On 21 Dec 2011 03:53:33 GMT, "DoN. Nichols"
wrote:

[...]

One of the joys of the 9x20 is the clutch at the lowest speed which
effectively limits the available torque. Changing the cutter geometry
stopped the clutch dis-engaging during the last couple of passes which
was a problem before. There are those who disabled their clutch by
epoxy. I have not addressed that because I tend to use higher speeds
most of the time but it may be something I shall have to look at.

It seems that there is benefit from that -- giving you a clue
that things are not as they should be.

Not really. It disengages far too early rendering the low speed
useless.

I use RapidTap, seems to work fine.

Sounds good.

I do have a threading indicator but a cursory inspection would suggest
that it is not working. In any case I felt I wanted to take that
variable out of the equation for the moment. If I do more of this I
shall re-visit it.

What do you see which indicates that it is not working

What you should see, if it is working properly a

1) When you crank the carriage from side to side without the
leadscrew turning, the dial should rotate.

2) When the carriage is stationary, but the leadscrew is turning
the dial should rotate.

3) When the half-nuts are engaged (for threading, or likely on
some lathes, for longitudinal feed as well), the dial is
stationary.

I do not think it turns at all. Pending detailed assessment.

[...]

So -- with the threading dial, you engage on your selected
number, wait until you get to the runout groove

That feature was not an option on the current project.

and disengage, crank
back the cross-slide, crank the carriage clear of the end of the
workpiece, crank the cross-slide back in, advance the depth of cut on
the compound, and wait for the right number to come up before engaging
the half nuts again. Note that the half-nuts won't engage at the
mid-points between marks, so you can start to engage about then and it
will fall in at the proper point. (And, if you start far enough clear
of the end of the workpiece, you can make sure that it is on the proper
number, and disengage if necessary.

That I was not aware of. That will make things easier when I do this
in future. I wondered how to hit the mark at 150 rpm.

And -- you don't have to stop the spindle and reverse it to do
this.

All in all I would like to thank everyone for their helpful advice. I
feel almost like a proper machinist now.

Being able to single-point cut threads does make you feel like
that, doesn't it?

How did one live without a lathe?

Michael Koblic,
Campbell River, BC