Introduction: Brake Disk Forge

Picture of Brake Disk Forge

So here you have a basic forge. It's nothing beautiful but it does the job and that's all I was looking for here.

Most of it was scrap but I did purchase some of the parts. Not counting what I already had, I spent about 40 bucks.

Now you can craft your own knives, tools, and decorative bird feeder hangers for the wife.

(The idea and design for this forge were obtained from an Ag teacher's YTube video.)

Step 1: Gather Supplies

Picture of Gather Supplies


  • Brake Disk or Rotor (I used some warped Rotors off my car)
  • Scrap Metal for the Stand
  • Floor Flange, Tee, Cap, and 3 couplings (I purchased mine at HD)
  • Rebar for blacksmithing
  • 4 bolts, washers and nuts (bolts need to be minimum 1 inch long)
  • Drill and bit
  • Mortar (only about a cup)
  • Scrap metal with holes in it (clinker breaker)

Air Source

  • Tin Can
  • A blow dryer that doesn't work.
  • On/Off switch ( I used a sewing foot pedal)
  • Soldering Iron/Solder
  • Alligator clips
  • Battery (I used a dewalt 18v battery)


  • Lump Charcoal (Best Option)
  • Regular Charcoal (Burns fast so have a lot!)

Step 2: Forge- Attach the Floor Flange

Picture of Forge- Attach the Floor Flange

Flip the rotor upside down and mark the holes for the floor flange.

Drill the holes.

Step 3: Forge- Connect the Pipe

Picture of Forge- Connect the Pipe

I used Galvanized pipe that was 1-1/2 inches in diameter.

I purchased it all at HD for around 30 bucks.

Step 4: Forge- Fill in the Gaps

Picture of Forge- Fill in the Gaps

The first time I built this forge, it didn't get hot enough to make the metal glow. An experienced blacksmith told me that the air was escaping through the holes.

Pour some mortar mix into a Dixie cup about halfway. Add water until its like peanut butter and patch all the holes with a plastic knife or your finger. Besides the pipe coming out, it should be air tight.

Throw the scrap metal with holes in it over the hole to keep hot coals from falling out. This is called a "clinker breaker."

Step 5: Air Source- Find a Hair Dryer That Doesn't Work.

While this main seem crazy to find a Hair Dryer that doesn't work, let me explain.

Hair dryers have several diodes, and resistors that make up the connection to the motor. For safety, all of these things connect in series so that in the event that any one of these components burns out, the circuit is broken. It's a safety feature.

Since many of these components are cheap, it is likely that the motor is still good.

Step 6: Air Source- Open Up the Hair Dryer

Picture of Air Source- Open Up the Hair Dryer

Unplug the hair dryer first!!!

Cut the male outlet off. (If you cut it about halfway, you can use the plug for another project)

Open up the dryer by removing the three screws and find the motor. Motors are very simple containing only positive and negative posts. Cut off the wire attached to the posts. Solder the wires to the posts like the picture.

Connect the battery to the positive and negative. (If the Hair Dryer doesn't blow in the correct direction, reverse the connection.)

(Note: It is a lot of work to strip out all the wires and insides of the Hair Dryer. It took me about 30 minutes with a pair of pliers. I saved the diodes and made a bridge rectifier for an electrolysis setup but it's easier to pull the motor, solder the wires, and put it back in.)

Step 7: Air Source- Connect the Switch

Picture of Air Source- Connect the Switch

Following the example in the picture, connect the hair dryer directly to the battery. If a switch isn't available just direct connect to the battery with alligator clips and remove it to turn it on or off.

Step 8: Forge/Air Source- Connect the Bellows (Hair Dryer)

Picture of Forge/Air Source- Connect the Bellows (Hair Dryer)

Cut a metal can so you can connect the Bellows and Forge. A pam cooking spray can is the perfect size. The first one I used was a metal Goat Milk Can.

(Note: I tried using PVC and it was melted soft in about 2 minutes)

Step 9: Fuel- Lump Charcoal

Picture of Fuel- Lump Charcoal

Ok, so someone out there will argue that regular charcoal is just as good but they are wrong. I have used both and even tried wood but nothing is better than Lump Charcoal.

My friend knew a guy that could provide "straight from the earth" coal and it worked beautifully except for the hazardous fumes produced in the first 5 minutes.

Lump Charcoal can be found in grilling isle next to regular coal. It will look like rock and sound like broken glass when you shake the bag. Oh yeah, and it's labeled "Lump" Charcoal.

Step 10: Fire It Up!!!

Picture of Fire It Up!!!

Don't bother worrying about the mortar drying and fire it up. Trust me it won't take long for the mortar to be baked crispy.

My 18volt dewalt battery powered the bellows (hair dryer) perfectly and lasted long enough so that I didn't have to change it. At 2 minutes the metal was hot enough to hammer flat.

For starters you will need:

  • An anvil or other hard surface
  • Hammer
  • Pliers or Vice Grips
  • Eye Protection
  • Gloves



bladesmith9568 (author)2016-11-24

Dont use galvanised steel! heat can cause it to release poisones gas

But very good instrucatble

Dave85 (author)bladesmith95682017-01-14

The galvanized steel seems to be a popular topic. No one mentioned that the carbon dioxide as being a deadly toxic gas. The galvanized is a non-issue.

ShalorM (author)Dave852017-11-13

The galvanized is worse than the carbon dioxide because you breathe in CO2 all the time and as long as it isn't in huge quantities it doesn't matter, zinc fumes will give you welders lung, which is a lot like the flu, but much much worse.

Dave85 (author)ShalorM2017-11-18

No the CO2 is worse. The zinc is only a coating and burns off within the first couple of burns. The CO2 is given off every time.

AR1911 (author)2015-12-19

Good article, but you stopped to soon IMO. What is the heat source, and how is it connected? I presume it's propane or natural gas coming in at the bottom of the vertical pipe. I see from the photo that the blower comes in at the side through the tee. Is there a propane hose entering the bottom pipe? Sealed somehow to keep the air from exiting out the bottom?

Dave85 (author)AR19112016-03-25

A fan blows the air on a charcoal fire increasing the heat. The bottom is capped to prevent air leaving.

williamm192 (author)2016-03-16

Whoah can we focus on a real issue here!!! Do NOT use Galvanized pipe anywhere in this project or you will be risking zinc poisoning from the fumes when the metal heats up in the pipe. Its not a lot in this case and it seems to be outside but everyone needs to do their research because this is something that can kill you over time. Galvanized metal should be avoided when application is going to see temperatures this high.


Dave85 (author)williamm1922016-03-25

Your issue has already been addressed and mentioned in the instructable.

ardrhi (author)2015-05-12

Thank you from the bottom of my twisted little soul for NOT saying "break drum". Every time I see that, I want to punch a kitten.

Dave85 (author)ardrhi2015-05-13

Yes. I was very careful. I've always called them "rotors" but the rest of the world (auto stores) calls them brake disks. I had more trouble with "hair dryers" as I've grown up calling them "blow dryers" which sounds odd.

studiogrynn (author)Dave852015-12-25

I am right there with you. Always called them rotors, and blow dryers.

mrmadison (author)ardrhi2015-05-12

Uhhh. Let's go with BRAKE ROTOR. That's not a "break" nor is it a "drum"! We need to save the kittens from ardrhi! ;-P

ardrhi (author)ardrhi2015-05-12

(I don't really want to punch kittens, I love kittens. I just really, really hate it when people get that wrong.)

Kevanf1 (author)ardrhi2015-05-12

Quite, only very aggressive drummers 'break drums' :) Welcome to the wonderful world of the grammar police :D

ardrhi (author)Kevanf12015-05-12

No policing involved. Just grateful to see someone pay attention to detail.

nwonharp (author)2015-07-24

As far as old hairdryers go , a lot of them had a " thermal fuse " in them which would burn out and keep it from running as a safety feature , so that if it overheated , it wouldn't catch fire and burn your house down . As far as I could see , the most common cause was that the air intake vents would get clogged up with lint or hair , and the heat couldn't get out . The thermal fuses cost about a dollar or so :

But using it outdoors with a forge , the hairdryer catching fire is probably the least safety hazard you need to be concerned with !

Take care !!

HowToWut (author)2015-05-21

I made one like these. Except I used a brake drum. The big deep welled brake bit, just had it rusting away. I havent mortared it up yet. Andi actually spliced the hair dryers wire into a garbage disposal switch. Which its only on as long as its being pressed down, which I just made a little wooden petal for it. And its very cool indeed. I've made a rose out of 1/4 mild steel round stock.

paul444e (author)HowToWut2015-06-06

I would love to see the rose and an inscrutable would be awsome

Dave85 (author)HowToWut2015-05-26

Great comment! You've shown your resourcefulness. In truth you could probably make a forge out of any material. I've thought about wire mesh, newspaper coated with plaster sand mixed at a 1:1 ratio. You should create an instructable on how to make the wooden pedal or the rose. I'm sure that many viewers, including myself, would like to see that.

gpender (author)2015-05-25

What about the clinker breaker? Does lump charcoal not make clinkers? Either way what happens to the ash/waste?

Dave85 (author)gpender2015-05-26

Wow thank you for the comment! I've updated the instructable with a pic and instructions for a clinker breaker. The ash falls down into the tube and the cap can be removed to empty out the ash.

Dave85 (author)2015-05-17

Thanks for clearing that up.

oppie (author)2015-05-14

Check out the site and especially the iForge page. If you get into blacksmithing at all, this site is a great resource.

I have a forge built along the same lines but using a drum brake rather than a disk brake. It came from a local repair shop as scrap. Much deeper and wider.

Seth of choas (author)2015-05-12

my primary concern with this would be that when galvanized pipe heats up it starts producing zinc fumes which are lethal in unpleasant ways.

Is is possible for something to be lethal in a pleasant way? :)

joeterrier (author)matstermind2015-05-12

I wanted to say that.....

But actually YES.....

or so the TV tells me....

2 words (10 syllables) comes to mind...

toofat2serve (author)joeterrier2015-05-13

Autoerotic asphyxiation?
Is it messed up in any way that I guessed that instantly and correctly? :p

joeterrier (author)joeterrier2015-05-12

as far as the risk, very minimal. i doubt the pipe gets that hot. if i understand correctly he used mortar to seal the rotor so there is a clay layer on the bottom and the pipe is outside the rotor.... well away from the fire.

i'd use more mortar and form a bowl in there....

great design though

Seth of choas (author)joeterrier2015-05-12

even then, personally I wouldn't risk it, but thats me. If there haven't been issues in the system they described then thats good for them.

robbhammack (author)matstermind2015-05-12

well, there WAS this one ex-girlfriend....

very toxic, but sometimes pleasant. Longer expose would have proven leahal I'm sure :)

there are several ways to die that are more pleasant than heavy metal fever :p

stoobers (author)Seth of choas2015-05-12

This will only happen for a little while. You will see it as yellow smoke. Don't eat yellow snow, don't breath yellow smoke, etc. If you don't see the smoke and you don't stick your head over the flame and inhale the 1500 degree smoke, you won't get sick.

This yellow smoke can burn and make zinc oxide, which isn't as toxic as gaseous zinc metal, so it isn't too big a deal, considering everything coming out of a forge is either toxic or dangerous.

But it is a pretty, mustard yellow smoke.

Kevanf1 (author)2015-05-12

Wonderfu, well done. I wonder? Have you ever thought of making a forge using a brake drum as opposed to a disk? I'm thinking of an old one off a large lorry or truck..

Dave85 (author)Kevanf12015-05-13

Thank you for your comment. Yes I have considered using a brake drum and the video of the Ag teacher on YTube does it that way. I made this utilizing materials I had on hand except for the galvanized pipe.

GaryJ1 (author)2015-05-13

Very nice work but galvanized pipe is a bad idea, emits poisonous off gasses when hot. I am making a Break Drum forge but I will use black iron pipe, I have the drum and stand ready, I just need the pipe fittings.

Dave85 (author)GaryJ12015-05-13

Thank you for your comment. The Galvanized Pipe can emit zinc oxide fumes that are harmful and can cause flu like symptoms. In this case, however, the forge is outside and the operator does not stand over the forge while breathing so it's not a major safety concern. To air on the side of caution (pun intended) you could use black iron with the same results.

mf70 (author)2015-05-12

I'm a little confused: Why a brake rotor for the basic frame? Wouldn't a metal box be enough? It makes me want to try it, though...

stoobers (author)mf702015-05-12

If you use steel for the firebox, the firebox will burn through. Cast iron or cast steel has all kinds of stuff in it to allow it to pour when casting, which double as corrosion resistance. The cast iron/steel firebox can take some pretty high heat before rusting away.

joeterrier (author)mf702015-05-12

early forges I've seen in antique shops look like bird bath's made of cast iron. some had bellows others a hand crank blower. its a pretty good design

seamster (author)2015-05-11

Very nice! Thanks for sharing this simple design.

saeb saqer (author)seamster2015-05-12

grate work , thanx for sharing !

sigma472 (author)2015-05-11

I'm looking forward to giving this a whirl. Thanks for sharing the idea!

Logan Hanssen (author)2015-05-11

Great instrucable! This is the most clear forge making instrucable I've seen so far!

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