Delta 50 lathe surface speed

[BetaBob]

I have a turret lathe with a Delta 50 controller and I can't get the constant surface speed to work on facing operation. No matter how I program it, it will start the operation fine but when it gets down to the center of the spindle the feed rate slows to a crawl. We're talking counting 10ths. Can someone post a section of a program that works or simply tell me what I'm doing wrong.

[txcncman]

Does the spindle speed up or slow down when X changes? What are you using for the max RPM setting? Do you have any inverse functions set on?

[BetaBob]

Yes the spindle increases speed as the tool tip gets closer to spindle center, but some where around .750 the feed slows to a crawl and the rpm increase at a very slow pace. Max RPM is set at 2000, but the spindle speed when it slows is only around 1100.

[txcncman]

Can you manually run the spindle at faster than 1100 RPM? Does this lathe have high and low gears?

[BetaBob]

The lathe will run at RPMs higher than 1100. I can do a face operation without CSS at any speed, and it works fine. Yes it has 3 gears.

[txcncman]

If you are running M41, maybe you are maxing out the RPM before CSS is reached.

[BetaBob]

Gear selection is manual on this machie, so we are not using a M41. It is in high gear 90% of the time unless we are turning something really big at a low RPM that needs lots of torgue.

The max RPM of the mcahine is 2000. It slows to a crawl in the range of 800 to 1000. No errors, nothing. If I set the max RPM to 800 it will feed just fine, but the finish is not what I need.

I don't have this issue on either of my Mazaks.

[jagardner4]

If this is a DynaPath branded lathe (you didn't say), then txcncman is probably on the right track.

Yes, the gear shift is manual, but there is no switch to tell the control which gear the spindle is in, so the operator has to tell the control by programming an M41, M42 or M43. Usually this would be entered as an MDI event after manually changing the shifter. If the control thinks its in a different gear than the one manually selected, it will get the analog command voltage curve wrong. This is the analog +/- 10 V command to the spindle inverter.

[BetaBob]

No it is not a Dynapath lathe. It's a Graziano ( I know, a what) , that was fitted the the 50 control. There is a switch that detects the change of the gear position. No matter what gear I'm in it runs the prgrammed speed, unless of course you max out the RPM on the spindle control.

I was hoping someone could post a program that they use on a similar control so that I could compare to the one I prepared.

I called Dynapath yesterday and they had no suggestions, but are looking into it.

[txcncman]

Had a YAM years ago that would not feed correctly that was related to spindle speed. The spindle would run the correct RPM, but the control itself would lose its mind and feed erratically.