DIY Forge




This is my version 2 forge I made specifically for making my knife (instructaable coming late june). my version one was not worthy if an instructable. I've only done this once before and my last one was terrible, so let me know if there are any problems.

Step 1: What You Need

You will need

  • Post hole digger (optional)
  • Shovel (not optional)
  • 6" duct pipe 90º elbow (not optional either)
  • 6"-4'' reducer
  • Some land you can dig up
  • A leaf blower or some other powerful fan

Step 2: Dig Yo Hole

Dig a hole about one foot deep at the forge end and 6" deep at the other end. assemble your pipes and put them in to check your depth.

Step 3: Cover It Up

Take a shovel and block the end of the pipe like in the picture. Once you do that cover the tubes up with dirt. Stick the blower in the end of the tube, put some hot coals in the thing and then turn the blower on. (Caution do not pick up the coals, even if they look very cool.) Lots of sparks go flying when you turn it on.



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    8 Discussions


    Question 1 year ago on Step 3

    I want to make a BIG bowie knife - to use to split logs (with a mallet) - I'm thinking about 18" blade and tang - do you think this sort of forge would be big enough to handle it (without having localised hotspots?

    1 answer

    Answer 1 year ago

    If you don't have an access to a power hammer, you can effectively work on about 6" of material between reheats. Steel degrades when heated but not worked on. Also knives are not starter projects. Check out for knowledge and info.


    3 years ago

    From my experience with my forge build I think that the leaf blower is probably way more energy than you need, it'll burn up the coals faster than needed. Probably the simplest fix would be to pull the leaf blower out a bit so not all the air is pushing through.
    I cannot tell from the image, but it looks like you are using charcoal briquets. For a test that's probably not a problem, but I've heard that the binder in charcoal briquets can cause some issues with forging. lump charcoal (super easy DIY) is better, and from some of my sources one of the best forging materials.
    Also, it seems we are kindred spirits when it comes to making a forge, my forge instructable was also made of dirt, though I just used things I had around for all the not dirt bits.
    Best wishes on the knife, if you aren't familiar with Walter Sorrells youtube channel I highly recommended it as a good source for knife making info.

    5 replies

    Reply 3 years ago

    I used my version one forge to make a krambit with a wrench. It worked pretty well with the charcoal but I used a lot of it. Are there any cheap alternative besides propane. thanks for the help


    Reply 2 years ago

    Not to toot my own horn, but making charcoal can be dirt cheap
    Lump charcoal, which is just wood that has been turned into charcoal, can reach temperatures just below 6000 degrees Fahrenheit. If you can get a 55 gallon metal drum with a lid, you could feasibly make more than enough charcoal in one batch for making a knife.
    To extend the life of the charcoal you can reduce the amount of air going in, on my forge I considered using a hair dryer for the air supply after I saw how much fuel I was wasting with a shopvac blower.
    as for oil, from everything I've read, it really doesn't matter. There will likely be someone that comes along as says you must use vegy oil, another person will say you should use burnt motor oil because of the higher carbon content, and yet another person will tell you that you should use salt water or ice water.
    The whole point of quenching is to freeze the metal structure where it is, the amount of carbon in the oil that gets into the steel is miniscule, and you will likely already be working with a carbon steel and heating it with carbon fuel.
    I generally just use water, and swish what I'm quenching around in it to provide uniform hardening, my second most used quenching liquid is used motor oil from my own car, again swishing the piece around. the purpose of swishing is to reduce the leidenfrost effect.


    Reply 2 years ago

    I was running out of time while making my knife and turned up the blower to full power and it melted the tip off my knife.


    Reply 2 years ago

    And also what type of oil should I quench it in