According to Harold and Susan Vordos :

"DoN. Nichols" wrote in message
rvers.com...

[ ... ]

Yes -- but that needs greater skill in grinding the tool to go
into the boring head.

Yep, detailed instructions for which I provided, although they were directed
towards a different individual, one that hopes to use the process in the
near future. It has been a learning thing, of sorts, for those that
haven't been there. I was fortunate (?) to have visited the problem some
time ago and solved many of the issues.

And it was nice of you to share that information.

Sometimes, it may be easier to use the hole saw
followed by the boring head with standard boring bars. After all, the
original poster does not yet have tool grinding skills. (Nor do I
remember whether he has even indicated that he has a bench grinder.)

[ ... ]

Agreed. My conversation with Peter evolved well after the fact, and my
comments weren't necessarily directed towards Bill. Not that he might not
benefit, mind you. The trepanning method I discussed is a wonderful backup
for that special job that comes along and there's no reasonable method
otherwise. Good example might be the blanking of many round pieces from
plate or sheet, where a center hole may not be permitted, ruling out, or
seriously limiting a hole saw.

Agreed. Though the Roto-Bor which I mentioned (if available)
could have the spring loaded pilot point on a small disk of sacrifical
metal placed over the workpiece. (But the shape of the cutting flutes
on it result in a sharp-edged disk, so they are better for holes than
making disks.

Grinding a tool for trepanning with a boring head does require some skill,
of that there's no question, but if I can master the technique, I can't help
but think that others can as well. What's important is to understand how it
cuts, and what clearances and rake are necessary. The rest is just applying
the concept to the tool. If a person can grind their own lathe tools,
there's very little difference in grinding a trepanning tool.

The primary thing is that you need a different trepanning cutter
for each size of hole, while a lathe tool will work through a wide range
of sizes. (I don't think that I saw this explicitly mentioned in the
discussion.) This means that I would probably not do the trepanning
unless it was a serious improvement over the alternatives possible with
my existing tooling.

Enjoy,
DoN.

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