Making a big forge smaller/more efficient.

[Danjmath]

I bought all the things I needed to build a better forge than the cobbled together fire-brick/Frosty T-burner I started with, but while looking for used #100 propane tank, I found someone selling a barley used custom forge together will a full #100 tank. It was only $100 more than a new full tank so I pulled the trigger. Problem is, its much larger than I was looking for/need.

The dimensions are 16" long, 6" inner diameter/ Its forced air, with the burner right in the middle, and 3" of refractory all around it.

So far I have done one long (20" total length) knife where I actually was glad of the length, but usually its way overkill.

It actually runs pretty efficient once it gets up to heat, I go from 4-10 PSI depending on what I'm doing.

Is there anything I could do to improve the efficiency? There were 2 things I was going to try.

1. Add a coat of ITC-100 or something similar.

2. Build a removeble 'plug' to put in the back 6 inches. I have Kaowool and mizzou refractory I could use to do this.

Would either/both of those increase the efficiency?

Then again, there is also option 3: Build the forge I was originally planning on, and save this monster for the rare occasions when I need it, but I would rather put the limited time I have into working metal, and my shop is too small, and I don't think I could put anything else in it.

Thoughts/comments are appreciated.

 

 

[ThomasPowers]

What type of refractory is that 3"?

[Danjmath]

Not sure, works well though, I've made Damascus billets in it, and the outside is still cool.

[timgunn1962]

I'd roll a kaowool plug to put in the back as you suggest. That will reduce both the volume and the open area (no back port, though you can leave a gap in the middle of the plug if you need a pass-through), then I'd roll one or two layers of kaowool inside the front end to reduce the open area to little more than is needed for workpiece access. That will reduce the heat loss considerably and let you turn down the air and fuel. There will be a limit to what you can do before the mixture speed through the burner drops below the flame speed and you get the flame burning back into the burner tube, so watch for this. You also want the open area to be at least 5 times the burner area, preferably 7 times. If you just have a front opening and make it 2 1/2 times the burner ID, you'll have 6 1/4 times the area. I'd probably just use kaowool initially, use it outdoors and wear a mask, until I had some idea of whether it was giving the desired result. Then coat the kaowool and immobilize the fibres for longer-term use. 

I'd try very hard not to do anything irreversible unless/until it does everything it needs to do.

[FlatLiner]

I saw that forge on KSL. If worse comes to worse sell it and build what you want or maybe knock out the refactory and rebuild it with kaowool  with a 1/2" layer of refactory and a moveable plug.

[Danjmath]

I may try a lined Kaowool plug, see if I can make a removable one.

Thanks everyone!

[Irondragon Forge ClayWorks]

Instead of ITC-100, I would use Plistix or metrikote.

22 hours ago, timgunn1962 said:

try very hard not to do anything irreversible

Good advice.

[Danjmath]

25 minutes ago, Irondragon Forge & Clay said:

Instead of ITC-100, I would use Plistix or metrikote.

Good advice.

I actually have Plistix, and this is a bit off topic, but where is the best place to get more. Hard Knock Forge, where I got my original bag from, seems to have been out of stock for a while.

[Glenn]

Gas Forge Refractories and Supplies  are sold in the IForgeIron store.