challenge current technology make it bettermake new ! (lol my life in some olfolks home may be much better by you doing it lol)

difflock says: Apr 13, 2009. 7:14 AM REPYou are correct. Not all diesels do have glow plugs... Early diesels were just cranked over repeatedly, which created enough heat due to thecompression to start the engine. However, cold weather made it hard to start the engine especially when high compression/high speed dieselengines appeared. Glow plugs were the most successful method of starting diesel engines in cold weather. Some of the methods used before asolid fuel blocks that were fitted into the cylinder head (rudementary glowplug), intake heaters (increase incoming air temp), and introducing ethinto the intake. Some example of pre glow plug diesel engines are: - Field Marshall tractors (large single cylinder 2 stroke diesel) which used asolid fuel block, and then later a stogun cartridge style started which ignited fuel in the cylinder. -Stationary diesel engines, like Petter's andLister's, which are low speed engines that didnt need glow plugs or heater - I believe that the Detroit Diesels featured the ether intake system.Hope that helps. By the way, I'm 19, but have been interested in old engines since I was born :P Old tractors that used TVO still produce thenicest smell :)

Fred82664 says: Apr 13, 2009. 7:41 PM REPYes this dose to you young lad you have my honers. you have done well in your studying and investing your knowledge to better living andonly 19 at this point of time. I can see much more grate things coming from your efforts in the years ahead of you ! keep it growing

Speedmite says: Apr 14, 2009. 1:24 PM REPThank you.

difflock says: Apr 13, 2009. 7:22 AM REPA youtube video of a Petter PAZ1

http://www.youtube.com/watch?v=Xp3gIpKnswQ

You just crank the engine over and then fl ick the decompression lever...causing the engine to rapidly compress air causing heat...

sharlston says: Mar 9, 2009. 10:41 AM REPany more ideas please email them to [email protected] this is so cool

K.hall86 says:Feb 1, 2008. 3:20 PM REP

have you experimented with a stainless rod?? the stainless would have more resilience, although you would need more advanced cutting tools. although ymight also need to experiment with the width of the o-ring grove...i can see the grove depth and width playing a key role in this. i would assume that theoptimum grove width and depth would be the diameter of the ring. that way the ring would have no "slop" in the thrust direction, and it would also guard thering from trying to roll out of the grove....i am of course assuming a lot here...lol you might try making a piston in very large scale at first....large diametershave tons of structural integrity..it might help work out the kinks in the small scale experiments...

n0ukf says: Nov 14, 2008. 1:53 PM REPHave you ever tried to work with stainless? it's tougher to cut than regular mild steel (which is tougher cutting than aluminum)
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watermelon says: Feb 3, 2008. 2:50 PM REPI use to carry stainless steel mini mess kits. It is not until you add things up that weight becomes a factor. Aluminum rod has enough strength andcorrosion resistance plus workability to make it an excellent material for the job, especially for field use were weight is a factor. Commercial units use avariety of materials. The purpose of testing various configurations is to optimize your own personal firepiston to match the characteristics you need - likbuilding a bow to match your height and strength.

chi chi chippy says: Sep 28, 2008. 7:55 PM REPi have tried to make own out of pvc i saw on a website but i cant get it to start the tinder any one got any suggestions

watermelon says: Sep 29, 2008. 6:50 PM REP

You can always make the length longer to gain a greater compression ratio, but PVC is not a material I would use due to the temperature at which itbegins to soften and the low pressure at that temperature required to deform it. Clear polycarbonate, however is often used to make demonstrationmodels. You might also consider making one out of a chunk of wood or a piece of bamboo. The lignin which binds the cellulose fibers in wood togethervery resistant to degradation.

SPININSPUR says: Aug 25, 2008. 9:32 AM REPhas anyone come up with one small enough to be put on a key chain. How small can one be made so that the compression aspect is not compromised.iwould like to make one as small as possible to carry.

chi chi chippy says: Sep 24, 2008. 5:55 PM REPyou can make one as small as you want but the smaller, the less t inder (char cloth/twine)you can use. i mean ive seen one as thin as a pencil.

Kinnishian says: Feb 2, 2008. 12:33 PM REPVery nice guide. But I think explanations are overcomplicated.

Just for one simplification that anyone with some algebra could understand involving why it gets so hot.

Use the formula PV=nRT

Where P = atmospheric pressure. V = volume of gas (air). n = atoms of gas in mols. R = gas costant .0821 and T = Temperature in kelvin.

Keeping in mind P, n, and R remain the same anyone can determine T with simple algebra.

You can use suggestion or not it's still a good guide.

wizodd says: May 2, 2008. 6:26 AM REPEasier than that. You need a compression ratio of about 25:1 Calculate the volume of the cylinder. V Calculate the volume that remains with the pistonfully in. Vc V:Vc should be 25:1 or more. Note that the wider the cylinder and the smaller the tinder hole, the shorter the stroke length. Nearly anymaterials can and have been used to make these. The ones for sale on the net are art pieces-like custom knives. When the Brit ish first found these, thecouldn't believe that they hadn't been invented somewhere 'civilized' as they found them pretty much everywhere the blowgun has been invented. Theywere just becoming very popular in Europe when the match "lucifer" was invented. Despite the then major disadvantages of the match (early ones

tended to light TOO easily, like in your pocket!) Once you've got one they have a number of advantages over the standard lighters ('flint' & steel) in thatthey are wind and waterproof--if you're not actually under water, it will ignite, and more reliably than most lighters. No fuel to buy as nearly anything thais fluffy and burns will ignite.

watermelon says: Feb 3, 2008. 1:15 AM REPThe math is quite a bit more complicated than juxtaposing the Equation of State for an Ideal Gas, as the Adiabatic process involves the Laws ofThermodynamics and must include the Enthalpy Equation. (See Entropy of a Gas )

Kinnishian says: Feb 3, 2008. 2:05 PM REPHmm....Alright :-) My mistake then. We covered the basics of gases earlier, and now we're into enthalpy and entropy. But, I don't think we've putthem together yet. My favorite class it tis... Is the difference in the mathematics considerable? Oh, and I suppose we just started trying to determinethe K constant for entropy. But I don't understand that yet. Maybe I should go do my homework now :p.

watermelon says: Feb 4, 2008. 12:35 PM REP

Detroit would most likely hire an engineer at a high wage who could model a firepiston mathematically.

Kinnishian says: Feb 5, 2008. 2:49 PM REP...=/

I was just trying to ask how accurate 'my method' would be?

And you know. So, right, thanks.
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11/12


watermelon says: Feb 5, 2008. 7:19 PM REPSometimes in school teachers will make it seem like if you learn only what they are teaching at the moment that you will know everythinthere is to know and that there is nothing beyond unless youcome up with it. Then all of the sudden its like walking off a cliff when youfind out they only scratched the surface. The pressure, temperature and volume relation of a gas is important to know but that is far fromall there is. Check out air conditioning and refrigeration systems. A repair technician could probably help you to understand what happenwith temperature when a gas is compressed at various ratios. Those are the guys I would ask.

shadeofsound says: Sep 10, 2008. 12:37 AM REPso incredibly true there

Senseless

says: Feb 2, 2008. 7:46 AM REP

Dang nice Instructable. It reminds me of an old pump design that let's you lift a small volume of water ten feet using a larger volume of flowing water like froa stream but without the need for it to drop like a typical dam system uses to generate force. I can't remember the name of the thing it's been around sincethe 1800's or so. This will bug me all weekend now trying to remember what it was called LOL.

Saint_Awesome says: Feb 22, 2008. 5:44 PM REPWe call this a 'waterfall bong', check out youtube for more.

wgrover says: Feb 2, 2008. 3:41 PM REPHi Senseless, it's a hydraulic ram if I'm not mistaken:

Hydraulic ram

Senseless says: Feb 2, 2008. 4:36 PM REPThanks! That's it exactly! I'll be able to sleep tonight LOL. It's like getting a song stuck in your head...

harry hardcore hoedown says: Feb 10, 2008. 3:32 AM REPWow,

incorrigible packrat says: Feb 6, 2008. 7:20 PM REPNeato. I wonder if one could be made from a hatchback lift assist cylinder, or maybe one of those l ittle pneumatic cylinders from the surplus store.

watermelon says: Feb 7, 2008. 5:29 AM REPSometimes the only way to find the answer is just to save up the money to buy the parts and then when you have some time to do i t.

twhaley says: Feb 2, 2008. 7:27 PM REPNeato, i'm gonna try this tomorrow. If it works i'm gonna use it to light my farts on fire. Thanks Mel!

Johnsons on fire says: Jan 28, 2008. 5:56 PM REPvideo?

watermelon says: Jan 29, 2008. 1:32 AM REPThis instructable was made for those who only want to make their own f irepiston to be sure in their head that the science and technology work and whodo not want to spend $50 and upwards on something they can make themselves at much less cost.. A Google search will score tons of video at sitesready and willing to pluck $50 out of your pocket. Video production was not included in my budget since I have no intention of selling firepiston kits.

Johnsons on fire says: Jan 29, 2008. 1:06 PM REPi only want a video of you working it... is that too much to ask?

watermelon says: Jan 29, 2008. 6:31 PM REPDid you read the very last sentence of Step #8? It reads, "Mine works but until I put on handles I'mnotgoing to develop an operating techniquehave learned that a slight delay after plunging rather than a sort of very rapid bounce worked much better. Experiment. "

I have added your request to the PERT . However, development and demonstration of a proper operating technique must followthe milestone omaking proper handles and the milestone of making a cylindrical hollow, along with selecting materials possessing the most suitablecharacteristics and dimensions. Development and demonstration of a proper operating technique would be premature before then.

Also, operation is as much an art as it is a mechanical technique, no dif ferent than the operation of various vehicles is generally unique, where demonstration particular to one would be misleading for another.

In answer to your question, yes, a video of you receiving your driver's license at age 16 when you are still 15 is too much to ask.
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12/12

htt // i t t bl /id/St t fi ith i /

Senseless says: Feb 2, 2008. 7:50 AM REPI understand that explanation completely which scares me... Just remember, you don't actually need a license to drive a car... Perfection is agoal but not a necessity.

watermelon says: Feb 2, 2008. 11:32 AM REPPrecisely and just because you can drive a car does not mean you are old enough to have a drivers license. Consequently, it is too mucto ask for a video of you driving a car and receiving your driver's l icense while you were still not old enough to receive your drivers licenseven though you can drive a car. Some people would say it is okay so long as you made it clear that the video was only a depiction offuture events, rather than the event i tself. By the same token, if you are in the process of testing various aspects of a mechanical designincluding its operation, then it might be inappropriate to produce a video for show and tell of it operating at a compression ratio of 43:1rather than at it's target ratio of 25 to 1. Avoiding any chance of video deception here, however, may be the necessary goal, rather than

product of perfection.

static says: Feb 2, 2008. 12:36 AM REPGood job on an interesting uncommon project. Like another I thought that a larger diameter may make construction easier, then it dawned on me that woulrequire extra force to compress the air. Have you looked into finding or creating a cup like piston, where the air pressure would force the cup walls againstthe cylinder wall making for a tighter seal? I think the oil field supply store here sell seamless brass nipples, that may make it easier to make a good bore

watermelon says: Feb 2, 2008. 2:13 AM REPOne of the reasons I dri lled the char cloth indent or hollow so shallow was to get a higher compression ratio since the longest nipple available to me offthe shelf from my local plumbing store is 6". Since the piston head takes up at least 1/2" that only leaves me with 5.3125 inch height and a 0.1875 inchchar cloth hollow or a 28:1 compression ratio. versus a 5.375 inch height and a 0.125 inch char cloth hollow or a 43:1 compression ratio. Commercialunits use a 25:1 compression ratio with a 3/16" char cloth hollow. Experiment.

JerBear says: Jan 28, 2008. 6:11 PM REP

Whoa! fire with air! nice!

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