Y axis Drift in rotary carving

I did my first rotary carving yesterday, and almost everything came out the way I expected except for the left-right meeting on the "back" of the carving.

Here is the design file in Project Designer 2.007 build 11929
Front
Attachment 70192
and back
Attachment 70193

and here is how it carved:
Attachment 70194
The front is fine, 180 degrees through the carving, its when it gets to the wrapped portion that the carving shows the Y axis drifted as it turned on the X axis:
Attachment 70195Attachment 70196
any suggestions on what could have caused this?

Richard

Did you do the set up procedure on the jig where you move the tab that sticks down on the opposite side from the keypad ?
the bit should line up on the line in both plates…if not u need to move the tab and check again.

If that checks out good I would look at the mpc and make the part off bigger so the bit doesn't have to plunge as deep on the ends


Brent

Lined up the bit with the grooves on the frame (had to adjust the off-keypad side a fraction) and ran the alignment 3 times to make sure it was getting good rotary offsets. Since the displacement is over the whole length of the carving, I don't think the issue is the part off (which was set to .5 in)

I find that to be a very curious behavior. The y drift on a flat board seems always to be in jumps caused by a gear or belt slip. Since that seems not to be the case here, the dowel must have been slowly moving sideways. Is that possible? Could the jig have moved? Check the squaring plate to see if it is loose.

Looking more closely at the discontinuity, it seems to be related to the diameter of the particular section of the tower... which leads me to suspect a rendering error, possibly in writing to the memory card. I'll try another card, and maybe a reformatted one.
Attachment 70199

I've had the same problem in two sided carves, sound like the z encoder. Dust. Anatomy of the Z Encoder 101.pdf

It could be the encoder. (It would be the y encoder and y encoder problems seem rare.) There are many new variables with the rotary jig. If the jig is not to blame, maybe the y encoder should get a check.

Quote:

---

Originally Posted by Baron Richard

Looking more closely at the discontinuity, it seems to be related to the diameter of the particular section of the tower... which leads me to suspect a rendering error, possibly in writing to the memory card. I'll try another card, and maybe a reformatted one.
Attachment 70199

---

I have tweaked patterns before by making them a little larger and moving the angle or tilt to get the seam to line up.
Even when you do that the part off is a straight line with no off-set as yours seems to be.

Be sure you have the bit optimization set to "Best", and uncheck the "Floor Feather" check box. Looking at your screen capture, none of these settings have been selected and are essential. They are also outlined in the Carvewright video. This may help.

The calibration would have no effect on this because that is for X and this problem is Y. A dull bit might cause it to drift. If you have the carve set to normal, it may be taking too big a bite and pulling the Y truck along on the climb cut. With the deep rotary carves, take small bites - use at least Best if not optimal.
Clint