Parting and compound movement...."newbie" question.

[Rif]

Hello,

When using a cutoff tool, on my SB13, I have noticed that my compound tends to move unless I have my compound gib tightened down to the point that I can barely move it with the compound handwheel.

I really haven't given it too much thought until I stopped by Grizzly, in Muncy, PA, last week and looked at the lathes there. (I was really looking for a 10 ton bench-top press; but, they didn't have it in stock.) I noticed that the compound slide on a new lathe is real smooth.

So, does my lathe need something fixed or is this normal?

Thanks,

Brian

[mochinist]

My compounds are locked down to where they wont move unless I am using the compound.

[Rif]

My compounds are locked down to where they wont move unless I am using the compound.

Do you loosen the gib when you need the compound?

Thanks,

Brian

[mochinist]

Do you loosen the gib when you need the compound?

Thanks,

Brian

yup thats what I do

[Teenage_Machinist]

Mine is tight so its tough to move but can be done.

[Rif]

Thanks! I won't worry about it then.

Regards,

Brian

[oldtiffie]

John Stevenson once answered this or a similar question by saying that he took his compound off his cross-slide/lathe altogether and made a "jacking" or "spacer" block that fitted between the tool-post and the cross-slide.

That's pretty reasonable as it doesn't take much to make, is easily removed or replaced and does the job nicely.

[piniongear]

Hello,

When using a cutoff tool, on my SB13, I have noticed that my compound tends to move unless I have my compound gib tightened down to the point that I can barely move it with the compound handwheel.
I really haven't given it too much thought until I stopped by Grizzly, in Muncy, PA, last week and looked at the lathes there. (I was really looking for a 10 ton bench-top press; but, they didn't have it in stock.) I noticed that the compound slide on a new lathe is real smooth.
So, does my lathe need something fixed or is this normal?

IMHO you really don't want to tighten down the gibs so tight that you cannot move the compound using the handle.
What you may have is a worn nut on the screw, or perhaps the screw has worn to the point that you have excessive play in the threads.

When using the cut off tool, center the compound upon it's base and make sure you have 'advanced' the screw thread forward to keep the thread engagement tight.
In other words, do not screw it in and then back it off leaving slack in the thread.
When you get ready to advance the cut off tool, have the carriage locked down to the bed. If you still get vibration, then you may need to tighten the compound gibs just a bit tighter....... pg

[dp]

I made a compound lock similar to Evan's threading stop shown at http://vts.bc.ca/metalshop/tstop/tstop.htm (but unfortunately the images are gone). It is a bar that clamps across the dovetails, in Evan's case, on the cross slide, but a smaller version works as well on the compound. Two ways to use it: abut the compound against the stop and there it will stay, or a threaded hex head bolt through the clamp pushes against the compound slide effectively locking it.

This stop is useless if your gibs are not properly snug. It only removes end play, not side to side or rotational movement.

Hopefully Evan's pictures will turn up again.

You should check from time to time the gibs on all your carriage components to ensure they're properly snug. That includes the front and back upper ways and lower guides, the cross slide, and the compound. And of course keep them oiled and the wipers clean. I'm going on and one here but stay with me - remove the ways wipers from time to time and move the carriage to the tail stock end to be sure you've access to any swarf that has gotten in the inter-wiper space. That stuff can kill your ways.

[Mark Hockett]

My lathe has a thumb screw lock on the compound that tightens against the gib.