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Mr.Ben
07-02-2019, 05:16 PM
Hi, all.
Finished building a new bench top router and am having the following problem. When I power down, the Z axis drops until it hits something. The Z has 25mm Hiwin rails and carriages, and weighs about 35 lbs. It is powered by a Clear path nema23 driving a 1605 x 350 rolled thread ball screw, supported at both ends.
What is the best option for stopping this? I hate to add a spring to the side as this would eat up X travel.
If I turn off the motor enable power it drops very slowly, but killing the power to motor allows it to drop fast enough to hurt you if you got in the way. I gotta fix this. Your ideas are welcome.

Ben

Sam0117
07-02-2019, 10:34 PM
Hi Mr.ben I have infeeling that your stepper motor is faulty or wired wrong? When a stepped motor has its pairs correct the motor wonít turn unless it has a signal to move, so when you power off you shouldnít have the z axis drop, sorry I can be more helpful but Iím confident you have a problem either with the stepper motor or how itís been wired up

Hope this helps 👍🏼

Clive S
07-02-2019, 11:03 PM
Hi Mr.ben I have infeeling that your stepper motor is faulty or wired wrong? When a stepped motor has its pairs correct the motor wonít turn unless it has a signal to move, so when you power off you shouldnít have the z axis drop, sorry I can be more helpful but Iím confident you have a problem either with the stepper motor or how itís been wired up

Hope this helps 👍🏼

This statement is incorrect. When a stepper is not energised it can free wheel and will when the Z is heavy. Some machines have an electric brake on the Z motor for that reason.

Ger21
08-02-2019, 01:50 AM
He's using a servo, so it's not relevant.

What you really need is a servo with a brake.

johnsattuk
08-02-2019, 10:12 AM
As pics