Carbide inserts

Got some carbide inserts off eBay, nice and cheap, for playing about with.
The main reason I got them was to use in a flycutter that I'm making (a
T-shaped one like the Japanese guy with the web site made). They're
triangular with a hole in the middle. I notice that there's no relief - if
they were mounted on a lathe tool, set horizontally, the face/edge towards
the workpiece would be vertical rather than sloping away a bit. Are these
intended to be used on a lathe, or are they for something else?
Having received them, and looking at the selection of broken lathe tools I
inherited from a mate, it ocurred to me that I could braze an insert onto
one and make a long-lasting tool. Can these carbide thingies be ground to a
suitable shape and still work?
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In message , Wally writes
They should be held with negative rake, i.e. tilted forward to provide clearance.
Yes, but you will need a 'green grit' wheel or diamond stone, and 'suitable shape' may not be the same as with high speed steel.
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So that the top face is tilting down towards the workpiece? Won't that prevent it from 'digging in', if you see what I mean?
I tried with a carborundum stone for a while last night - didn't make much difference, but the stone was spinning fairly slowly.
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It won't - not hard enough. You need a silicon carbide abrasive, not aluminium oxide.
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I thought carborundum was silicon carbide...
Regards, Tony
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Tony Jeffree

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