J325 Spindle repeatability

[ramsey321]

I just got my 325 Tree fired up and I made a few projects without any issues but now I am having a problem with repeatability with my Z motion. It seems the spindle wont orient to the same spot when running a program or when setting a tool hieght. It varys between .010" to .020" if not more. What could be causing this issue?

[NewLondon]

I'm having a similar issue with our 325, was advised to tune Zaxis servo. Still not quite sure what that entails...

Marshall

[underthetire]

If it varies with no alarms, check the timing belt and pulleys. Also check for heat on the quill. It's common to have repeatability issues if the spindle bearings are going. It heats the quill up, sticking it in the bore. Also check to see how much the spindle pushes out when you hit tool unclamp.

[Toolbit]

I had that problem with a Tree Millienium. Turned out to be the z-axis ball screw preload nut had loosen. You will need to lift the servo motor and check.

[Toolbit]

Oh, I should have said that the nut that will be loose is under the timing belt pulley for the z-axis ball screw. You still have to loosen the servo motor so you can get the timing belt and pulley off to check the nut.

[cncserveng]

errr..... pardon my ignorance, but are we talking about spindle orientation; "keylock" position we used to call it or, Z axis positioning for a tool change ?

If its orientation; could be the spindle encoder, orientation sensor, cable, timing belt etc;

If its Z axis positioning; could be pulley slippage, belt, motor encoder, tool change parameter etc;