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Why you should power off when unattended

Posted by frankvdh 
Why you should power off when unattended
December 19, 2020 04:06PM


This was the A4988 Z stepper driver on my laser cutter as I found it after cutting. My control board is, as recommended by the manufacturer, mounted vertically on the gantry, not covered at all. When I replaced this stepper driver, everything worked as usual, so no fuses were blown.

NB that the Z stepper is only used for focussing before cutting, not at all during the cutting operation. So I guess that this could happen any time the board is powered up.

Apologies for the blurry photos.
Re: Why you should power off when unattended
December 19, 2020 09:12PM
I think those modules are poorly engineered. They can't dissipate enough heat because of the small size of the circuit board. You can get better controllers that don't use modular motor drivers...


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Why you should power off when unattended
December 20, 2020 03:02AM
Yeah, but this failure wasn't due to poor heat dissipation. There had to be a pretty good short circuit to peel up a layer of the board. And, as I said, this was the Z stepper on a laser cutter, so not actually doing any work.
Re: Why you should power off when unattended
April 23, 2021 01:11AM
I'm pretty sure those kind of stepper drivers run at constant current regardless of whether the motor is moving or not. With newer Trinamic drivers, current can be controlled by software, and set to a lower value when holding still. I always stick heatsinks on my stepper drivers regardless. And a fan for the ones on my CNC, which are that old style, and running NEMA23 motors which they're not really designed for. They used to get pretty darn hot with heatsinks alone, but only slightly warm to the touch with the fan. I'm sure they would have died with no heatsink or fan smiling smiley
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