What is the best way to bond together ifb?

D

Dr.O

Joined
Nov 13, 2008
Messages
69
I'm putting together my homemade heat treat oven, and have everything. I mixed up sairbond, and when id rub it on the joint the firebrick would suck the moisture out of the brick before I could stick it to the next one! Im talking half a second here. It's seemingly impossible to do the project this way.

Any tips? I also have satanite if that would be better, or should I look to the home depot for some premixed refractory?

What am I missing here?

Thanks for your replys!
 
I bought this at home depot

Black Stove and Fireplace Mortar
or refractory cement


It's black thick and sticky like tar

If it's not perfectly cured and hard, it puffs up when hot though.
 
I couldn't find the Rutland stuff at Home Depot (maybe because I'm in California), but I did find it at Tractor Supply. It's a seasonal item here.
 
I have used satanite to bond insulated bricks together and had to fight the same thing you did. I bet Rutland's will work better.
 
I had the same problem on my first HT oven build. Getting the bricks good and wet helps somewhat, but they take an age to dry (at least in the UK climate; you may have less of a problem).

I've not actually bothered with bonding them together on any of my more recent ovens.

With quality IFBs, the fit is very good and I'm too cack-handed to get accurate control over the joint thickness with a mortared joint. It just seemed easier to build with dry joints and make the frame out of angle-iron tight enough to hold it all together.

It actually works rather well.
 
Generally, you just have a dry fit. Use stainless wire pins to hold things together if needed. The shell should hold all together snugly. Some folks bind the bricks up with binding wire.
 
As Stacy says, if you need to, you can pin the bricks together with something like 3/32" welding rod.

My first attempt involved grinding a D-bit on a 3/32" TIG tungsten, drilling through the IFB and fitting pins made from 3/32" stainless welding rods. Then I found it also worked if the D-bit was made on the end of the welding rod.

Being unhardened, it will only last the one hole, but that is enough. They do not even need to be particularly accurate; it's a few seconds on the grinder and stop when it looks something like it should. With IFB, the lack of flutes does not seem to be a problem and I found I could just keep going. I assume the dust just gets packed into the voids in the IFB. My deepest holes through IFB so far are 22 1/2".

It's easiest to get the hole started with a 3/32" twist drill, just to establish the direction. Then use the D-bit, which keeps going in the same direction. With the D-bit on the end of the pin, it's just a case of break through and trim the pin to length both ends.

For anyone unfamiliar with D-bits, they are usually shopmade tools, used either as a sort of primitive gundrill or as a reamer. There is some information and a picture at
http://www.practicalmachinist.com/vb/general/d-bits-154906/
 
My only experience is making a small forge. The bricks were arch bricks if I remember correctly, so they didn't quite fit together exactly right. I coated the inside with cement, but didn't bother with mortar between the bricks as this was discouraged in the wip I followed. Out of curiosity, I have put my hand near the widest gap (probably 1/8" at most) and felt almost no heat escaping. My little forge is held together simply by wrapping in 1/4" hardware cloth, and with all-thread bored through 3 corners with washers (to distribute the force) and nylocks(sp).

I'm not sure how all of this translates to an oven, but my gut says that you shouldn't sweat it too much.
 
timgunn1962 said:
It just seemed easier to build with dry joints and make the frame out of angle-iron tight enough to hold it all together.

It actually works rather well.
Click to expand...

This is how I did my oven ....... I am amazed at how good it holds the heat in without mortar.
 
Thanks all! I looked at an even heat oven or two very closely to see the construction method, and all of the joints were a perfect 1/16" filled with gray mortar.

I'm going to go the angle iron welded route, but now I'm more curious than ever how they got those bricks together!
 
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