Update: the adobe has been working well, but the initial layer was too thin to be sufficiently durable. It chipped out around the tuyere, which — being itself much too thin — burned back a couple of inches. 

So, I broke out the top layer, dug out about half the full, made up some new adobe (about 2:1 sand-to-clay), and rebuilt. The new tuyere is black iron pipe (3/4” schedule 80, I think) and is completely encased in adobe. The bowl is about 10” x 11” x 5” deep, and the center of the tuyere is about 2” from the bottom of the bowl. 

I also packed some adobe around the inlet end of the tuyere (inside the socket where the blower hose plugs in) to keep air from leaking out elsewhere. 

(N.B: what looks like a crack around the inside of the socket is just the impression left by the end of the hose, when I pushed it in to make sure it would still fit.)

What were you using for a tuyere? I have had good luck with 3/4" schedual 40 flash with the clay/Adobe bank. If you go to schedual 80 you have the option of going up to 1"pipe as it is much closer to the nominal ID. For this who haven't messed with pipe,3/4"  schedual 40 is about 7/8 I'd, wile schedual 80 is just a hair over 3/4". As the historical record showed charcol forge there's of 1/2-1" and my experiments show that 5/8 and 7/8 I'd work (as the larger tuyere makes a larger fire ball I prefer it, but I have successfully forget shoes in the smaller forge) 1/2-1" schedual 80 should work fine. 

If you keep having problems you might try a flore flange to keep the slag from getting under the tuyere and eroding the wall.

35 minutes ago, Charles R. Stevens said:

What were you using for a tuyere?

Some piece of random scrap with 1/32” walls. Not surprised it burned up. 

Checking your info against the new pipe, I think I’ve got schedule 80: the ID is about 3/4”, and the OD is just over an inch. I’ve updated the info above. 

35 minutes ago, Charles R. Stevens said:

If you keep having problems you might try a flore flange to keep the slag from getting under the tuyere and eroding the wall.

Oddly enough, the problem I was having with clinker was that it was collecting above the tuyere. We’ll see what it does on this version. 

Schedual 40 and 80 black pipe will have the same OD, I have a piece of stock 2-1/4" I'd with a 3/4" I'd stuff. The oil feild has some wild stuff, lol. I only use the schedual 40 for my experiments, lol.

And here we are after a rather vigorous session yesterday. As before, a crust of clinker adhered above the tuyere. The stuff that accumulated below pulled out fairly easily. 

EPILOGUE

After over a year of yeoman service, the JABOD has been retired and disassembled. It had a good life, and it taught me a lot. I will be forever grateful.

While it is no longer in our midst, its fill and air inlet live on in my new side-blast, which is documented here:

 

Its always sad to say good by to a dear freind. As the saying goes when the student is ready the teacher will appear..

 

It must be time for a new teacher of sorts..

I’ve looked in quite a few different posts on jabod forges but I’m confused on something. And if I’m just missing where it is written, I’m sorry for asking again but how does a jabod work. Because I see that the airflow comes out from the bottom of the fire pot but is there an ash dump?

No, no ash dump. When clinker forms, you hook it out of the fire with a poker. Any ash stays in the forge to become part of the fill.

How would using charcoal compare with coke? Would that fix the clinker problem but still be able to be useful?

 

Mostly, but not entirely. In a JABOD, some fraction of the clinker forms from the dirt fill, so you won’t eliminate it entirely, especially if you’re running a very hot fire. 

With charcoal and long term use the cinder, soot and ash  will displace some of the dirt.  

 

The design of a Japanese forge takes this into account.  The tuyere is slightly above the birds nest so is left to be.