Hello Everybody. 

I'm just looking for some insight into tuning my Dyn4 Servo drives.  Dmm's autotune software doesn't seem to do my mill justice.  I'm running DYN4 drives and 86M DHT 750W servos on an old Bridgeport R2E3 CNC with Mach3 as the control.  I know there are guys out there running this exact combo.  Wondering what you guys are putting in for gain settings in your servo drive tuning software and what your max speeds and acceleration settings are in Mach3.   

I want this mill to perform better than original and believe it will with the right settings.

I might be able to help a bit, I've been beating my head on the DMM servo settings in Mach4 and their auto-tune settings on a panel router.
What sort of performance issues are you seeing or not seeing? I'm asking this as there are a bunch of tricks for working around the auto-tune to wring the most out of your unit.

I have for the most part been able to get the machine running decently. The main issue I was having was kernel speed and pulse resolution through my parallel port.  I discovered that you can run the servos at significantly lower than the 2000pulses/rev that DMM says.  You can actually set your gearNum setting to as low as 125, resulting in 500pulse/rev.  I ended up running 1000pulses/rev. 

I still get the occasional alarm on the Z axis, generally on the deceleration of a rapid move.  Haven't checked what alarm it is but I'm pretty sure it's a positional error and inertia related. 

As it stands the machine operates at the same rapid speeds as the original Bridgeport control but is now much more user friendly. Not sure about max cut pressure either.  I was hoping to have the machine faster and more powerful than original. Didn't really get it, but am glad to have an operational machine. 

You should be able to play with the acceleration for the motor in Mach for the Z axis to reduce the 'shock' load that the servo sees on starts and stops.
At least you can in Mach4.