I tried out my new Powermatic Mortiser yesterday with a CMT 3/4″ hollow chisel bit and found that one side of the square cut would always have a cup (not square). I turned the chisel and found that the cupped side of the hole followed the way the chisel was turned. I assume it is not the machine but the bit. Is this a common problem? Can someone give me the name of a quality tool manufacturer who makes this bit. Clico does not make this size.
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Hollow Chisel Morticer bits
I think Lee Valley sells some good ones
The cyo is coming from the
The cupping is coming from the round drill bit that has extended farther on one side than the outside of the hollow chisel on one side. Make absolutely sure the drill bit is centered properly in the chuck and you might raise the bit a tad so it doesn't extend so far past the tip of the hollow chisel mortiser. I run 1/4".. 5/16".. 3/8".. 1/2" and 3/4" CMT's in my Industrial floor mortiser and don't have the problem.
Good luck....
I have had the same issue with some of the lower priced chisel sets. I slightly reduced the diameter of the drill bit by holding the edge of a sharpening stone flat against the side of the chisel with the machine running. This eliminated any portion of the drill bit that extended past the edge of the chisel.
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