Re: What are these? (Using reversed cutoff blades)

On 2009-06-21, Joseph Gwinn <joegwinn@xxxxxxxxxxx> wrote:
In article <slrnh3qv08.fo5.dnichols@xxxxxxxxxxxxxxxxxx>,
"DoN. Nichols" <dnichols@xxxxxxxxxxx> wrote:

[ ... ]

O.K. My default speed is 550 RPM -- the middle pulley on direct
drive.

OK. No difference. Actually, I just figured out why I couldn't get to
2000 rpm indicated on the control dial, hitting a hard stop at 1900:
The VS assembly was misassembled. So, I may be going a bit faster than
intended.

Oops! Do you have a tach to check your spindle speed with?

I recently did some parting of 3" diameter 12L14 with no
problems.

Using a HSS T-blade if I recall. How big?

Hmm ... let me go check ... 1/8" wide at the top.

Sounds like the blade in a BXA-7.

Yep -- precisely (or at least the Phase-II clone of the BXA-7).

[ ... ]

I have not tried anything larger than a 6061 aluminum tube 4" in
diameter, held in the 3-jaw chuck. The walls are about 3/8" thick.
This worked, yielded a 0.007" taper in 8". It will be a few more trials
before I conclude that this is the inherent taper.

Hmm ... not sure how much cutting pressure deflection there was
in the aluminum. How long was it? How sharp was the tool?

The whole piece was ~12" long, with ~3" in the chuck. The tool was
carbide, ordinarily but not extraordinarily sharp.

O.K. Did you try applying a known force to the side while
measuring the deflection out near the end? I've got a force gage, and a
dial indicator in the toolpost would do it.

I've threaded 4" aluminum pipe for making a circular waveguide
-- but I made a free spinning tailstock chuck to grip the interior of
the workpiece where I was threading.

I was of course not supporting the tailstock end.

Though you might want to while doing the setup, to make sure
that everything is true to the chuck before you loosen the tailstock
support and try your turning.

The reason to use a tube was to reduce the weight pulling the piece
downwards in the chuck.

Well ... the downwards pull will have very little affect on the
resulting diameter when starting from 4".

It's the twisting in the chuck that I worried about.

Again -- start with tailstock support, and then loosen it once
the headstock chuck has a good grip.

[ ... ]

Evilbay? It would be hard to hurt one of these holders.

There is that -- but I've stopped buying much there since they
started forcing their sellers into accepting only PayPal. I just don't
like the idea of being forced into using a payment service which is also
owned by eBay. :-)

Why is that a problem? I've had no problem. Not that I buy that much.

It is if you refuse to get an PayPal account -- at least
recently.

PayPal is a problem for sellers more than buyers.

I just don't like the idea of giving a third party the ability
to withdraw from my bank account.

Perhaps I could create a separate account, in a totally
different bank chain, to allow PayPal access to.

They claim that it is to reduce scams, but I think that it is to
increase their income. :-)

Probably both. But they do seem to be reducing scams by driving sellers
away.

And buyers like me. :-)

[ ... ]

I do that too, now that the lathe has been tightened up. But I can be
more aggressive with the reversed setup operated manually, with feel.

O.K. I usually go for power feed to free hands for squirting in
cutting lube.

I do that too, but I'm more comfortable doing it manually when I'm being
aggressive, although I've now done it enough to be comfortable with a
faster powered feed.

O.K.

As for squirting coolant, I use a mister for that, so no hands are
required. You can tell from sound alone if there is too little coolant.

While I was using a bottle of Rigid threading oil with the
hinge-out spout which makes it fairly easy to get it into the groove.

Since I have had asthma for all my life, I don't like the idea
of a mister. *Maybe* a Micro-Drop setup.

Enjoy,
DoN.

--
Email: <dnichols@xxxxxxxxxxx> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
.

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