Cutting Hole in Cement Block Chimney.

If you didn't break the tile, it was a success. Are you putting in a clay thimble?

No room, 6" flu and 6" pipe that's it. What is the issue with no thimble?

I've only read page one of replies. After posting my reply, I'll more than likely read the other pages. I'll give you my experience/opinion. If you can find a 6 inch diamond hole saw, that's the way to go............ALL THE WAY THROUGH. Fast, neat, clean, and done. Myself, I've used a hammer drill. Draw a 6 inch circle. Then a series of 1/4 - 3/8 inch holes around the circle, through the block. Drill some holes in the center of the circle to weaken some more. Then carefully tap out the block with a drilling hammer (small sledge). NOW, you still have to put a hole in the flue liner. That may be difficult (But can be done). Depending on how hot the tile has gotten, you may go through many masonry drill bits. If you try drilling through the block, and tile all at once, you'll smoke bits left & right. Do the cement, then the flue. The next time I do what you're trying to do, I'll find me a 6 inch diamond hole saw. You'll want position #1 in your picture. You'll hit webbing in position #'s 2 & 3. I like the sand idea, but not necessary, Especially with a hole saw. Oliver I also like the water spray idea.

Just a few thoughts before I leave for work.

The 6" inch hole saw made such a tight hole (insert joke here) that I had to use a wooden block and hammer to force the stove pipe into the chimney. However, it turned out great, but had absolutely no adjustability.

Thx EWF, that appears to be the plan (as much as I ever have a plan). Heavy gauge HeatFab, jam it in there, seal and pray.

"I love it when a plan comes together" thx Hannibal.

oliver power wrote:I've only read page one of replies. After posting my reply, I'll more than likely read the other pages. I'll give you my experience/opinion. If you can find a 6 inch diamond hole saw, that's the way to go............ALL THE WAY THROUGH. Fast, neat, clean, and done. Myself, I've used a hammer drill. Draw a 6 inch circle. Then a series of 1/4 - 3/8 inch holes around the circle, through the block. Drill some holes in the center of the circle to weaken some more. Then carefully tap out the block with a drilling hammer (small sledge). NOW, you still have to put a hole in the flue liner. That may be difficult (But can be done). Depending on how hot the tile has gotten, you may go through many masonry drill bits. If you try drilling through the block, and tile all at once, you'll smoke bits left & right. Do the cement, then the flue. The next time I do what you're trying to do, I'll find me a 6 inch diamond hole saw. You'll want position #1 in your picture. You'll hit webbing in position #'s 2 & 3. I like the sand idea, but not necessary, Especially with a hole saw. Oliver I also like the water spray idea.

This is how I would do it. And how I've done similar.

Had to put a range hood vent in when I rebuilt the fiancée's kitchen. Her house exterior walls are cinder block with metal lath and stucco.

Using my Porter-Cable 1/2 inch combo drill/hammer drill, and a new 3/8 inch masonry bit, I just made a series of holes about an inch apart, centered on the drawn outline of the vent duct.

Then I played "connect-a-dot" with a cold chisel to take out the remaining bits of block between the holes.

You'd be surprised how quickly a new masonry bit in a hammer drill goes through cinder block and brick. And how easily the raggedy edge of that opening can be caulked around whatever metal tube is put into it using refractory cement.

Paul

You'd be surprised how quickly a new masonry bit in a hammer drill goes through cinder block and brick.

With the Hilti on hammer setting, new Bosch drill bit and very little pressure (thx mcgiever) it went 123. I was surprised too.

coalnewbie wrote:No room, 6" flu and 6" pipe that's it. What is the issue with no thimble?

The thimble makes a nice snug fit on the stovepipe (and easy to remove at shutdown ) and should be cemented clean and flush with the inside wall of the chiney tile,don't forget to pitch it upward. Without a thimble, you would need to cement the stovepipe in and that will disappear at some point in time. Thimbles are cheap, probably under $20 and well worth it in the long run.