My IFB/fibre-blanket furnace build.

My next step is figuring out how to place the burner within the brick. It is only a mini burner, something smaller than most of you have ever seen. But it seems to work. The outside tube measures less than 0.410”

 

Like Jason said: 4 inches is a pretty good starting point for the exhaust hole, you can always resize it larger with a diamond disc in an angle grinder. It's also a good idea to radius the sharp corners of the hole to reduce the whooshing noise of the furnace a bit and eliminate hot spots from the corner geometry.

 

Yeah Unifrax is about 45 minutes north of me in Tonawanda, NY. I wouldn't want to work in any of those places.

 

I cut up some 1/8 stainless steel TIG rod (18” long) and skewered the fibre blanket on the bottom.



I put the torch on a 45° angle pointing down 5°. Then pipe clamped it all together.

 

Looks good.
I think you are going to have to pull the burner back into a tuyere area to keep the tip from overheating, depending on whether you are going to do just AL melts, or want to go with cast iron melts.

And the usual backyard caster's joke:
"Hey, you got the burner on the wrong side of the furnace. You know flames don't circulate clockwise !!!"

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Pat, the burners through just a show the angle. The IFB’s just got themselves a nice wool jacket.

Almost 70 feet of SS 0.035” Mig wire holding the fibre blanket in place.

 

The 10pcs. 1/8 stainless steel skewers go through the insulating blanket and are standing off on the metal plate. They are being held in place by the seven stainless steel hose clamps.

My earlier calculation is everything above the floor fibre blanket will be weighing about 70-80 pounds. Maybe tonight I’ll try to get a better mass.

 

He could hit those clamps with a tig spot weld and stop them from loosening up.

 

I may or may not be mortaring the top. The guys doing the install did showed me how they mortared them. It was super clean and fast.

On top of the two hose clamps around the lid IFB’s, I will also be toe clamping them with the two rings of stainless steel, A fender washer two 5/16 screws and a coupling (x10 pls.) in the Little V’s. This will add to/for lid lifting mechanisms. This Will be a secondary clamping force to prevent the brick from dropping in, unless the crack and fall in in pieces.

I’ve done a new calculation for the total weight above the floor fibre blanket and I am sitting around 110 pounds displaced over a 16 1/2 inch brick circle, 20 1/2” including the fibre blanket wrap and stainless steel future wrap.



Kelly, you have picked up on my only concern when I was designing this.

I question myself with,
- Would the fibre blanket condense/crush under the weight of the walls.
- Will the base brick, being held with just two hose clamps maintain a larger platform displacing wait on the fibre blanket uniformly.
-Will the fire blanket receive enough transferred heat to fatigue it’s rigidity.
- Will thermal expansion of the brick/hose clamps permanently stress elastic deformation of the hose clamps clamping force.
- Will there be enough subtle clamping force to hold the skewers enough.

I only took one precaution. I cut the stainless steel skewers to be a 1/4 below the top brick of the furnace. If I witness the skewers protruding past the top brick, I will know there is some type of compression of the fibre blanket is happening.



My back door fix is to weave a Web/trampoline of stainless steel wire underneath the base brick and above the fibre blanket attached to the barrel cart.

Yes, everything is being held in place by gravity or some type of mechanical clamping force.

 

Yes they are lower density. Just shy of 1.7 kg each x 30, with off cuts and dust collected I have counted up and weighed 9 kg. I’ve almost added 9 kg of fibre blanket above the base of fibre blanket, So that’s almost a wash.

The total weight of the lid should be under 18 kg. All assembled. I’m guessing but 50% of that we will be relieved by the lifting mechanism.

I also thought along the same lines as you, why not cut out the base of blanket and drop in 5ish fire bricks about 1.9”. I could orientate them so they pick up two parts of the base and wall. I do have 10 bricks to spare. I’m not ruling it out. It would create a good net pad.

You’re thinking along my solid second back door.

 

The furnace assembly is looking good.
Looks like you are getting close to test time.

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I got the Kelly curse nightmare sleeping last night. So today I did a complete tear down and rebuild. The floor now is supported by the offcuts of IFB’s. More pictures to come. Or do you guys prefer video???

 

Either one is good, just so long at I don't run out of popcorn.

Edit:
I have tried using IFB's on top of ceramic blanket,and it caused the IFB assembly to rock around and generally be unstable.
I have started using 1/4" thick strips of ceramic blanket under the bricks, just to give a little cushion between the brick and the steel base plate.

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No problem. Better now than later. Cheers. What are your thoughts on the double torch being 180° opposing? Or in your opinion does it really matter?

OK, get out your popcorn. I do zero editing.

 

I have operated twin oil burners at 180 degrees, and had I known what I know now, I would probably still be using that setup.
The commercial dual burners are at 180 degrees, when both burners are in the same plane.

Using an angle other than 180 degrees could cause one burner to impinge on the other, but probably the biggest consideration is getting a smooth and even burner all the way around, and thus the 180 degrees will do that.

A single burner will melt iron just fine though, and a single burner has much less combustion air piping to get in the way.

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