Need Help!- TRON with 2.0Nm Steppers

[George]

Some questions I would be grateful of an answer if you can help.

1) I propose to use Kelling Technology KL23HM276-30-8B Steppers with my Tron Router table. These are rated at 2Nm when wired in Bipolar Serial or parallel mode. Will thes be powerfull enough to drive the main axis.

2) Whats the advantage over unipolar, Bipolar serial or bipolar parallel methods of driving these steppers.

3) The main axis uses 2 steppers to drive it, one left and one right. Is it absolutly necessary to physically connet the steppers together at the non drive end with a 'toothed belt' In other words is the sychronisation of both steppers all that important.

4) Steppers are 'dual shaft' is there any advantage of using encoders for each of the steppers.

5) What is the most efficient method of drive, i.e full step or half step or wave.

5) Anyone using the 'Delagrange Technology' drive electronics.

I would be very grateful for some answers.

Thanks

George

[ger21]

1) Not sure

2)With an 8 wire motor, bipolar give more torque, with Parallel capable of much higher speeds.

3) If you use mach3, they can be synced with the software (Slave function) Not necessary to use a belt. Imo.

4) Nope, there's really no way to do anything with the encoders.

5) Neither. You want a microstepping drive for smoother operation. Full step is better at higher speeds, though. Gecko drives are microstepping drives that morph to full step drives at higher rpm's, to give the best of both worlds.

6) never used them.

[George]

Originally Posted by ger21 1) Not sure 2)With an 8 wire motor, bipolar give more torque, with Parallel capable of much higher speeds. 3) If you use mach3, they can be synced with the software (Slave function) Not necessary to use a belt. Imo. 4) Nope, there's really no way to do anything with the encoders. 5) Neither. You want a microstepping drive for smoother operation. Full step is better at higher speeds, though. Gecko drives are microstepping drives that morph to full step drives at higher rpm's, to give the best of both worlds. 6) never used them.

Many thanks for your input Gerry.
I'm not sure whether my Delagrange gives me the option of Micro-step, I'll check it out.

George

[YZF]

Hi,

In a sense, serial or parallel configurations let you trade off voltage and current. A parallel configuration will require twice the current to get the same torque... With a given bus voltage and a current motor drive the back emf generated in the motor will limit your maximum speed which is why you can go faster with the parallel configuration. So the choice of serial or parallel depends on your drive electronics, the motor, how much torque you need and how fast you want to go. If you post specs for your drivers I can show you how to work this out.

Unipolar is a tradeoff between ease of driving and performance. It is much simpler to build a constant voltage unipolar drive (just 4 transistors) but the performance is poor...

As to whether or not 2Nm is sufficient you need to look at your accelerations (F=ma), your cutting force and friction. I'm assuming the motor is connected to the load via a screw. The pitch of the screw determines how much force you get for a given torque (minus friction loss). I'm not familiar with this table but if you give some details about the drive mechanism I can give you a guesstimate

In theory having encoders on the shaft would allow you to detect and compensate for missing steps on the steppers. There are motor drives that can take advantage of this configuration. With a high enough resolution you can also drive the stepper as if it was a brushless servo motor - again you'd need some specialized drives that can do that.

If you want to read a bit more about microstepping and stepper motors in general this is an excellant resource: http://www.cs.uiowa.edu/~jones/step/micro.html

Guy