On Fri, 12 May 2006 16:19:33 -0700, Eric R Snow
wrote:

On 12 May 2006 20:34:11 GMT, (DoN. Nichols)
wrote:

According to Eric R Snow :
On 12 May 2006 05:23:43 GMT, (DoN. Nichols)
wrote:

[ ... ]

Yep -- re-set the gears. Then you should be fine.

[ ... ]

DoN,
This business with the 120 and 127 tooth gears was what I had posted.

Yes -- I saw your posting *after* I posted my followup.

How the gear, either the 120 or 127, was not being used as an idler. I
guess I should have made it more clear in my first post.

From the chart, it is expected for the 127 tooth to be the one
used as an idler gear.

I tend to post a lot more detail, simply because if someone is
having problems of this nature, the more detail the better the chance
that he can make things work -- and avoid similar problems in the
future.

One thing which I did *not* get around to mentioning is that he
needs to bear in mind that whenever he is cutting metric threads, that
he should leave the half-nuts engaged the whole time, and reverse the
lathe to get to the start for another pass. This is a side-effect of
the threading dial just plain not working with metric threading and an
imperial leadscrew (or for that matter, with imperial threading, and a
metric leadscrew).

I also should mention that this can be a serious pain when
cutting threads to a shoulder, unless the lathe has a quick-acting
clutch to stop the spindle before there is a crash.

Enjoy,
DoN.
Greetings DoN,
My post was aimed at the OP, not you. Once again I fail to make myself
clear. Sometimes when I proofread my stuff I discover all sorts of
things which I have left out, or that make assumptions that a reader
might not. This business with metric threading and threading to a
shoulder has caused me to take a look at installing a dog clutch just
for this purpose. If the spindle only has one gear on it that engages
the the threading gear system then if that gear is driven by a dog
that can only engage at the same point in rotation then any thread can
be cut without fear of losing position.
ERS
===================================
If you are serious about [low volume] metric threading to a
shoulder with an inch lead screw, take a close look at a spindle
hand crank. This will allow lyou to get as close to the shoulder
as you desire and have time to retract the tool and reverse the
spindle to return to the start point. [I am assuming that you
know you can't use the thread dial and must not open the half nut
if you using metric/inch change gears.] If you anticipate high
volume metric threading you may want to check the cost/difficulty
of swapping the inch/metric lead screw.

see http://www.mcduffee-associates.us/ma...ndle_crank.htm
to see a hand crank we manufactured in class for exactly this
purpose.


Unka George
(George McDuffee)

There is something to be said for government by a great aristocracy
which has furnished leaders to the nation in peace and war for generations;
even a democrat like myself must admit this.

But there is absolutely nothing to be said for government by a plutocracy,
for government by men very powerful in certain lines and gifted with the "money touch,"
but with ideals which in their essence are merely those of so many glorified pawnbrokers.

Theodore Roosevelt (1858-1919), U.S. Republican (later Progressive) politician, president. Letter, 15 Nov. 1913.