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- May 16, 2016
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- 1,701
Back to the original question. My lathe came with a set of boring bars from 3/16 OD to 7/16 OD. They use a 1/8 round HSS tool bit. The set included two small v blocks that fit the lantern tool post that came with the lathe. I have only used the 7/16 OD boring bar. It has a lot of spring. And I mean a lot of spring. For example if I try to take a .010 cut with the 7/16 BB the actual cut is .005, maybe .006. The smallest hole I have been able to slip the 7/16 BB into is 5/8 ID. I don't have a 9/16 drill. It might fit into a 9/16 ID hole. It won't fit in a 1/2 ID hole. Based on my very limited experience I think that you could clean up a drilled hole taking very light cuts. Remember that a drill cuts a slightly larger hole than the size of the drill. Back to your 9/16 example you would probably need to drill a 1/2 or maybe 17/32 hole to end up with a 9/16 hole.
X2 on the 4 way tool post holder. Also the norman style qctp was designed in either the late 1800's or early 1900's. That's still pretty old school.
A .010 cut should be fine with a 7/16 bar. How much stick out do you have. To get that much spring I would suspect one of a few possible problems. Not enough clearance, a cutter that is not sharp, too big a radius, cutter not on centre line, Too much stick out, poorly supported and clamped bar. Have you checked all these things. Some photos might help.