Charles R. Stevens

Just a box of dirt, or a simple side blast forge

83 posts in this topic

7 minutes ago, Charles R. Stevens said:

First 3 are the forge in question, last two are the smaller MKI forge.

That's great; many thanks.

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Charles, can you explain the MKI a little?

It looks like a bowl inside a trough. Is the air intake at the top of the photos?

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The MKI forge was a test bed. The air supply is a double action bed inflator. Basically a small box bellows. The air out let is the size of the outside of a peice of 1/2 pipe, so the tuyere is 1/2". I started with a bowl 5" deap and 6" across. Their is a back wall of mud, that makes it easy to bank coals against. The tuyere comes out so the bottom is 1" off the floor. As the air supply is limited the hot spot was only 2" above the tuyere, so I had to dig trenches and cut the sides of the box to run long stock threw the middle.  It worked fine for shoeing stock (5/16x3/4") maxing out at about 1" it's small size, and manual air supply made it very effecent. 

The tuyere comes in on the mud wall side and is flush with the wall.  

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Thanks for the info on this build, Charles! I'd seen some wood-frame forges, but have been trying to gather some metal to
build a forge body. I was doing some last-minute searching for designs, saw this post, and decided to go your route -- so, your post
saved me a good bit of time, money, and effort.

Before I get to drilling a hole for the pipe and filling the forge with material, I
had a couple questions to make sure I'm setting it up for the best heat.

1. You mentioned yours is 7.5" deep. Since you're using 1x8" boards, I'm guessing
the 7.5" is from the wooden bottom to the top of the boards. So, since you
mentioned having a 1.5-2" brick floor beneath the clay/sand, is your fire hole only
about 5.5-6" inches deep, including the 1" space below the tuyere?

2. For correct fire ball placement at the of the clay, the charcoal above the clay top should be 2-3" high (or more) for best fire ball
placement at the top level?

3. Also, for general purpose forging like you pictured in the post, how wide across is the
hole at the bottom and top where it flares out? 

4. You mentioned the clay will harden some in the fire hole -- do you just pull the
harder pieces out and reshape the pot as needed?

5. Just to verify the layout. It's a 1.5-2" brick floor topped with clay/sand/etc.
Then, there's a 1" space below the tuyere and charcoal piled up to a few inches
above the surface? ** I'm attaching a sketch of how I'm thinking the layout should look, with each
rectangle being 1" tall. **

Many, many thanks again for the inspiration for the build and for any info on the questions.

- Scott


 

Side-Blast-Forge-Drawing02.jpg

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Pretty close, the brick floor is for sand or ash fill, as we tend to get to agresive and dig down to close to the wood... 

Smoke from under the fort is bad juju. 

The bowl is in deed only 5 1/2" deap, so the top of the tyere is only 3 1/2 l below the table. This puts the center of the fire at table top hight with a mound of fuel covering the work. 

T bowl is about 2" at the bottom and 6" at the top, as you only get a 6" fire ball with a single outlet tyere. Anything bigger is a waste of fuel.

my soil is so clay rich it vitrifies (turns to fired poetry) around the fire, this is ok as it holds its shape as long as you don't introduce rocks from your fire pit, burn up hiden nailes in your scrap or use coal. Slag sticks to fired clay like glue.

 

image.jpeg

The wind was howling, so I needed a wind break, spaced the two lower bricks so I could run long stock threw

She is going to need a major repair as I used coal in her and the slag stuck to the bowl, if you use coal, I recomend sourcing sand.... 

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I sure do appreciate you posting all this, Mr. Stevens.  A friend of mine needs a new forge, and I've been talking up a wooden one when I came upon your thread.  It's been a great help.   Thanks.  

My great grandfather used a wooden forge.   We have no pictures of it, unfortunately.  That would have been around 1900 or so.   

Joel Sanderson 

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During Sherman's March to the see, the smiths ditched the portable forges and only took the bellows, improvising with packing cases, small timber (think log cabin) and sod. 

Remember this isn't a blue print, it's inspiration. I've been eyeballing 32" pots at the garden center... 

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Thanks for the reply, Charles! I definitely appreciate the clarification. I planned and drew everything out twice using the general measurements you gave, got it all cut and put together... and realized I forgot to factor-in the thickness of my bottom boards (mine are mounted in the interior of the frame instead of the very bottom like yours shows). Amateur carpenter lesson learned. Haha

So, instead of bricks on the bottom now, I'll have some thick tiles as a digging barrier. It'll work out great, thankfully, though. Now, I'll just get some clay or sand, put in my blower, and start forging. Also, mine will be outside, so I'll be building a hinged lid to keep the interior dry. I'll be sure to post a picture once I get it all finished.

Thanks again for the great inspiration!

 

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If the bottom gets to hot, just bring up the tyere, 2/4" or so won't make a difference

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31 minutes ago, Charles R. Stevens said:

If the bottom gets to hot, just bring up the tyere, 2/4" or so won't make a difference

Good thinking. I do have enough space for a good layer of clay between the tiles and fire pot, but I'll keep an eye on it and move the tuyere if needed.

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Or you could just slap a rim around the top to increase the height.

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5 minutes ago, JHCC said:

Or you could just slap a rim around the top to increase the height.

True! I think I didn't even think of that simple solution out of frustration. Hah. I used 2x12s for the sides, so I had plenty of room already... had I added up the space measurements correctly (math... ugh). And I have the top at a perfect standing height currently. So, before adding more material to the forge top, I'll give it a go like it ended up.

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If you like the current height, add a rim and trim the legs.

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16 minutes ago, JHCC said:

If you like the current height, add a rim and trim the legs.

And with yet another good suggestion, it seems the common sense portion of my brain must've stopped working. Thanks for the "duh" inspiration. 

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Keep going Scott, and remember to show us some pictures.

I am making plans for a future forge like this. I would love to see how yours turns out.  

Charles, you have mentioned a couple of times the tuyer being 1" or so off the bottom of the fire pot. I have seen others say the same thing so I assume this is based on lots of experience. 

Can you explain why this is? I understand why you don't want it lower, but why not any higher? I'm just looking at understanding not improving anything.

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Fuel effency and tyere temp. 1" allows enugh room for a substantial puddle of slag to form when using coal. So not stricktly nessisary for charcoal. Anything deeper and to much fuel is waisted siting below the air In let, and having the tyere not at (or near) the bottom subjects it to more heat.  

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That makes sense.

I have coal... So slag is a given... That means having sand or ash in the bottom to protect the bottom... In that case should I build in a 1/2" for this? A little sand bed on top of the bricks?

Have the tuyer 1.5" off the brick?

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Yep, a little sand or ash, say 1/4" to keep the slag from sticking to the   bricks. 

You might find that a floor flange screwed onto the end of your tyere pipe keeps slag from getting under it and extends the life of the tyere with sand or ash fill. 

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I'll have to keep that in mind. Thank you

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Right now I've got clinker-rich bituminous(I think?) coal. It comes mostly in fines than in chunks. It clinkers up bad in just a few heats of 1" thick bar. I've been attracted to the idea of a side-blast forge. Is this practical with my fines? I would think that it would coke up just fine and I'd just keep feeding in the green coal.

I think the sideblast concept will help me work longer before having to clean out clinker. But it seems to me that cleaning out clinker would be more difficult than in my bottom blast setup.

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First, clinker likes clay, so use sand or ash to fill your side blast. 

Cut the air a Kinney or two, lift the top of the fire with your shovel, and block the clinker with your rake.. Push the Coke back in with the rake, replace the top of the fire and get after it. 

Bullet grates can be a godsend with bottom blasts.  

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Firstly, sorry for reviving an older thread, but the build I had in mind is nearly identical to this one. Mr. Stevens, how is the air mattress pump working for you? I have one that I was planning to use but I've read that they are underpowered for a forge and typically don't last long since it's meant to run only long enough to inflate a mattress. But experience trumps armchair knowledge. Also, Happy Birthday.

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