Help with Lathe compound movement.

[CoyoteJews]

I have a 12x30 craftsman commercial lathe and the compound is moving while I do turning operations pushing the tool back from the workpiece. I have to hold the crank on the compound still while cutting to keep it from backing off. I have tightend everything in the immediate area to no avail (everything was already tight).

Im really just trying to figure out how to make this stop and get the compound to stay still. Any help would be greatly appreciated.

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[MrWhoopee]

Does the dial/screw turn as it backs off?

edit: If it's like this one, just lock it with the gib screws on the right side. Unlock only when you need to use the compound.

 

[CoyoteJews]

Yes the knob spins back as it goes

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[CoyoteJews]

Thank you much appreciated!

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[MrWhoopee]

Yes the knob spins back as it goes

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see my edited post above.

 

[markba633csi]

Sounds like your compound gib screws all need to be snugged up- there should be some resistance there when you turn the crank
It takes some time to adjust it correctly- you want it not so tight that it won't move but not too loose either
Same with the cross slide
Are you using a sharp tool? If your tool is dull and cutting forces are too high then the lathe will certainly groan and complain, push the tool back
(and possibly break something)

 

[ARC-170]

Craftsman lathes are not known for being the stiffest. You gotta know their limits: light cuts in steel (0.015"max) and about 0.025"max in aluminum. Tighten the gib screws as noted above and you should be fine.

I made a gib screw with a handle (like on a vise) that allows me to tighten it as needed. I got tired of using the wrench.

 

[jwmay]

1: Tool could be below center
2: Toolbit could have too much back or side rake.
3: Gibs could be too loose, but it’s not the end all be all.
4: I’m surprised nobody told you to toss your compound slide and go with a solid block yet. (Not a bad idea for most work).

All that said, I’ve experienced the same thing with my Atlas lathe, and was able to solve the problem by orienting the compound slide parallel to carriage travel.

I only ever see English (like from England) people orienting their compound like that. But I do almost no screw cutting. Which seems to be the American rationalization behind a 30 degree orientation.

Anybody know the correct term to describe our friends across the pond? Being American, I find myself broadly ignorant.

 

[wayback machine]

Anybody know the correct term to describe our friends across the pond?

Brits, or more properly, British - What I've always used.
Others may have more colorful terms :~)

 

[markba633csi]

Those who be fond of (and associated with) certain green citrus