Chimney Type for Forge - Opinions

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Augus7us, Nov 18, 2018.

  1. Augus7us

    Augus7us

    694
    Oct 9, 2014
    For those of you that have experience with indoor forges and their chimneys, I'd like to get your opinion on what type I should install.

    In my eyes it comes down to either a side draft or overhead hood style chimney. I've always thought the overhead did a better job, as its directly over the fire bowl. However in researching this it seams most use the side draft.

    This will be for my coal forge. I do plan on building a 3'x4' brick "table" for my fire bowl and this would allow me space to set a smaller gas forge on the table part, under a hood to evacuate some of the hot air. I thought this might be an advantage for the overhead style. What do you all think?

    -Clint
     
  2. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Both work good, but the side draft is more popular because it allows full access to the fire pan area ( no hood in the way).

    Also, make sure your stove piping and exhaust piping is up to code. You need triple wall where it goes through the ceiling, roof, or walls. In the shop it can be single wal, but needs to enter the higher rated pipe at the ceiling/wall.
     
  3. Fred.Rowe

    Fred.Rowe Dealer / Materials Provider Dealer / Materials Provider

    May 2, 2004
    I operated a large side draft coke forge for 4 years and turned out quite a few blades. A side draft table can be smaller in area because, with no overhead hood, you can look down on the fire and not from the side. Whatever you build; having a great chimney will make for a great forge, whatever the configuration. The top opening must be large enough so as to not, creosote over, blocking the draft. The top of the chimney must be above the top of the roof peak by several feet. if you want it to draw. All exterior pipe should be insulated or triple wall. We built our own using chimney pipe of two sizes, with 1" KaoWool insulation in between. A straight, hot, chimney draws best. Use the best coke or hard coal you can get your hands on. A hot fire will eat a large billet of steel in about 47 seconds, or it seems like that W. :)
    Best of luck, Fred
     
  4. Tom Lewis

    Tom Lewis

    Feb 24, 2000
    I no longer use coal, but when I did I found out that the taller the chimney, the better it draws the smoke out.
     
  5. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    That is quite true. The upward draft of the tall chimney draws more smoke and heat up due to the venturi effect.
     

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