Diodes or Relays to protect electronics from backfeed from steppers

[iraywest]

I have looked and cannot find any threads on this topic. Any direction and/or advice is appreciated.

Has anyone considered using mechanical relays or diodes to protect the electronics from the steppers being manually turned and creating electricity that could fry the drivers? I would like to put hand wheels on my mill so I can do some limited manual work but am concerned with the feedback to the electronics. My first instinct was to put mechanical relays in the circuits between the motors and the drivers that would only engage if the electronics are on but mechanical relays are bulky and mechanical contacts wear out. Second thought was diodes but as I am not an electronics wizz, I don't know if there are issues with this. Advise/experience is appreciated.

Thanks,
Ray

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[A_Camera]

The better drivers have reverse current protection built in but if you are not sure you can always add even simple mechanical flip switches. One two pole switch for each stepper is all you need since it is enough to disconnect one wire of each winding of the stepper.

[Al_The_Man]

Your drives should have some BEMF protection built in, the amount of generated BEMF by manually turning the HW I would think would not have any impact on the drives due to the anticipated low rpm in turning manually, unless a large degree of gearing is in place between HW and stepper.
Al.

[cjmerlincnc]

Don't use energised relays to connect the stepper to the drives, if at any time the relay faults and disconnects the steppers it'll destroy the drivers.