I may have a long boring bar for sale

On 2008-06-11, John R. Carroll jcarroll@ubu wrote:
wrote:
On Jun 10, 9:21 pm, Ignoramus13673 ignoramus13...@NOSPAM.
13673.invalid wrote:

Think again.

And you will realize that a "collet" needs to be compressed which
your extension would not be.

Uh, wha? Boring heads are not typically held in collets. They have
their own arbors - the arbor threads into the boring head.

However, you're right in that R8 is not self locking. The extension
would have to have a small draw bolt to hold the boring arbor inside.


Your best bet would be to get a shaft like 3/4", and bore a hole to
fit your cutter, and use a weld-on style setscrew to hold it. And mae
the cuts light.

Or just get a long boring bar (roughly the same idea). However, this
is not ideal, and it sounds like Bill doesn't want to do this.

A spindle extension would likely have the most rigidity as it would be
larger in diameter than a boring bar extension. May have to lower the
knee to adjust the boring diameter, but sometimes life sucks.

An extension could be turned on a lathe. PITA though. In fact, I'd
probably just turn a male R8 taper on to one end (not trivial, but not
murder either), and the boring head thread in the other. Turning a
female R8 taper would be *way* more involved, and it likely wouldn't
be concentric enough to do perform useful work beyond holding a
single- point tool anyway. The boring head thread could be completed
in 30min or less.

Feed the table/saddle up.
Sheesh, you youngsters G





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