Screw imprint on work while using power crossfeed

[Eliotmay]

Has anybody seen this? Running Logan 1820 on 1/2 in brass. When using power crossfeed the finish had an imprint like the crossfeed screw. With maybe a couple thou relief? Any thoughts?

 

[Eliotmay]

I meant lead screw- like imprint

 

[GK1918]

Not sure, are you facing and it looks like a phono record, if so try rounding the tool a little more rpms
with a slow feed. With brass it should look like a mirror. Thats all I can think of or Im not reading the
question correctly.

 

[HSS]

If I understand what you are saying, it may be an in and out movement of the chuck. I had the same problem on my SouthBend and resolved it by tightening the thrust bearing on the outboard end of the spindle. My thrust bearing behind the nut was originally a fiber washer and I replaced that with a set of very small bearings.
See if you can move the chuck left and right to the axis.

Patrick

 

[Cheeseking]

Are you moving the carraige slightly away from the face of the work (on the finish pass) before winding the cross slide back??

 

[TDHofstetter]

...and you're using zero or negative top rake, like you should for brass?

 

[Ray C]

This can also happen if your leadscrew or drivescrew are bent. As they spin, they put an uneven force on the carriage through the apron and if the carriage gibs are too loose, the movement shows-up in the workpiece. Check everything in the carriage drive train, clean the acme screw, check the thrust bearings ( as suggested below) etc. If your ways are worn badly, the problem might not be correctable.

Ray