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Harold Hall's precision grinding table
Bluechip:
That type of countersink / hole de-burrer or whatever is made larger than 20mm .. here's a source if you happen to have some £140 looking for a new home .. :scratch:
http://www.engineering-supplies.com/sub/519/countersinks/
The usual included angle for a c/sink is 90 deg AFAIK, except in years gone by when 82 deg was used for 'raised csk.' or 'instrumentation head' screws ..
I don't suppose they would be difficult to make if you just wanted a special. They only appear to be a transverse hole in a bit of round silver steel stock, then machined to a point. Never made one for all that ..
Dave BC
Bogstandard:
There is a little more to them than that Dave, they actually have a relief grind done on them.
If you look at the very tip, it should be an elliptical type of shape rather than going to a normal point.
I have resharpened mine using a half round Swiss diamond file around the edge of the thru hole, and that seemed to do the trick.
Not bad for a cheapo set of five bought about 10 to 15 years ago.
John
Bluechip:
--- Quote from: Bogstandard on June 04, 2011, 02:15:15 PM ---There is a little more to them than that Dave, they actually have a relief grind done on them.
If you look at the very tip, it should be an elliptical type of shape rather than going to a normal point.
I have resharpened mine using a half round Swiss diamond file around the edge of the thru hole, and that seemed to do the trick.
Not bad for a cheapo set of five bought about 10 to 15 years ago.
John
--- End quote ---
Hi John
Another of my illusions gone ... but I'll certainly take your word for it. Did idly look at them when I got them , and wondered how they managed to cut.
But got no further than that.
However, cut they certainly do. I find watching the thin, crinkly ribbon emerging most satisfying ... :thumbup:
Which probably explains the excessive depth of some of my c/sinks .... :doh:
Dave BC
xo18thfa:
--- Quote from: wongster on June 03, 2011, 08:22:31 PM ---Thanks John, Roy, and Bob. This will give me the courage to ask another "how to use..." question on using splitting saw. Will ask in the right thread.
Bob, you mentioned a pilot hole before countersink. I did the hole first and then apply the countersink to it. Hope I didn't do anything wrong.
Regards,
Wong
--- End quote ---
Wongster: I just drill a very small pilot hole first, countersink then follow up with the full hole. If you drilled to main hole first, you'll be fine. Just run slow speed with oil. You'll be OK.
Those "0 flute" countersinks like someone showed are nice. I need to get some.
Bob
wongster:
--- Quote from: wheeltapper on June 04, 2011, 12:51:08 PM ---The countersink on the plan looks to be 20mm dia and 60 degree.
but I didn't worry too much about that.
It's only got to hold on to the ball, it's not that critical. the idea is to make the sinks first then assemble the bits roughly and measure how long the bottom spacer needs to be.
Roy.
--- End quote ---
That's reassuring enough. I'll trying using my 90-degree and give it a shot.
Thank you.
Regards,
Wong
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