[cange]

Hi all having trouble to make decent finish on my cnc converted lathe

Getting random strings (check photo)
So min diameter 10mm
Max diameter 29
Spindle rpm 1800
Feed 0.15mm per revolution
Insert 55 degrease 0.4 mm tip

Any suggestions where i need to look to make better finishes

[zumone]

Hi all having trouble to make decent finish on my cnc converted lathe

Getting random strings (check photo)
So min diameter 10mm
Max diameter 29
Spindle rpm 1800
Feed 0.15mm per revolution
Insert 55 degrease 0.4 mm tip

Any suggestions where i need to look to make better finishes

Do you have a centre in the end.
What kind of material is it.
Are you using the proper chip breaker for the material.
What depth of cut are you roughing and finishing at

[the_gentlegiant]

What depth of cut are you at? Your finish looks like that of a loose machine. Best way to get better results from a loose machine is to drive it harder. A heavier cut will push all the slop in the machine against the stops and will eliminate a lot of your finish problems. That finish looks like the machine dancing around within it's slop envelope under too light of a cut.

Basic cold rolled steel is not great for fine finishing either.

Dave

[mbservice]

Check your backlash that tool is jumping possibly due to x and z axis not moving correctly or as previous poster said use at least 1mm finish cut to push the job

[positiverake]

Yes more depth of cut