JAPOB Frustrations

[Chelonian]

I'm having some issues with my JAPOB forge. I built it about as closely as I could to the one Charles R. Stevens made. The "firepot" is the size of one red brick, the air inlet pipe has a 1 1/4" inner diameter, and I'm using bituminous coal. The problem I'm having is that if I make the fire even just above the top of the "firepot", the airflow becomes extremely restricted, and either I have to make the fire shallow again, or the whole forge goes out pretty fast. The blower I'm using is a Champion 400, so I doubt the problem is insufficient airflow.

The coal I use is mostly fines, but I was told that that isn't a problem. I have had some success heating up metal, but I feel like if the fire was deeper it would work a lot better.(?) If there are any details that I didn't mention, let me know.

Thanks!

[Glenn]

Try using 3/4 inch or 1 inch pipe for the air.

[Charles R. Stevens]

First slag sticks to brick like glue. Then JABOD mark 3 is a charcoal forge.                                                                                                             side blast coal forges are a bit different. 

 

 

[Chelonian]

Oh. What are the differences? Would I be able to make the required modifications to my current one, or would it be better to start over from scratch?

[Charles R. Stevens]

So the chart below is for side blast coal forges and the illustrations show a coal forge for. 1” tuyere. Not how the tuyer is 1” off the bottom of the bowl. This space if for slag to collect. 

Formcoal fines (dust) it is recommended you wet it and form a paste. You then as the past to the side of the working fire to coke. 

Now traditinal English side blasts use cinders and  fly ash for fill, but clay with a coating ash or a mix of only a third clay and 2 thirds sand with or with out ash work well. Many use sand as fill but as sand melts and forms silica slag but I find cheep clay cat litter or dri-sweep work well. 

I type slow, lol

Now with soft coal you can actually fill the whole pan with coal and use the green coal and an occasional sprinkle of water works as fire spread is limited. You can use brick, clay sand etc to fill in all but a box about 12” across and 8” or so deep. The box then can be filled with coal. Coal management is just a different than charcoal.  

[Chelonian]

Do I need a water cooled tuyere? I don't have a welder, so my fabricating skills are pretty limited. Are bottom-blast forges simpler to make, or harder?

Thanks!

[Glenn]

Bottom blast coal forges normally have a ash tube and ash dump below the fire to get rid of any ash build up. 

Side blast coal forges the ash builds up below the fire ball as does the clinker, and needs cleaned out when it interferes with the fire.

Both are simple to make.

[Charles R. Stevens]

You can treat the tuyere as a consumable. 

My personal feeling is sideblast forges are generally cheaper, easier and more versatile. Tho they are not usualy as portable.

[JHCC]

I agree with Charles about the cheapness, ease of building, and versatility of sideblasts. For a simple dirt- (or brick-)filled forge, the tuyere will be a consumable, but you can minimize this by using the heaviest pipe you can find. 

A water-cooled tuyere is a quantum step up from a simple pipe tuyere. If you find yourself with access to a welder and a supply of plate steel, definitely take advantage.