Re: Looking to retrofit a Supermax YCM-40, how do I figure out what I need
I think a 400W servo on the Z and 750W on the X&Y would be more than enough on that machine.
Your machine is about the same size as mine, with a 10x54 table. My X&Y brushed servos are 32 in/lb (3.61Nm) rated torque, rated at about 750W. My Z axis motor is actually a NEMA 34 stepper, but it runs as an analog servo, the controller thinks it's running an analog servo motor, this is a special and very rare case. I suspect your machine weighs around 3500 lb as mine does, pretty sure they are the same base frame size.
Having said that, modern AC servos are the way to go. My preference is Automation Direct SureServo2 (Delta) or LS Servo line. I have used both on projects with good results. Both have excellent documentation, and local (USA) support.
https://www.automationdirect.com/selectors/sureservo2
https://www.automationdirect.com/selectors/ls-servo
While I have used both ClearPath and DMM servos on projects, I no longer recommend them. I'm not going to further explain that statement.
The only reason I am using DC servos on my machine is that they are the original motors and have been working fine for the last 35 years and I saw no reason to change them out when I did the controls upgrade. If one fails, I will be going with the SureServo2 750W units. No point in installing 50 year old technology when you need to change out the motors anyway.
A brake is not needed on the Z. My rapid feed rates will easily hit over 200 IPM, and most likely around 300 IPM. But I limit it to 100 IPM rapids because the machine is not bolted to the floor and it actually will move the machine at high feed rates. Nm does not translate to IPM, they are not really related. Acceleration is a function of torque, but once up to speed it requires very little torque to maintain the speed, just friction losses plus tool load.
Acorn is fine, so is Linux CNC, or Mach4, or any number of other of other systems out there. The servo systems I linked to above are compatible with virtually any system. Acorn is an open loop system as is Mach4, so the loop would be closed at the drive, this works fine but my preference is to close the loop at the controller using analog control and 1 micron magnetic linear scales on the axes. This pretty much automatically compensates for any backlash or ballscrew error, but there is no substitute for a mechanically tight machine. I typically see accuracy of +/- 0.0002'' or better with my machine.
Jim Dawson
Sandy, Oregon, USA