The code below - genrated by hole pocketing of my CAM prog - causes my Z axis servo to die by following error on line N190. The material machined is soft plastic and this certainly is not a problem of lack of power in the Z motor.  On several occasions the latest Mach3 version xx.038 stalled and reported of an error on in the R I J values but the simulation goes fine though. G91.1 is used for I,J.

....
N90 (BEGIN - First Tool Macro)
N100 M901
N110 M6 T2
N120 M904
N130 G00 X175.2191 Y54.7403
N140 G00 Z5.0000
N150 M03 S16000
N160 (END - First Tool Macro)
N170 G01 Z-0.3650 F1000.0
N180 G17
N190 G03 X175.2602 Y55.0000 Z-7.0000 I-0.8691 J0.2597 F2600.0
.....

If I change the z movement to the previous line it works, like this:

...
N170 G01 Z-0.3650 F1000.0
N180 G17 Z-7
N190 G03 X175.2602 Y55.0000 I-0.8691 J0.2597 F2600.0
...

How Mach handles line N190 is what is of interest here I guess.

I think there is a problem with 3 axis circular interpolation if your Z axis is a lot slower than the other axis, is that the case with yours?
I think Ray L had this issue with the Z axis on his mill as he had the knee as the Z and its rapids were a lot slower than the other axis, not sure if he found a work around but seem to remember something about exact stop so might be worth trying a G61 before that move.
This should be sorted in Rev4 when it comes out.
Hood

I think there is a problem with 3 axis circular interpolation if your Z axis is a lot slower than the other axis, is that the case with yours?
I think Ray L had this issue with the Z axis on his mill as he had the knee as the Z and its rapids were a lot slower than the other axis, not sure if he found a work around but seem to remember something about exact stop so might be worth trying a G61 before that move.
This should be sorted in Rev4 when it comes out.
Hood

OK, thanks, have to check that. I'm using the same servo motor size for Z & X & Y with same gear ratio, Z having the lightest load so I doubt this could be an acceleration/speed/power issue. I'll check what Mecsoft has to say about this.