Hi Gerry,
Ah, now that makes sense. Having not tried any boring yet, but
having recently bought a set of 3/8" carbide boring tools to try,
I've been following this discussion to learn the issues.
Can someone confirm my thinking?
As far as I can see, springing of the boring bar itself should be by
a pretty constant amount. After all, the length of bar extended
stays constant. So spring should be determined only by the depth of
cut and advance rate. Minimise both.
Of course, spring of the workpiece is another matter. While that too
can be minimised in the same way, the amount of workpiece spring
varies along the job as you move between the t/s and h/s (and
possibly steady) support points.
Is that about it?
John
--- In 7x12minilathe@..., "hanley_gerald" <gbhan@...>
wrote:
Thanks to all who replied. For the benefit of all--I've been using
the compound screw. That appears to be the problem.
This the way you learn!
Gerry
--- In 7x12minilathe@..., "Charles E. Kinzer"
<ckinzer@> wrote:
If the problem is that the hole is bell mouthed, then springing
would be a concern. Otherwise the tool is, for some reason,
simply
cutting a taper.
This same thing came up on one of the minilathe sites recently
and,
as Kevin just suggested, in that case it was because the tool was
moved with a not exactly parallel compound instead of moving the
tool
with the carriage.
Chuck K.
----- Original Message -----
From: Kevin Jones
To: 7x12minilathe@...
Sent: Wednesday, March 07, 2007 11:09 AM
Subject: [SPAM] Re: [7x12minilathe] boring
>The resulting hole is smaller (0.010+) at
>the tailstock end. I've read about boring bar "springing" and
have been
>careful to try to avoid this.
The springing is going to have a lot to do with the boring bar
length
vs diameter (or cross section if its not round). How deep is
the
hole
you are boring, how long is the boring bar, and what size is
it ?
Also you are not using the compound screw to advance the
boring
bar
into the work are you ? Unless you've set the compound angle
using an
indicator its most likely not set to be parallel to the
spindle.
If
its not parallel to the spindle then you are boring a taper
using
whatever angle the compound is set at.
Regards,
Kevin Jones
Louisville, KY
