Re-Building Suregrave CNC

[PeterC]

Hello all,

Just posted my first update video. The core of the electronics are done, still plenty to do!



All thoughts, comments or suggestions gratefully received!

Peter

[Clive S]

Hello all,

Just posted my first update video. The core of the electronics are done, still plenty to do!

https://www.youtube.com/watch?v=AMDI7uFNv0U

All thoughts, comments or suggestions gratefully received!

Peter

You are doing a nice job and excellent vid.

[JAZZCNC]

Word of caution with using 48V with drives rated at 50V, esp the DM542 clones which don't tolerate over-voltage well.

Steppers generate electricity when de-accelerating and will send this back to the drives and PSU so with drives rated at 50V Max and 48V PSU the back EMF can easily exceed and damage the drives.
Also with 48V if your incoming AC electricity fluctuates like most domestic supplies do then you can easily exceed the drive's Max rating as the Output is relative to the Input voltage unless regulated and damage them or at best shorten their life.
Another issue with back EMF is that if your PSU's are the regulated type, which the video doesn't show so can't tell, the back EMF can cause them to shut down to protect themselves which is the last thing you need on a CNC machine so regulated PSU is not recommended. The best type of PSU is an Unregulated one and the best type for CNC is a toroidal supply as it absorbs back-EMF much better.

When sizing PSU you really need to leave a 10% safety margin and with 48V you are too close for comfort so I would advise you to keep the speeds and acceleration down.

[dazp1976]

Word of caution with using 48V with drives rated at 50V, esp the DM542 clones which don't tolerate over-voltage well..

Im with Jazz on this.
I'd rather get a 48v that's adjustable and drop it to 45v.
I'd never go back to the 50v drives since using the DM860T.