Z axis diving

On temperature, the rule I’ve seen tossed around on the forum is to keep the motors below 50C. Temperatures above 50C start to risk the PLA plastic. An IR thermometer can be inexpensive and give you a real reading of the temperature of your stepper. If you have the current at the default V1 setting, and reasonable steppers, you should not see temperatures above 50C.

It is exceedingly rare for a stepper motor to go bad. In the hundreds of posts where a bad stepper was a possibility for an issue, I can only remember two bad steppers. So, if you’ve had a stepper go bad, you need to carefully consider the current setting and stepper you are using.

A 2.2Kw spindle has to be heavy. If you have not already done it, consider going with a 1-start or 2-start lead screw. The V1 specified 4-start lead screw moves at 8mm per turn. A 2-start lead screw moves at 4mm per turn, so it doubles the torque. A 1-start lead screw moves at 2 mm a turn, so it quadruples the torque. Going to an alternate lead screw with reduce your max feedrate and requires you to adjust steps/mm. Also, if there is some other underlying issue causing your problem, an alternate lead screw could hide the problem, rather than just fix the issue.

The behavior you are experiencing is similar to what happened when Fusion 360 removed the rapids for non-paid users, so if you are using the personal/free version, limiting rapids does nothing. The recommended post processor for Fusion 360 can be found here, and it makes provisions for no rapids.

If you have not done so already, I recommend limiting the feedrate for Z in the firmware. You can use M203 to set the value, followed by an M500 to save the setting. *Note that this setting is in mm/sec, not mm/min. The V1 recommendation for Z on the Primo is 480 mm/min, so that would be 8 mm/sec.