Recommendation? Cutting (Halving) Insulating Fire Brick

J

joedhiggins

Joined
May 31, 2016
Messages
485
Howdy all,

I decided to build a newer bigger propane forge and use insulating fire brick for the inner liner as ceramic wools tend to decompose on me a bit more quickly than I would prefer.

To cut down on the size, weight, and expense of the forge, I am doing an outer lining of ceramic wool. The design I made called for half thickness fire brick, I know these are purchasable, but not locally. So I picked up the full 2.5' thick bricks.

I want to turn these into ~1.25" thick bricks. I am wondering what folks recommend as the best way of cutting them such that they don't crack on me.

I was thinking a hand saw and jig (like a hand miter box) might work decently. I am a bit nervous to try a cut on the table saw (but if this method works I guess I could try). I have a band saw, but am similarly nervous, and after my recent move, the wheels have been knocked out of alignment and the blade wanders a bit.

Second related question, I want to cut a rabbit into the edge of a hard 3000f firebrick (this step is not absolutely necessary, but will add an additional mechanical lock to the lining). My thoughts are to use a diamond blade on an oscillating multi tool or angle grinder.

Would love to hear thoughts or suggestions, as fire brick is decently expensive and I would rather not go through several re linings worth just to figure out a process. Thanks!

Joe
 
I've usually cut them with a hacksaw, but I don't see any reason you couldn't use a woodworking handsaw provided it isn't one you care too much about.
I'm sure it'd work, but I wouldn't run one over my table saw. But that's due to the mess in the shop as much as anything
 
Hacksaw seems like a good idea, is it tough to keep the cut straight? the reason I was thinking about using a job box saw or similar was the extra blade width seems easier to keep from wandering.
 
Are you not coating your wool? That is not good. AlsoI am not sure that hard bricks are ideal for the walls of a kiln, but if you plan to use them, buy the "slip" bricks that are half thickness. I use one in the closed end of my 24 inch Paragon to shield the tips of my blades from the blazing coils.
 
Last edited:
Different IFBs are different to cut, so it is important to understand that one person's experience may not apply to your situation.

I have used 3 different types, all 2300 degF-rated, which I think of as "sandy", "bubbly" and "chalky". They cut *very* differently.

I have used a backsaw on all 3 types, but only for a maximum 3" Depth Of Cut. A toolbox saw or similar is probably going to be needed for a 4 1/2" DOC. A hacksaw is fine if you can cut straight enough and have a deep enough frame.

The "chalky" are by far the easiest to cut, with the "sandy" being a bit of a pain and the "bubbly" being downright awkward. The "chalky" ones cut with a handsaw almost like Balsa and don't seem to shorten the life of the saw very much. The "sandy" ones will cut with a handsaw and you'll get a good number of cuts, though the saw will be useless for anything else. I cut the first 2 of my "bubbly" IFBs with the backsaw before it no longer had any set to the teeth, which were severely worn on the tips too. I then used a 14" industrial hacksaw blade to cut the rest of the bricks for the HT oven I was building and that just about lasted to the end of the build.

I now use a cheap diamond tile saw for cutting and a router for grooving IFBs to make the HT ovens. The cheapest TCT router cutters seem to last remarkably well on even the "bubbly" IFB.

I think a table saw would be very effective. On the "chalky" ones, I'd just go for it (though I'd certainly not use my best blade). For the others, a table saw would probably still be my choice, but I'd use a cheap TCT blade dedicated to cutting nasty stuff. I don't think the pitch matters much.
 
I have an old bandsaw I use for cutting them. But it's the soft fire brick.
 
The only ones I have experience with are 3000 degree kiln bricks. They are so soft you could cut them with pretty well anything
 
Will definitely wear a respirator. and maybe wet it down. Gonna try one by hand and see how cleanly it cuts. And if it breaks.
 
Lucky me, I have a Masons wetsaw. It wont cut thru a single pass. I have to turn the brick over. Its a treat. If feeling fussy, one can easily make lapped or T&G joints too !
Anyway, most any hand or powertools will work. But dry, quite a mess dusty and the blade is pretty much exclusive to brick cutting thereafter.
 
I just cut some soft firebrick the other day on a table saw with a worn out carbide blade. Worked really well!
 
I normally use a hacksaw, though I've also used a wood panel saw (for 2300 soft brick). If I were doing a lot, I'd throw an old blade on my vertical bandsaw and go to town.
 
I ended up making a miter box like jig to make sure, and using a cheap job box saw. Would have used the table saw, but I don't have any old cheap blades, and the only hardware store near me only sells nice expensive blades. Wasn't bad.

The far less pleasant part of the build so far was using a 3.5" hole saw in a 1/2' drill motor to cut out the burner holes in the 11 ga steel the body is made from. If I do this process again, I am buying a plasma cutter first.

Will post photos when complete. Thanks for the help guys.
 
You must log in or register to reply here.
Back
Top