My forge is cold

[rdennett]

I used an old wooden planter box to make a JABOD forge last spring and rebuilt it recently after it sagged and the bottom boards fell out.  The tuyere pipe is 1” black pipe connected to a hair dryer.  The end is about 2” below the top of the space for the fuel and sis dug out about 2-3” below that.

in the spring, I could get welding heat no problem using TSC rice coal, but since it kept turning into a tar ball and blocking the air supply (I was raking it out about every five heats), I decided to switch to using some coke I have.

Getting it lit is not an issue, but it seems to burn awfully cold and it’s really difficult to heat up metal. Coals above the air inlet more than two inches have about the intensity of a small camp fire even with the air on full blast.

This afternoon, I lit some lump charcoal and wood scraps to see it was getting enough air.  The coals were getting blown out as they burned down, but I certainly wasn’t getting the fires xx Xxxx that I would expect.

Any ideas here?  Too little fuel?  Too much air?  I can’t seem to get a consistent fire at all.  Last weekend, I went from waiting 5 or more minutes for a dull red to pulling out a sparkler after a couple of minutes.

 

Thanks,

Rob

 

 

Edited December 10, 2020 by Mod30
Language

[pnut]

A 3/4 sch 40 pipe might work better. I was using a one inch pipe in the first iteration of my jabod and had the same problem. That's a lot of room under the tuyere also. I have my tuyere about an inch above the floor of the trench and sitting on the bottom of the brick firepot in the MARKIII type I use now. 

Charles might be along with some advice soon too. 

Pnut

 

[Frazer]

I was looking at your build from previous posts, it sounds like you may have too much air and, like you said, are blowing out your fire rather than feeding it.

If your air source is the same, (are you still using a hairdryer?) it's possible after rebuilding the JABOD, the shape of your firepot isn't the same or there is some other variable (anthracite vs coke) that doesn't play nice with lot's of air. 

I would start with less air and go from there.

I'd think this would give you more trouble while lighting it up rather than once it's lit, but maybe the center of your fireball (where you're putting your steel) is relatively cool due to the excess air and only the surrounding area further from the tuyere is really burning properly? Not sure about that theory, just my 2c

[pnut]

Too much air will definitely cool a fire. It's been over a year since I've burned anything other than charcoal in my jabod so I kinda forgot that it's heavy enough that it won't  get blown out of the firepot if the air going to it is harder than a light breeze. :-)

Pnut

[Glenn]

Distance between the bottom the the air pipe and the floor of the box is insulation so you do not set the box on fire.  Take into consideration that there is some depth to the ball of fire at the end of the pipe.  The secret is the amount of coals and fuel over the level of the air pipe. You should adjust the size of the fire to the work at hand, small stock takes a smaller fire and larger stock takes a larger fire.

The fuel does not make the fire hot, air makes the fire hot.  Way too much air and not enough fuel will keep the fire from getting hot, or even blow the fire out.

Start over and check the air flow path for any obstructions.  Then build a small fire using sticks or kindling and adjust the air so the fire burns well.  Adding more fuel a little bit at a time, until you arrive at a nice bed of embers, and a nice size fire ball.  Adjust the air as needed to create the fire ball you need.