6 wire motor options

[Ross77]

I have a small engraving machine that I'm hoping to get up and running to cut some pcbs. the current set up uses 6 wire steppers running of a unipolar drive. I can't easily tap into the divers so looking to replace them with new drivers.

I have looked around and I can run them as 4wire on a bipolar drive but will either have to lose speed or torque depending on which coil I use. existing PSU is 50v and my drives are 50v so not much option to up the voltage

Is it worth driving the old motors in bipolar or will I lose to much speed or power?

Ultimately I will upgrade the motors etc. but I could do with a quick fix to get it working to finish some other projects moving.

[Gary]

If the motors worked ok on the machine as unipolar, then using a bipolar driver will give you better performance.
going full coil will give you more torque and going half coil will give you faster speeds at the same time sacrificing torque at the lower speeds.
its an engraving machine, so its likely whatever way you connect it torque will not be an issue?

[Ross77]

Thanks Gary
I was going to use the M542-G's that I got off you a while ago...... Is it possible to have relays switching between full and half coil for rapids or will it damage the drives?

I'm going to use LinuxCNC to control it so should be possible to set up an output. (still learning)
Thanks

[Gary]

That will kill the drivers and if it didn't would also cause positional errors.
I would not try and over think this, going full coil will most likely give you better performance than what the machine had originally.
Try it out in both configurations and see what performs better for you.

[Ross77]

Thanks Gary

Always over thinking things :0)

I was looking to use this as bit of a test bed to learn Linux as well and it seemed like a good idea. As long as it will mill pcbs then I'll be happy.

[Ross77]

Had another look at the machine today and noticed that the stepper is 1.65v and 4.7A, will it matter that the drivers are only 4.2A peak?

I bought the Gerber engraver and 3 vinyl plotters as a job lot and they all the same make of stepper. I have another motor that is higher voltage and lower current, would that work better?