Sometimes my countersink cuts a hexagonal-shaped hole instead of a round one, especially in plywood. Is this because I am using a hand drill instead of a drill press?
Leonard Lee’s book doesn’t discuss how to sharpen countersinks. Do they need to be sent to experts for sharpening? I don’t remember what kind of countersink mine is, but it has five evenly-spaced flutes and has “1/2-VA-HSS-USA-F00” written on the shank.
Janet
Replies
Here's a picture.
Janet
Janet,
What RPM are you running it at? Try slowing down to 150-250 RPM. The symptom you describe is usually caused by too high a speed.
TDF
Slower!?! I'd been doing the exact opposite, so the countersink could do its work quickly, before my hand had a chance to slip. (Kind of like carrying a full cup of coffee: It's more likely to spill if you move v-e-r-y s-l-o-w-l-y and keep watching the cup. Better to walk normally and not look at the cup at all.)
I slowed down and it worked out better, although not perfectly. But now I know that this is related to the style of countersink. Thanks, everybody.
Janet
These single-edge types of countersinks are the best i've found. Absolutely smooth, circular, and centered on the hole. I got mine at Boeing Surplus for 50 cents each, all sizes from 1/4" to 3/4".
As Tom said, slow it down. I have some countersinks (like yours) that will fit either in a handle or in a drill. I generally get better (not necessarily faster) results using the handle.
Sharpening a countersink can help and no, it's not a specialist job. See the flat face on the sink, in the bottom left of your photo? Give it a few strokes with a small diamond hone, the hone flat on that face.
HTH,
Graeme
Try http://www.wlfuller.com/. They make single flute countersinks for wood and metal, four-flute plug cutters (many sizes), as well as drill bits, tapered wood screw bits, and bit/countersink combinations for flat and hex head/washer type screws. I've used them for over 30 years. I sharpen mine by hand using a bench grinder, or a file. For an absolutely round hole, single flute cutters are best used in a drill press. Drill bit mounted countersinks are easily used in hand drills - tapered drill/countersink combinations drill thread, shank and countersink in one operation. I turn single flute countersinks slowly in most metals and fast in wood. I prefer spinning drill/4-flute countersinks in wood at 2000-rpm.
Namaste,
Gary
http://gwwoodworking.com/
Edited 12/26/2002 2:51:23 PM ET by Gary
Edited 12/26/2002 2:54:48 PM ET by Gary
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