[plasticbaldy]

Please excuse my lack of knowldege here. I started wading through all the threads but just got dizzy.
I have a 3 axis CNC router that utilizes 3 Gecko G201 Drivers.
It was built with chain drives on X & Y.
I'm replacing the chains with ballscrews and would like to have 2 ballscrews on X.
Can I just wire another G201 in parallel to the existing G201 X to achieve this ?
The previous X stepper was a Superior Electric Slo, Syn, Type M092-FD09, 200 oz/in, 200 steps/rev, 2.5V, 4.6A, DC and it coped reasonably well.
I'm guessing that I need 2 matching steppers for my 2 X ballscrews & I'm OK with that.
I would like some more speed so I'd be pleased if the 2 Steppers I buy would be of similar or better performance each to the Superior Electric.
If my assumptions are correct then can somebody please recommend some options for the motors.
It would be convenient if the motor flange dimensions and Motor Diameter were maximum 81mm (3 3/16") but if price or perfomance considerations dictate then I could cope with larger.
If there are any wiring requirements other than parallel wiring the second G201 then please guide me.
Thanks for your patience.

[doorknob]

The typically-recommended practice for driving two motors on the same axis is to treat the second X-axis motor as if it were a separate axis, and then slave it to the first X-axis motor within the software (such as Mach3).

While I believe you could achieve a similar result by paralleling the driver inputs by feeding the same step and direction signals to both axes, I have not actually done that, and there may be reasons why that is not the best approach. For example, driving both motors with the same signals does not permit any adjustment for possible misalignment or out-of-sync condition between the two motors, whereas treating them as separate axes permits the software to correct any such condition.

As far as suggesting suitable motors, I don't have sufficient experience with that size machine in order to guide you, and so perhaps someone else will jump in and provide some info.

[plasticbaldy]

I'm planning to use 2 identical Stepper motors. If they go out of alignment then I'd turn off the driver & manually rotate one ballscrew to correct it then restart. Is there another reason why I should treat the second driver as a slaved separate axis ?
Is there some feedback facility between the motors and Mach 3 that would automatically correct misalignment or out of synch condition ?

[doorknob]

The following discussion from page 4-15 of the Mach3 manual "Mach3 CNC Controller Software Installation and Configuration" at http://www.machsupport.com/docs/Mach...all_Config.pdf provides a useful rationale:

4.5.5.5 Slaving

On a gantry type mill or router where the two “legs” of the gantry are driven by separate motors, then each motor should be driven by its own axis. For example, if the gantry moves in the Y direction, then axis A should be defined as a linear (i.e. non-rotational) axis and A should be slaved to Y – see Chapter
5 on Configuring Mach3 for details.

Both axes should have Limit and Home switches. In normal use, both Y and A will be sent exactly the same step and direction commands by Mach3. When a Reference operation is performed, then the axes will run together until the final part of referencing, which is moving just off the Home switches. Here they will move so that each stops the same distance off its own switch. Referencing will therefore correct any racking (i.e. out of squareness) of the gantry, which might have occurred when the machine was switched off or because of lost steps.

[plasticbaldy]

Very helpful Doorknob. Thank you so much.
:wave:

[plasticbaldy]

OK. I've slaved A to X (master) and changed A to linear drive in 'General Logic Configurations' and I now have both X and A functioning.
Is there anything else I need to do ?
I haven't worked out how to setup Home switches for X & A yet. I was going to mark my X & A Linear Bearing shafts with a scribe and manually rotate either X or A ballscrew if X & A got out of synch as a tempoprary fix till I get the Home Switches working.
BUT
Do I need to configure Stepper Motor A to the same speed and acceleration as X in 'Motor Tuning' ? I have identical Stepper motors on X & A.

[doorknob]

Do I need to configure Stepper Motor A to the same speed and acceleration as X in 'Motor Tuning' ? I have identical Stepper motors on X & A.

I believe so.

[ger21]

Yes, both must have the same settings in motor tuning.

[plasticbaldy]

Thank you. I appreciate the help.

- A slaved to X.
- A in Linear mode
- Identical Stepper motors for X & A both tuned to the same 'steps per', speed & acceleration.

Are there any other changes to settings or configurations that I have to make to now safely operate my CNC router table with the 2 motors on X drives ?