In article ,
"DazFNQ" wrote:

----- Original Message -----
From: "Joseph Gwinn"
Newsgroups: rec.crafts.metalworking
Sent: Monday, June 16, 2008 11:25 PM
Subject: Shenzhen Lathe problem - Hare & Forbes AL-335


In article ,
"DazFNQ" wrote:

Ha It gets better, in the Hare & Forbes brochure it says theat the
leadscrew
is metric, but another source of information for the same lathe says that
it
is an imperial leadscrew.

Have discovered that its pitch is 3mm and it has 8tpi (butress thread)

Can't be both. 8 tpi is (1/8)(25.4)= 3.175 mm pitch, not 3.000 mm pitch.

It's close enough that a thread pitch gage may have difficulty
distinguishing unless one takes the leadscrew off the lathe.

A better way to measure in place is with a dial indicator stuck to the
bed indicating horizontal travel of the carriage with half-nut engaged
while manually turning the leadscrew and counting turns.

Joe thanks for the tip.

After measuring the carriage travel based on leadscrew revolutions

Leadscrew Revs Dial Indicator Gauge
1 0.125
2 0.250
3 0.375
4 0.500

So you were correct, thanks.

Bingo: exactly 8 tpi. Welcome.


More importantly these bloody chinese
documents really are crap as they go on to say that the leadscrew pitch
is 3mm 8tpi.

I bet the Chinese-language manual is no better. Attention to detail is
language-independent, and arabic numbers are used in both languages.

I would make a xerox working copy of the manual, and start to annotate
the copy in pencil. The reason to do this with pencil on a copy is that
not all discoveries will hold up, so one needs to be able to edit.
After a year, things should have stabilized, and one can use ink in
confidence.

Joe Gwinn