I recently received one of the new Leadshine DM556,
http://www.americanmotiontech.com/pr...ries/DM556.htm
DSP based stepper motors from American Motion Technology. I'm designing a high end telescope mount and have been searching for an extremely smooth stepper driver to compliment the mount.
My test bed for stepper drivers is a 2'x4' 80/20 CNC router. Important features for me are:
1. Smoothness of motion. When your tracking stars through mega-buck telescopes, the motion has to be silky servo-like smooth.
2. Heat. I've tested a lot of steppers and am surprised at the difference the driver topology can make in how much heat is absorbed by the motor. As a high end mount with the motors exposed, I don't want to be burning my customers.
3. Noise. Nobody likes having a peaceful night of astronomy ruined buy buzzing motors.
4. Speed. Speed and steppers are often enemy's but in my application, I need a high dynamic range stepper driver so that it doesn't take all night to get to another astronomical object.
How the Leadshine DM556 rates on my list of important features:
1. Smoothness of motion: With stepping rates all the way down to 256:1 the microstepping feature is certainly adequate. But large number of microstepps does not necessarily translate to true smooth motion. The great thing about the DM556 is the tuning software that is included with controller. It allows you to have very fine control over the way the motor is handled by the controller. This lets you tune your controller to your motor, essentially eliminating resonance.
2. Heat: I have been pleasantly surprised at how little motor heating occurs with the DM556. It has been my experience that you can either have a cool motor, or a cool controller but not both. Well, so far I have both with the DM556. I don't know how it does it, but I like it.
3. Noise: Some of the unipolar choppers that I've tried make a constant hum while the motor is still. This is unacceptable for my application. The DM556 is 100% silent, and even in motion is much quieter than many other drives I've used.
6. Speed: High speed for my application requires zero loss of steps, smooth motion, and zero resonance. Anything less and you'll have megabuck telescopes being thrown out of optical alignment. My maximum speed on the mount is 1200 RPM. I have only been able to go up to 600 RPM with my test mule router so far. At 600 RPM the motion is very servo like and hauls my 80/20 router around at 150 IPM, I'll be working to test out the DM556 at faster speeds in the future.
So far I'm very impressed with the DM556. The software tuning of the motors allows excellent performance over a wide range of motors and applications. The smooth DSP controlled performance of the drive is the best I've found yet (at any price) in a stepper driver.
For reference my test setup was a
www.cncrouterparts.com based 80/20 4'x2' router with an ACME 2 start 8 TPI (4 effective) thread. My motors are Hobby CNC 425 oz/in run in bi-polar mode. My power supply is 48volts at sufficient amps.
Previous to using the DM556 I was using a HCNCPro uni-polar 3 amp driver. Maximum speed was 50IPM, using the same current settings I'm now running at 150IPM (in bi-polar series) with the DM556.
-Jim