Problem with BNC Miyano Barfeeder lathe.

[Tonenc]

We have an old BNC 10T barfeed lathe,it has started moving around dimention wise,we have replaced the x-axis encoder but it still moving all over the place,backlash has been adjusted,seems to be about 10 microns every cycle,checked the program a 1000 times,pretty sure its not compounding,could this be a main board prob?

[Tonenc]

Have since found a quick fix,just a g28 u0 w0 at the end of the cycle has fixed it for the mean time.

[Gunner]

If G28 U0 W0 at the end of the cycle cured the problem it sounds like the original problem exists in the program. G28 U0 W0 sends your x and z axis back to their home position before you start your next cycle thus reorienting your tooling. Since the G28 cured the problem my guess would be you are programming incrementally (U and W) vs absolute (X and Z). Try programming in absolute to see if it is actually a machine issue. If the program runs fine and dimensions hold then I would take a closer look at the program on the machine you have the issue with.

[Tonenc]

I thought when it started doing it that it might be something to do with the program,but its actualy an 8 year old program that has run fine the whole time,it does have a lot of incremental moves in it with a lot of canned cycle threading,we did have trouble on the machine next to it also,which now will not accept a g76 threading cycle at all,i'm thinking its a board prob or something,but i will prob end up taking all the incremental moves out alltogether,....thanks for the reply.