SB 10L old single tumbler catalogue 187A

Hello: Have been given lots of help and encouragement in this matter. Problem as follows
(it was there when I bought it )
trouble. Lead screw will not turn when under load. ie cutting threads or using clutch.
removing QC box discovered the gear which meshes with the lead-screw gear.(the last gear) will slip on the shaft. I need some where to get a
dissembly proceedure. undoubtedly there is a key
missing. but no keyway slot visible on that end of the shaft. No set screw no no nuthing. scraping away paint from outside box however still uncertan on how to get the thing apart ..with some grace.. have photos which show the gear etc.....there are no broken gears
..I have removed the pin holding the splined gear
so I could slide it away from troublesom spot
for observation. the troublesome gear has a small
notch which is about .125 deep..
anything fellows? [email protected]

On my qc gearbox there were spacer bushings. It sounds like you micht be missing one along with the key. Best look up the drawings for that lathe or call Rose at Partsworks for a manual.
Paul

Amazing, I found the key to disassemble the single tumbler job. at that very moment a man from latheparts called me . we talked and i wanted to e mail him. evidentally I had the email address incorrect the msg bounced. any one else having troubles with disassembly of that box perhaps I could help out by e mail, with photos etc.
my findings were a sheared pin inside the last drive gear. not yet removed, but there is hope
bye

I have the same machine! The key in question is made from 1/4" square stock,turned round for 1/8" and left square for 1/8". I got the machine FREE for the same reason,wouldn't drive! seems this small key was expendible and made to give up or shear if the saddle hit the head or tail stock so as to do very little damage. I pulled the gear with a gear puller from Harbor Freight and made a new key on a lathe at work.Hope this helps.