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Charles R. Stevens

Anatomy and a brief history of simple side blast forges

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I do not know if you came across my thread while you were doing you research but it has a lot of discussion on side blast forges. Unfortunately, most of the pictures have been lost but I re-posted my pictures and the plans on the second page.

I ended up building a side blast forge based on the plans Mark Aspery put out. It has been in use for several years now and I am very happy with it. I have a good friend who uses a bottom blast fire pot, which I use regularly. Both types have their strengths and weakness but I have come to prefer using the side blast more as I find it to be a more versatile forge.

You can find my thread here https://www.iforgeiron.com/topic/26716-side-blast-forge/

 

 

Forge-6.jpg

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Thanks for linking to your thread, I actually have it saved to favorites, as it provided information on Mark Aspery's design and your forge itself is just beautiful. Especially the simply elegant side draft hood. A reminder for those not in the know and just starting out, the tuyer is way to big for a charcoal forge, but is a great design for a general purpose coal forge. 

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As Mr. Stevens has mentioned, I have built two side blast forges. There were four documented side-blast forges during the U.S. War Between the States [WBTS] used mid-1800s.  All four forges were open box structure with the largest one used by the navy which was an open approximately 2ft by 3ft metal box.  During Sherman's famous march to the sea, his blacksmiths simply stuck the nozzle of a bellows through a hole in the side of whatever wooden box was on hand, and covered the bottom of the wood box with a layer of dirt.  European side-blast forges that I have seen pictures of, also were open hearths without tuyers, just a box with a nozzle sticking into one side.  The sides of the fireplaces were to just keep the fuel from falling onto the ground.  

Comparing the two side-blast forges that I have built, the one forge has about two feet of 2-inch copper pipe running from the fireback to the bellows, while the other has about a foot or less of schedule 40 black pipe.  While the two foot long copper pipe works wonderfully well, the short steel pipe heats up and I have to wrap a wet cloth around it to prevent heat transfer to the wooden bellows.  Someone posted a water tuyer on the Internet that prevents the heat transfer.  So to make the forge with the iron pipe work properly, I will either have to lengthen the air pipe, and possibly insert a copper pipe, .... or will have to build and install a water tuyer. 

Below are some sample side-blast forges, from the WBTS.

So in summary, all the old side-blast forges that I have seen or built are basically wood or metal boxes with an air pipe/nozzle poking through the side of the box. And the main consideration, in my humble opinion, is whether there is heat transfer to the device providing the air supply. 

 

US Army Portable Forge diagrams screen sized image.jpg

Traveling Forge built by David Einhorn author of the book Civil War Blacksmithing cropped.jpg

 

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These type of forges look interesting and I was doodling a variation of a trench style one.  Do you all mind looking over it and pointing out any glaring issues that I might be missing?  The basic idea is to have the front and back of the trench open in case I need to heat a long piece of material.  The tuyer would be a capped piece of black pipe with either holes drilled or a slit cut into it.

File Nov 09, 1 40 04 PM_preview.jpeg

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Interesting combination of the Tim Lively washtub and the JABOD. If you try this, I would recommend not capping the back end of the tuyere, but inserting a plunger that can be adjusted to regulate how much of the length actually delivers a blast.

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The glaring issue is that this would be for forging long scrawls in one go or heattreating long knives and such. As even swords are forged 6" at a time (power hammers not withstanding) other wise the basic consept is sound. This is the basic idea behind the Japanese sword forges (again you only need a 3' long forge to heat treat the blade).  

JHCC's suggestion allows you to shorten your fire for forging size to sword heat treat size and in between. I would use a piece of 1" schedual 80 for say a 8" forge with either 3x3/4" or 5x 1/2 holes. This is because schedual 80 is pretty dang close to the listed ID. So a 1" steel rod will just about close it off. 3/4" schedual 40'is acualy PDC to 7/8"

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On 10/6/2017 at 9:58 AM, kubiack said:

 

Forge-6.jpg

I see that much air blowing the flame into the chimney means there's  an equal amount of  air flow into the shop.  Where is it coming from?

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