What is this terracotta-like material, and how to notch it?
etting
| Posted in General Questions on
Can you tell what material the reddish enclosure around this electrical pedestal is made of? The shape and the smoothness of the sides make me think of terracotta, but from what I gather about terracotta, it’s usually finer, and although I’ve never lifted a big piece of terracotta, this weighs much more than I expected.
What would be the best way to cut a 4-inch square (or curved) notch out of the bottom edge? (Hitting or compromising the protection of any wires or cables isn’t a problem; I just don’t want to crack the whole thing.)
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It looks like a terra-cotta chimney flue liner to me. You can cut it with an angle grinder with a masonry cut-off blade, preferably a diamond wheel which is safer for that kind of cut than a friable wheel. Or there are probably reciprocating saw blades that would work as well.
Etting,
I agree, it looks like a flue tile. Some additional choices for cutting might be jig saw blades with grit coating or oscillating tool blades with grit or carbide teeth. Plan on it being very slow with these two choices. Sometimes slow makes for less unexpected fracturing. I have frequently found that reciprocating saws are too aggressive and the blades too long for this type of situation.
Thank you, Michael and Onslow. What do you think of drilling a series of holes, perhaps 1/2" apart, along the line I want to cut out? I have masonry bits for a regular drill and for a rotary hammer, which, on its hammer-and-drill setting, with a 3/16" bit, goes through the same thickness of CMU in a couple of seconds.
I *think* that would work; flue tiles are pretty tough, but success is not as guaranteed as it would be with any of the other methods mentioned. Though it is a good idea to drill holes at the corners of your cut first, to alleviate potential internal stresses. Maybe consider purchasing a flue tile to test your approach on first so you get a feel for it.
You don't want to use anything hammer or impact as it can crack. Those tend to be pretty hard, pretty much like a ceramic tile.
Simplest is as suggested above, angle grinder with a diamond wheel. Once you cut it out the piece, grind and round out any sharp corners to prevent future cracking.
You can also use a one of the diamond coated hole saws if you need only a small hole.
Thank you, Michael and Akos. It sounds as if the terracotta is harder and more brittle than a CMU; good to know. I don't have an angle grinder, but I do have the other suggested tools. I'll see which I can equip with the right cutting material least expensively.
you can put a masonry cutting blade in a skilsaw if you don't have a grinder.
That said, grinders are pretty cheap as far as power tools go -- use the guard and a face shield and safety glasses.
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Thank you, Stamant. I was surprised to find a highly rated Dewalt diamond cutting blade for a circular saw available for less than $11. If I go with that option, wearing a face shield is an important reminder--even if a circular saw is safer than an angle grinder.