I'm trying to repair a loader for a machining cell. A shaft that drives the loader between
machines is highly fubared. 25mm shaft that is now 22mm where one of the bearings ride.
No wonder we were getting torque alarms.

Anyway, my co-worker welds up the shaft for me. Btw, wrapping things with fiberglass tape
that you don't want weld on is fairly handy. He got carried away slightly and welded a
few threads that the bearhug nut uses to secure the bearings.

No big deal, 10 mm of threads, 1.5mm pitch. I'll just put the lathe in neutral and turn
the chuck by hand since this is an imperial machine and you can't open the half nuts.

Read the charts, put the gears and levers in the right place, pick up the thread and damn,
I'm cutting where I shouldn't be.

Back away from that part Wes, something is wrong.

I spent over an hour looking all over this lathe, reading the chart over the QC gearbox
and finally I started working though the ranges and measuring pitch. I finally found a
combination that cut a 1.5 mm pitch but it isn't what the chart indicated. This is on a
Servoshift Leblond. I had the right change gear combination installed.

The moral of the story, if you are going thread something that really needs to not be
screwed up, either know your lathe or make a test pass on scrap to check your setup or do
both.

Wes

Wes wrote:


Read the charts, put the gears and levers in the right place, pick up the thread and damn,
I'm cutting where I shouldn't be.

Back away from that part Wes, something is wrong.


The moral of the story, if you are going thread something that really needs to not be
screwed up, either know your lathe or make a test pass on scrap to check your setup or do
both.

Wes

Wes, If I'm picking up a thread like that I make a test pass above the major
dia. first to see if things look right.

Best,
Steve
--


Regards,
Steve Saling
aka The Garlic Dude ©
Gilroy, CA
The Garlic Capital of The World

http://tinyurl.com/2avg58

Wes writes:

... or make a test pass on scrap to check your setup or do both.

Or make a "scratch cut".

On Sat, 07 Nov 2009 18:45:26 -0500, Wes wrote:

I'm trying to repair a loader for a machining cell. A shaft that drives the loader between
machines is highly fubared. 25mm shaft that is now 22mm where one of the bearings ride.
No wonder we were getting torque alarms.

Anyway, my co-worker welds up the shaft for me. Btw, wrapping things with fiberglass tape
that you don't want weld on is fairly handy. He got carried away slightly and welded a
few threads that the bearhug nut uses to secure the bearings.

No big deal, 10 mm of threads, 1.5mm pitch. I'll just put the lathe in neutral and turn
the chuck by hand since this is an imperial machine and you can't open the half nuts.

Read the charts, put the gears and levers in the right place, pick up the thread and damn,
I'm cutting where I shouldn't be.

Back away from that part Wes, something is wrong.

I spent over an hour looking all over this lathe, reading the chart over the QC gearbox
and finally I started working though the ranges and measuring pitch. I finally found a
combination that cut a 1.5 mm pitch but it isn't what the chart indicated. This is on a
Servoshift Leblond. I had the right change gear combination installed.

The moral of the story, if you are going thread something that really needs to not be
screwed up, either know your lathe or make a test pass on scrap to check your setup or do
both.

Wes

Or do a ghost pass where the bit won't touch the metal but you can see
where it might.

Bet you won't forget that lesson any time soon!

On Sat, 07 Nov 2009 18:45:26 -0500, Wes wrote:

I'm trying to repair a loader for a machining cell. A shaft that drives
the loader between machines is highly fubared. 25mm shaft that is now
22mm where one of the bearings ride. No wonder we were getting torque
alarms.

Anyway, my co-worker welds up the shaft for me. Btw, wrapping things
with fiberglass tape that you don't want weld on is fairly handy. He
got carried away slightly and welded a few threads that the bearhug nut
uses to secure the bearings.

No big deal, 10 mm of threads, 1.5mm pitch. I'll just put the lathe in
neutral and turn the chuck by hand since this is an imperial machine and
you can't open the half nuts.

Read the charts, put the gears and levers in the right place, pick up
the thread and damn, I'm cutting where I shouldn't be.

Back away from that part Wes, something is wrong.

I spent over an hour looking all over this lathe, reading the chart over
the QC gearbox and finally I started working though the ranges and
measuring pitch. I finally found a combination that cut a 1.5 mm pitch
but it isn't what the chart indicated. This is on a Servoshift Leblond.
I had the right change gear combination installed.

The moral of the story, if you are going thread something that really
needs to not be screwed up, either know your lathe or make a test pass
on scrap to check your setup or do both.

Wes

If there's some thread there already do "air threading" -- line the point
of the tool up with the valley (or point) of the thread you're cleaning
up and let 'er rip (or crank the thing by hand, as appropriate).

You know what to look for.

--
www.wescottdesign.com