help with logan lathe #820

[timalready1]

I saw on some previous posts that many of you have experience with these
I recently picked this up with much excitement

However it seems the chuck doesn't spin true
(forgive my lack of proper terminology, im new)
It is bolted to a flange that threads on to the main shaft or spindle?, and it continues to come loose quickly, even when i try to really get it tight it still doesnt spin true and eventually comes loose

The bearings on that shaft seem ok

any ideas why it comes loose?
can i use a thread locker?
is the flange available that the chuck is bolted to?

I really appreciate any help

Thanks
Tim

 

[aonemarine]

Don't use thread lock!!! Which direction are you running the lathe???

 

[Philjoe5]

Tim,
A brief introduction in the Welcome section would be helpful. Tell us about yourself and what your interests are.

Let me see if I understand the problem you're having.

It is bolted to a flange that threads on to the main shaft or spindle

That flange is called a backplate and your lathe chuck bolts to it. This is standard practice for the Logan 10" lathes.

and it continues to come loose quickly, even when i try to really get it tight it still doesnt spin true and eventually comes loose

Are you saying the backplate with the chuck attached to it is coming unscrewed when you run the motor for a while? If so, I would guess you're running the lathe motor in reverse, possibly right after running it in forward speed. That's not necessarily a problem, it's just the way things work and there are ways to avoid it.

New backplates are available from several manufacturers, but first you need to isolate this problem or at least describe in a little more detail exactly what you're doing when the problem occurs.

Phil

 

[timalready1]

Yes the backplate with the chuck attached to it is coming unscrewed from the spindle when I run the motor but not for a while(seems to happen right away). Is it just floating on the threads and the pressure from cutting keeps it tight and when i shut it off the freewheeling lets it spin a little? Maybe thats normal? if so i think i will still need a new back plate. When i tighten it up it has a fair amount of runout right away and when i stop it the backplate is loose on the spindle.

 

[aonemarine]

Sounds like there is something else going on there. Check and measure the spindle threads and the threads in the back plate and check to make sure its fully seated.