Hello Tweakie and RICH. Per your suggestions I have included the .xml file that I am using.
I do not know how to set the motor current with Mach3. I presume you (Tweakie) are asking me to set it directly with the CNC driver. I have attached a picture showing what my controller board for 1 axis looks like (there are 3). I have already tried tuning my motor to run painfully slow or blazing fast. I saw very little change in problem for either speed. Slowing down the motor did not improve the situation. I also made sure to use slow feed rates for the G01 commands to Z axis. This had no effect at all.
I would really like to correct my problem with software if possible, however, I suspect that I have a bigger problem; hardware issues.
My driver boards are a simple cheap boards (picture). I see the name "TONSEN CNC", but I don't know anything else about them. My system is a cheapy CNC from China (you get what you pay for). I took the board off and found that the IC driving the motors is P/N A3977SEDT. I looked it up on Digikey.com and found that it is indeed a stepper motor driver chip capable of driving up to 2.5 amps. There are no adjustments on these boards, so I cannot set the current manually. I see a large 3 watt resistor, but I dare not change it out for a lower value.
I honestly believe that my problem lies with these cheap CNC driver boards (it's a red flag that I can't give you a part number). The X&Y axis' work well, and they use larger motors (Vexta 103H7124-1142, 2.4 x 2.4 inches). The Z-axis motor is slightly smaller (Vexta C8513-9012K, 1.7 x 1.7 inches), but seems appropriately sized for the job. Listening to this motor in action, it does not seem to be struggling with the given load.
Sorry, but I can't identify the motors any better than to provide the part number. I don't know where to find where these motors came from (aside from knowing they came from China). There is no "Vexta" website breaking down these part numbers. The same is true of the driver boards; Another "red flag".
I am willing to replace the motors and motor drivers, but I need a recommendation. For example, do I need a "4th" axis to activate the spindle motor, or can I use my existing breakout board to do that? What do other users do to turn on the spindle? I need to make sure that whatever driver/motor combination I get is compatible with Mach3. I currently use the LPT port to drive my controller. Should I get a CNC driver kit that supports encoders? I'm not sure if Mach3 can use them.
One last thing, I know Mach 3 is open loop. Does Mach 4 support closed loop operation using encoders?
Thank you very much for taking the time to help.
Best regards, Richard V