Chester 920 traverse issue

[flintandsteel]

Had this lathe about10 years now. Sorted, renewed and fixed most things and it does what it should.... till this morning.
As the table moves along the travers screw (not sure of technical name) it reaches a point where something must jam up as it gets closer to the chuck- sufficient to kick it out of gear.
Checked the under table box and all fine in there.
Only thing I did this morning was to change up on the gear box, try the speed then back to where it was.
Reset the drive gears so it can power the traverse screw again (table not engaged) and runs fine.
Fingers crossed engaged the table and it travelled the full length of the bed till about 6" off the chuck then it kicked out of gear again.
Thinking gear box issue. Just tried it in a different gear - same problem
Thoughts?

 

[flintandsteel]

Had a look in the gear/speeds box and all looks fine.
No bits of metal or teeth lying around
Worn transverse feed bar?

 

[ChaiLatte]

When you traverse the carriage along the bed manually, using the handwheel, does it feel any harder at the same point as the power-traverse struggles?

Have a look at the rack in which the manual handwheel pinion engages to make sure it is clean and sound at the problem point.

I think what you call the traverse screw would normally be called the leadscrew. Have you checked that is not burred or bunged up at the problem point? You can clean the leadscrew by setting it moving using the gearbox, making sure the carriage is not engaged to it and passing a piece of string round it in a U-shape. Holding both ends of the string, it will clean out the groove of the thread.

 

[Amplidyne]

As ChaiLatte says, it sounds more like either a problem with muck on the leadscrew itself, or with the saddle movement sticking somewhere rather than an actual gearbox problem. Sounds as if it's loading up the leadscrew / drive at some point, and kicking it out of gear somehow.