Weird rotary axis movement

Hello, we have a machine with a rotary axis, in some corners the cutter does not reach the corner completely and makes a rapid movement on the rotary axis. I tried to reduce the error with G64 but lowering the P value makes it worse.

Machine is running analog servos, old yellow cap fanuc.

The error is consistent int the same place.
Attached a pic.

Thanks
 

Could you post the G-code that is giving the error? Not necessarily the the entire G-code program. Especially if the program is large. Just a snippet that includes at least a few lines before the error, and a few lines after, so we might be able to test and reproduce the error. It's a little hard to see and understand what is going on just from your image.

If I remember right, linuxcnc doesn't do synchronized motion on rotary axis.
Maybe wrong term but feeds,speeds and acceleration is determined by x,y,z only and the rotary axis will do the best it can. When it can't keep up this in the figure happens.
One usually uses the inverse time feed specification G93, and calculate the time needed for the movement in the CAM post-processor.
There are converters on "the web" that can translate G code to G93.

It isn't that Linuxcnc doesn't do sychronized motion with rotoary axis. Rotary axis are sychronized just fine with linear. The problem is the incompatability of linear feed rate units with rotary feed rate units. The result is often (especially with inches) unexpectedly slow movements when a rotary move is mixed with a linear one. The problem is actually a G-code limitation, rather than a Linuxcnc one. For example you are milling along at F20 inches/min then you throw in a 40 degree move with the rotary. The rotary move is going to take 2 minutes to comple because of the F20, if the same line also includes a 1 inch move, the linear move will be limited to 0.5ipm so that it takes the same 2 minutes to complete. This is where the invers time mode comes to the rescue. it has no unit of measure involved just time. So if you want your 40deg 1inch combined move to move so that the linear component still moves at 20ipm you would specify F code on the line as 1/t or in this case 1/0.05min. or F20.0

Yeah I didn't remember that right. Then I wonder if that's the problem here.

Look at this, it might help.