Triac VMC Servo // Z-Axis Dropping on power off

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danielbriggs
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Joined: Sat 14 Jan , 2012 2:41 am

Triac VMC Servo // Z-Axis Dropping on power off

Post by danielbriggs » Fri 22 Jun , 2018 1:42 am

Hi all,
I'm having an issue where the Z axis on my yr2000 Triac VMC - Servo (Baldor Servo + drives) 1ph... will drop the Z axis on power off or e-stop. It only does it sometimes, but when it doesn't... touching the head with fingertip pressure will cause the head to drop full [rotates ball screw] until it's at the end of the travel.

This machine has just been started to be converted; so I've rewired a few bits.
So... I understand why servos do this... (as opposed to steppers // holding torque etc.). However I am under the impression Triac's do no have a servo brake, or a counterbalance fitted. So was looking at do I need to fit a gas strut to stop my Z-axis dropping.

BUT: Why should I have to do this? I assume the machine worked perfectly without this, with the original DOS setup. What possible wiring could I have changed which now makes the Z-axis drop on power off? Is there anything I'm missing?
There were no brake / regen resistors fitted previously to the drives. Do I need to add these in, or are they only for decelerating at high speeds?

Also, does anyone have any advice on tuning the Baldor servo drives? The defaults were well off. Just wondered if anyone had any tip or direction on this.

All the best,
Dan

Martin
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Re: Triac VMC Servo // Z-Axis Dropping on power off

Post by Martin » Sat 23 Jun , 2018 9:23 am

It could be as simple as adjusting the Jib strip. The procedure should be in the manual.

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