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Thread: Two-brick mini forge

  1. #1

    Two-brick mini forge

    The topic of toolmaking came up on the musical instruments forum, and I mentioned the "two brick forge" I had made a while ago. John Jordan asked for pictures and details, so here they are:

    The forge was made from two soft fire bricks (the kind used to line ceramic kilns), some angle stock, 1/4" rod stock and some nuts and washers from Home Depot. I sawed the bricks in half with a ryoba to make four 4 1/2" square pieces, and drilled a 2 1/2" diameter hole in the center of each of the halves with a hole saw. If you do it that way, save the "plugs" that wind up in the hole saw - they come in handy.

    The way the frame was made is obvious from the pictures. I used rod instead of all-thread because it came out cheaper that way, and you only really have to thread about an inch on each end.

    I painted the inside of the chamber, all the joints, and any cracks with refractory cement. Total cost was somewhere between $30 and $50 (don't remember - it was a while ago...).

    Drilled a hole in the front section for the torch, and cut one of the "plugs" in half to partially block up the back. You could drill another hole further back for another torch if you need to, but I found that using the TS-8000 torch head with MAP gas gets it plenty hot for hardening blades. Other guys have built similar designs and used propane as the fuel.

    The forge takes about a minute or two to heat up, and then it's good to go for hardening. I've never used it for "forging" blades, only to harden things I'd already made. But I think it would get hard enough for forging as well, at least for the small stuff that would fit into it.

    Unfortunately, I didn't take any "in progress" pics, but here's the finished forge:


    And with the torch inserted:

    In action:


    And the first thing I hardened in it, a kiridashi made from an old file:


    This knife was really useful in my last instrument build. The really nice thing about this little forge is that I can use it indoors all year round - it makes no more fumes than the gas stove in my kitchen.
    Last edited by Mike Recchione; 03-14-2017 at 3:39 AM.

  2. #2
    Join Date
    Feb 2008
    E TN, near Knoxville
    Thank you Mike. I like the way you hold everything together with angle iron and all-thread. That's what my potter friend uses when he builds his big kilns. (He had a 2" natural gas pipe run nearly a mile to his studio!)

    BTW, it looks like you have two identical photos but one is captioned "with the torch inserted". I assume that was supposed to be a different photo.


  3. #3
    Thanks, John - I edited the post to fix the duplicate picture. The right one should be there now.

    By the way - I didn't use all-thread. I used plain rod, and threaded the last inch or so. (It was cheaper than all-thread, and I was trying to see how cheap I could make this come in at.). Also - I avoided galvanized for this because of the possibility of zinc fumes, but I have to say that the rods and outside of the forge stay very cool - this is very well insulated. I probably could have saved another couple of bucks using galvanized nuts and washers. But better safe than sorry, I guess.

  4. #4
    Join Date
    Jan 2015
    New Hampshire, USA
    Thanks for sharing this Mike. Looks like you are all set to make those hardened scrapers.

  5. #5
    Join Date
    Feb 2008
    E TN, near Knoxville
    Thanks. I can see the rods better now with a better screen. I have a lot of all-thread on hand (we have a fantastic metal salvage place here) and a shed full of steel stock. This looks should be easy to build and cost me nothing but the gas.

    I want to use it for hardening turning tools. For one thing, I keep a box of old mostly cheep turning tools to give away and the file test indicated some were not properly hardened or just hardened a bit on the tip. It seems like this would give more consistent results than just heating with the flame from a torch.


  6. #6
    I really like that. I will have to build one of these.

    Where did you get your soft fire brick?

    You might be able to pitch a little lump of charcoal inside it to help reduce problems with decarb - which would then maybe let you do stuff like soak times longer than a several seconds.
    Last edited by John C Cox; 03-16-2017 at 5:00 PM.

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