daewoo ace h50s - fanuc 16-m - B AXIS not return to zero..

[shimmwagen]

so new problem today. started machining a part yesterday. noticed that table was off a couple of degrees cutting a taper over the 12" length i was cutting, around .06" difference from front to back. switched pallets and dialed in other side and it was fine. took off pallet that was 'out', cleaned bottom, put back in and dialed it up and all seemed good. go to run program this morning and table 'out' again. did a pallet change and measured and all good. ran program, cut b0 side fine, rotate to b270 and again i'm getting a taper, dial table and it's way out. do a few rotations in mdi and constantly out of zero. turn off/on, home everything, do pallet change and table is fine. made a mark on the bottom of pallet where it rotates and marked zero. rotate 90 degree and table out again, brought back to zero, mark lined up but dialing in table its way out again! checked in x and z direction and both ways the table is not square. any thoughts???

[shimmwagen]

marked the base and pallet at zero to try and see what's going on. when i rotate and bring back to zero the line is out and table is not square. looked closer at pallet change and when new pallet comes in the 'base' shifts back to zero, repeat B movement and line is out again. bring in other pallet and it shifts back to position. something lose under the base? as it's 1 degree increment table guessing it's gears that hold it all in position?

[dhardt]

An index table is purposely built with a lot of backlash, because the curvic teeth lock together and give the accuracy.

If the locked position is "all over the place" the problem is the curvic is moving. (even if it were crashed into a different position, it would still repeatable hold that exact location...unless the curvic were loose and moving around.)