Simple Fire Piston

Intro: Simple Fire Piston

Make a simple fire piston from off the shelf parts.

For some time now I’ve wanted to make my own fire piston after seeing click springs fantastic version. Unfortunately I don’t have any of the tools that he uses, plus it seemed like a complicated build. After a little research I found that you could make a simpler version with off the shelf parts. Matter-of-fact, you might even have these parts lying around the shed!

For those who may be new to a fire piston, what it does is allow you to ignite char cloth without any form of fire. Once the char cloth is lit, then you can use this to light your fire. It works by compressing and heating air until it reaches temperatures of 260°C (500°F). This is hot enough to ignite the char cloth and create an ember which can be used to light your fire.

In step 7 I go through how to make Char cloth.

Check out this link if you would like to learn more about the fire piston.

It doesn’t take any real skill to make one of these and you only need basic tools. The hardest part is getting the seal right on the push rod. This took me a few goes but I learnt a lot so hopefully you won’t have to waste as much time as I did!

However, it can take some time to perfect using the fire piston. Getting the right action and speed is essential in igniting the char cloth. The last step goes through a few ides to try if your not getting the char cloth to ignite.

STEP 1: Parts and Tools

Parts:

Fire Piston

1. 9.5mm wooden dowel. You shouldn’t have any issues getting this size dowel at your local hardware store. Don’t get pine as it isn’t strong enough.

2. 12.7mm copper tube. You can find this in the plumbing section at your hardware store. If you can't get this size exact, then close enough will do.

3. 2 X 15mm brass cap. Same place you got the tube from

4. 15mm coupling to 15mm male screw. –hardware store.

5. 15mm female screw lid – hardware store

6. O ring. You can get assorted ones in the plumbing section of your local hardware store. The O ring needs to fit tight around the dowel or check out eBay

7. Small brass eye hook

8. Silicone plumbers grease (this is to lubricate the O ring). You can add motor oil but I've been told that this can break down the O ring. You can buy this at any hardware store (plumbing section)

Char Cloth

1. Tin with lid. I use an old tobacco tin

2. Piece of old clothing. Best to use 100% cotton or denim.

Tools

1. Grinder

2. Solder

3. Solder flux

4. Small blow torch

5. Saw

6. Drill

7. Epoxy glue

STEP 2: Cut and Solder the Cap to the Tube

First thing is to decide how long you want to make your fire piston. There is no correct length that you should use but if this is your first one, I would make it at least 150mm long.

Steps:

1. Cut the copper tubing with an angle grinder

2. File and remove any sharp edges.

3. Add some flux to the end of the tube and push on the 15mm cap

4. Heat-up the end with a small blow torch and touch with some solder until the cap is fully sealed to the copper tube.

STEP 3: Attaching the Screw Section to the Tube

This isn’t a necessary part and if you don’t attach it, then the fire piston will still work. The reason why I attached this is so I could screw a lid onto the fire piston and make sure that the rod wouldn’t come out. It’s a good way to store your fire piston as allows you to also carry it easily.

Steps:

1. Add some flux to the other end of the copper tube

2. Attach the screw section to the tube, heat-up with a blow torch and add some solder.

3. Place the cap on top to make sure everything fits ok.

4. Next drill a small hole into the top of the cap.

5. Grab an eye hook and cut off the screw section so only a few millimetres are left.

6. Place the screw section onto the hole, add some flux and solder into place.

STEP 4: Making the Piston

The actual piston is simple as it’s just a piece of dowel. The tricky part is to make the incision the right size so the O ring makes a good seal inside the tube. I tried several times to get this right and discovered that adding a little oil is the key. If any air leaks then you won’t get the compression and heat you need to ignite the char cloth.

Steps:

1. Cut a piece of dowel a little longer than the actual tube. Mine was about 10mm longer

2. Next, put the dowel into a drill and secure the drill so it won’t move. I put mine in a vice to keep it upright. Turn on the drill.

3. The best way to make the groove I found was to use the side of a small, thin file. Push the side of the file against the wood and move it up and down. Take your time and don’t go too deep or wide. The groove should only be as wide as the O ring. You can also use a small screwdriver or something similar to make the groove.

NOTE: TimothyK34 recently made one of these and came up with a good way to make the groove. Just brake a hack saw blade in 2, tape them together and slowly role the dowel along the blade. He said that this made a perfect sized groove for the O ring.

4. Stop and check regularly. Once you have an even groove, remove the dowel and add the O ring to the groove. If the O ring sits even in the groove, then you are ready to see if it fits into the tube. HERE’S THE IMPORTANT BIT. Make sure you add a little bit of oil to the O ring. This will ensure that it moves easily and smoothly inside the tube. I didn’t do this initially and my O ring kept on getting stuck inside.

5. To test you need to push the rod into the tube. You should feel a “cushion” of compressed air as you push the rod down. This will force the rod to bounce back up again. If you find that the rod isn’t bouncing back, or that it’s too hard to push into the tube, then you will either need to make the groove larger or start again. Don’t despair if your first couple don’t work, getting the seal right will probably take a couple turns. You will know though when it is right as soon as you feel the “cushion” of air forcing the piston back up again.

STEP 5: Drilling a Hole in the End of the Piston

To ensure the char cloth has a place to sit, you need to drill a hole into the end of the dowel.

Steps:

1. Secure the dowel into a vice

2. Carefully drill a hole into the end of the dowel. It needs to be about 10mm deep. Remember, it needs to be big enough to hold the char cloth in place

STEP 6: Adding a Cap to the End of the Rod

Initially I was going to attach the copper screw cap to the end of the rod. I decided against this in the end as I thought it would be too hard to attach it to the wooden dowel.

Instead I just glued a small copper cap to the end to protect the wood. I also made another rod and added a nut instead of the copper cap

Steps:

Adding the cap

1. Mix some epoxy up and put it into the cap.

2. Place the end of the dowel inside and leave to dry

Adding a Nut

1. Find a nut that is slightly smaller than the end of the dowel

2. Carefully either screw onto the wood or lightly hammer until secure

STEP 7: Making Char Cloth

Making char cloth is super easy and there are plenty of good instructions on the net on how to make it. The below shows you how to do it. link for more

Check out this wikipedia link to see how it all works

Steps:

1. First cut up some cloth. 100% cotton is the way to go. Cut up the cloth into small pieces.

2. Next grab a small tin like a tobacco tin and make a small hole in the top. Place the cut up cloth into the tin and place the lid on top.

3. Place the tin onto a fire source. You'll start to first see some smoke and then a flames come out the hole. Once the flame has died down and gone out you then should block the hole with a stick. The reason being the char cloth can start to smolder and ignite once it has been removed from the fire.

4. That's it! your char cloth is ready to use in your fire piston.

STEP 8: Using Your Fire Piston

So now you’ve finished your piston, it’s time to get it to work. It does take a little practice but once you get it, it should work for you each time. Don’t be put off if it doesn’t work straight away though.

Here’s what you do:

Steps:

1. Place a small piece of char cloth into the drilled hole in the piston

2. Add a little oil to the O ring. You don’t have to do this each time, just the first time or until the O ring is dry.

UPDATE - As DaBoSSs has mentioned in the comments below, it's better to use silicone grease instead. It won't break down the rubber like motor oil will. However, just use motor oil if that's all you have around - I have been and it seems to do the job well.

3. Push the end of the rod into the piston just to the O ring is inside

4. Now you can either push the piston in with the palm of your hand (which can hurt after multiple times believe me) or do what I did which was:

a. Turn the tube upside-down with the piston touching the table

b. Grab hold of the tube with one hand and put your thumb on top of the tube

c. Place your other hand on top and give the tube a quick push down

d. immediately remove the piston and check the char cloth to see if it is lit

e. If not, try it again until it’s lit

STEP 9: Troubleshooting

If you are having issues getting the Char cloth to light, then check out the below hints

There is no push back (compression) on the piston

You should always feel the piston pushing back when you go to push it in. If not, you may need to try the following:

- Add a little oil to the O ring

- Remove some of the oil by wiping the piston. It can get dirty and you can lose compression.

- Pull the O ring out of the groove, clean it and put it back.

- Re-visit the groove that you added. If you aren’t getting any compression, it could be because the groove is too deep.

- Change the O ring

Can’t get the piston into the tube

- It could mean that you need to make the groove larger. Check and make sure that there are no bumps on the groove and that it is a smooth as possible. It doesn’t have to be perfect though.

- Add some oil

- Check the size of your O ring

I’ve pushed down a hundred times and still nothing

- When you push the piston into the tube you need to make sure that it is a quick, sharp action. Push down hard but don’t try to hold it down, let the piston come up naturally which it will because of the compression.

- Check you char cloth. If it doesn’t light after a few pushes then change it.

- Try a different method. There isn’t one sure way to get the char cloth to ignite so find what works best for you.

Comments

[DaBoSSs]

Didn't see this addressed in the comments I read. Instead of motor oil or other petroleum based oil, use silicone plumbers grease instead. Any petroleum based oil will break down the O-ring, plumbers silicone grease will NOT.

From repairing Fountain pens - many types have either O-rings or rubber ink sacs. If you use petroleum based products you will cause the rubber in the O-ring & the pen sac to break down fairly quickly. Silicone plumbers grease will NO

t cause rubber O-rings to break down. Can get it for $1-2 where you get your plumbing supplies. Any place that carries copper tubing will have it.

[lonesoulsurfer]

Great advice - thanks.

I'll add the information into the ible'

[ColinM26]

1/2-in x Copper Slip Air Chamber Fitting work perfect. https://www.lowes.com/pd/1-2-in-x-Copper-Slip-Air-Chamber-Fitting/3521666

[offseidjr]

Great 'ible! Very detailed!

[yrralguthrie]

Two things.

Most copper tubing in the US is still English sized. Has to be to match older plumbing. Ditto wood dowling. So you may need to experiment to find the right size.

Second I've use lint as a fire starter side by side with cotton balls. The cotton balls are easier to light and burn much more vigorously and longer. lint is naturally of unknown composition. Most clothes these days are treated to not burn, just smolder. Even or especially cotton.

[JasonL237]

5/8" should be close to his 15mm pipe. seems like an easy place to start combined with 1/2" dowel. I think I'd like to try an aluminum rod with a teflon ring, just to see if it would work and last.

[TimothyK34]

it's actually 12.7mm, or 1/2" (it's all been updated now) ....and the dowel is 1/3". Even though we are in Australia, all of the plumbing stuff is the same, we just get it in metric.

[yrralguthrie]

In my part of the US 5/8 copper tubing is going to be hard to get. Perhaps a plumbing wholesale house. Maybe electrical or heat and air.

I'd have to use something else. But nothing critical there.

[derflingerflonger]

I find a good place to get project materials cheap is or out of date is demolition / used building material yards. Bring your own tube cutter and a short piece of copper pipe is usually next to free. Another good place if one is close to you is The Habitat for Humanity ReStore. They usually have tons of used or donated surplus plumbing or other building materials at low prices.

They can usually be found in most major towns and cities.

[lonesoulsurfer]

As long as the copper tube and dowel are around the same size then you should be ok. The dowel should fit loosely into the copper tubing so when you add the O ring it will form a good seal. In regards to lint - yes I have used this before as tinder but no in the fire piston. I'll give a go tonight and let you know if it works

[TimothyK34]

Sure add it to your 'ible when i did it i just drew a line on the dowel and slowly rolled the dowel along the table didn't put it in a drill worked really well.

[TimothyK34]

Lonesoulsurfer you would not believe how happy I'm it works it works it works i love it when something you makes works. Great 'ible buy the way. Oh and by the way the best way i found to make the groove for the o ring was to snap a hacksaw blade i half and tape them together made the perfect size gap for me. My flat mate is making one as well so when we are finished we will upload some photo's.

[lonesoulsurfer]

That's excellent! I might include your way to make the groove in the ible' if that's cool.

Post some photos too when you get a chance.

[TimothyK34]

lonesoulsurfer i have just been to bunnings and iam sorry to say that you have made a mistake with the size of the copper tube it is actually 12.7mm. have a look at the picture you posted in step 1 parts and tools and in the photo bottom left you can clearly see it says 1.5 x 12.7 x 0.19 straight copper tube. Every thing else fits perfectly including the 9.5mm Tasmanian oak dowel. So hopefully my fire piston will work as good as yours thanks for the great instuctable

[lonesoulsurfer]

Oh and let me know how your fire piston goes. More than happy to help if you get stuck in any place.

[lonesoulsurfer]

Thanks for the heads-up. I've updated the ible'.

[TEAMPANIC42]

3/8" roughly equates.

[yrralguthrie]

3/8" what? Tubing or pipe.

3/8" copper tubing is generally not rigid. Pretty hard to make it straight enough.

There is really no reason to stick to any particular size. Just match the tubing to the dowel. Or in my case I'll just make a dowel to fit whatever I have handy.

[derflingerflonger]

As long as the gap is tightly taken up by the "O" ring it shouldn't matter too much about tube diameter. I made one using two "O" rings spaced about 3/8", (10 mm) apart. works like the piston in a diesel engine. Great example of pressure induced heat . I love it and you know a lighter never works when you need it . My concern though, judging by some of the comments I've read is whether or not such an incendiary device as this should be in the public domain. Keep on supplying us with great projects.

Thanks DJ

[clevedon6]

We English use metric units, ie. millimetres, The US uses imperial units, ie. inches.