timber frame JABOD

[robie1373]

I have really enjoyed digging through the posts on this forum for design inspiration and cold, hard facts. Such as can be found

There is so much information here. Unfortunately, I'm a simple dude who's brain can only hold so much. I have made a drawing of the firepot aspect of a solid fuel forge based on information from Mr. Stevens' and Glenn's stickies threads. Thank you gents for those awesome resources. Because there is so much information and there are so many ways to skin the rat and YMMV, I had to simplify a bit in hopes of successfully completing my build.

Here is the diagram that distill what I understand from Glenn's 'Forges and Fires' thread and Mr. Stevens' several JABOD threads and comments. 

Assumption 1: I'll be working steel < 1" by hand without a striker or power hammer. I believe this means I don't need to worry about heating up more than 4 or so inches of steel at a time.

Assumption 2: I want the flexibility of working with different solid fuels. I use bituminous coal in the guild forge today. I like the idea of burning coke. I am curious about charcoal and even plain wood. I think the JABOD design will give me this flexibility by reshaping the firebox and/or building up the top of the table with bricks if needed.

Assumption 3: I'm going to rebuild this a few times as I learn. Just a fact I guess. This seems to be the way others around here work too.

 

The table of the JABOD is only interesting from a woodworking viewpoint. 

It's been hot here, so I'm making less progress on that heavy joinery than I had hoped. Slow and steady beats the hospital.

[JHCC]

Forge looks basically good. Your pay-attention-try-it-out-modify-as-needed attitude is even better.

[robie1373]

I finished the joinery on the base of the JABOD table tonight. The 2x8s simulate the box for dirt. The other picture illustrates the height of the finished box. I'll tongue and groove some 2x8s for the bottom of the box. The sides of the box are going to have tusk tenons holding it together. 

[Charles R. Stevens]

Fancy woodwork 

[robie1373]

While totally unnecessary for function, I find the SAF (Spousal Acceptance Factor) goes up when I put some effort into making things purty.

[Charles R. Stevens]

This is true...

 

[ThomasPowers]

I would suggest not using pressure treated lumber for the upper rim as that's the area most likely to have contact with hot metal.

[rockstar.esq]

As a general comment, I'm not sure the fire brick at the bottom is strictly necessary or beneficial.  Sand/dirt is an excellent insulator and it's easier to pluck clinker out of soft stuff. One of the things I really love about the side blast is how the clinker flows beneath the fire where it collects out of the way.  It'll eventually get large enough to interfere but since it sets up in a layer, it's prone to coming out whole which saves a lot of struggle.

The other nice thing about using sand or ash is that you can offload the weight into buckets for easier transportation.

[Charles R. Stevens]

With loose fill I like to use brick in the floor and as a wall on the tuyere side, primarily to prevent one from getting over enthusiastic in digging out your fire bowl Wen building a new fire. They aren’t nessisary, but nice. 

I also don’t like sand, as it melts into Slag, I prefer cheep dry cat litter/drysweep. 

[robie1373]

Basic construction is complete. In case anyone is curious, I diceded to go with sliding dovetails to attach the sides because the through tenons and wedges started to seem awful busy and ungainly. This is plenty strong, looks nice as dovetails usually do, and keeps the lines cleaner. There are fewer sticky-out things to bump into or catch tong handles on, or crack my skull on while picking something up off the floor.

I left two of the sides long so I can run a bar between them for a tool rack. 

I think my tuyere might be too long...

That's better.

3 hours ago, ThomasPowers said:

I would suggest not using pressure treated lumber for the upper rim as that's the area most likely to have contact with hot metal.

That's a good point. Unfortunately, pressure treated is what I have that I'm willing to throw at this project. As a mitigation, I'll probably keep some bricks in the box for fire shaping. I'll make sure to store them proud of the edges in locations that seem to be getting burned. 

Additionally, I'll be using this outside in well ventilated spaces. That's probably an obvious statement, but worth noting. Truthfully, though I am more concerned by what I breath in on my daily driving around the beltway than this. Not a reason to ignore good advice or invite trouble, but more a sense of proportion.

1 hour ago, Charles R. Stevens said:

also don’t like sand, as it melts into Slag, I prefer cheep dry cat litter/drysweep. 

Thanks for mentioning this. I was hoping to ask you if you still preferred the litter. It sounds like you do.

I have a few ideas where I can sneak a bucket or two of dirt out of the public areas (actually high-tension power line right-of-way) in my neighborhood, but at the end of the day, I think a bucket or two of cut-rate kitty litter might be a small price to pay to avoid Undue Attention.

[Charles R. Stevens]

Dirt works just fine, just sand causes isues. As ash collects it all gets better.  I still just use the clayed soil  under my feet for simi permanent forges, but catliter beats sand for portibles. 

[rockstar.esq]

I guess I never noticed sand turning into slag but it makes sense.  It might be stuck to the clinker.  I suppose kitty litter would be lighter than sand which would be a nice trade.  Wouldn't the kitty litter vitrify in the fire?

[Charles R. Stevens]

Yes sir it dose, i fact it forms little clumps, but generaly when you fish out clinker or build a new fire they break up. The key is they melt at much higher temp than sand, and the small amount stuck to the clinker is replaced buy the ash, eventually enough ash builds up to stop that. Eventually ash builds up in sand and deals with the slag isue as well, but in the mean time you have to deal with more slag. 

 

The down side is you have to keep it dry

 

[robie1373]

All finished and set up in the far corner of a patio. 

I started a fire with some scraps of oak from the woodpile. My fire was pretty shallow, but once I got some nice coals in the bottom I had 1/2 square bar at forging temp. I had just enough time to draw out a point and taper before it got too dark to see what I was doing.