Printed motor mount warp

Just wanted to share a couple of pictures of a printed motor mount that I just replaced in my printer.

It was printed in PLA, and was attached to a Kossel Mini with a heated bed. No heated chamber, just a heated bed.





You can clearly see that the combination of belt tension and heat from the bed and possibly motor heat has warped this part quite a lot. I first noticed that the belt was riding on the flange, and was tilting as the belt moved back and forth. Hard to describe but it's quite noticeable if you've got that problem. My motors don't get hot per se, maybe slightly warm after a long print.


I've reprinted these parts in PETG, hopefully these ones last a bit longer!


What material would be best for printed motor mounts, assuming that you don't want to use metal? Anyone with a lot of experience of these parts?

PETG will do a bit better, but it will still not work as well as ABS or HIPS in this situation.
PLA is just the wrong choice for pieces that have to endure tension, torsion and a bit of heat. The heat from the motor alone is often sufficient to soften the part.

---

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Quote
nebbian

What material would be best for printed motor mounts

Aluminum

I was using a printed ABS mount in my printer's X axis. The printer has a heated bed and enclosed build chamber that gets to about 45C without adding any additional heat.



The heat from the motor and the belt tension were causing problems. I noticed that the motor was tilted slightly in the mount and when I took it apart I found the screw holes distorted. The motor runs warm, not hot. I suspect the problem is the combo of heat and pressure (tension) are causing the plastic to creep.



I replaced the plastic with aluminum. I started with a mount I bought on ebay for $20 (left side) and made a few cuts on a mill to make it fit my machine, keeping the motor in exactly the same location it had previously occupied with the plastic mount.



I printed a small piece to mount the X axis limit switch:



Next, I have to replace the printed belt tensioner/idler:



Edited 2 time(s). Last edit at 06/03/2016 06:41AM by the_digital_dentist.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Has anyone used something like this RS temp labels for monitoring motor temperatures? 60 or below shouldn't be a problem but heading up this scale towards 90 on a continuous basis would be cause for considering reducing the current or installing a larger motor. These should be small enough to be mounted on a 40-48mm nema 17 motor.

---

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

If fan costs one euro or dollar and filament costs some cents, could it be feasible to add 40x40mm fan to the end of the motor? Would it cool down the motor? The surface temperature of motor iron would cool down but would it extract the heat from coils and their lacquer which is the first place which brakes down with heat.

Motors shouldn't be running hot really but its inevitable sometimes that you end up turning up a motor's current slightly too far and it gradually gets hotter and hotter. Making printers out if pla is also not ideal.

I'm not sure this is about motors themselves being damaged by overheating it's the plastic parts they're fixed to that are a problem.

Edited 2 time(s). Last edit at 06/06/2016 06:02PM by DjDemonD.

---

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

I think the permanent magnets will be damaged by high temperatures. Most steppers are only rated to about 90C although you can get extended temperature range ones good for about 130C at the case. 90C max would normally be fine - pushing my nema14s quite hard only gets them to 60C with 20 ambient, but if you want to print in an enclosure at say 50C then suddenly that 90 looks a lot closer. And to be honest, I'd be uncomfortable with the motors operating at the max rated temp for hours on end. I suspect I will need to increase the reduction gearing to allow the motors to run at lower current, but I have been toying with the (probably bad) idea of adding a peltier cooler and fan. Piping in cool air from outside the enclosure is probably a more sensible approach.

I think water/liquid cooling would be more efficient for hotend and motor cooling in an enclosure. For the OP's printer, I'd sacrifice 12.7mm of Z height and add some rigid insulation under the bed.

Thanks for that guys.

DD, I'm surprised that an ABS part would warp. I would have thought that it would be fine at those temperatures. I guess the killer here is the torque on the motor from a belt that is not in line with the motor mounting screws, combined with heat. No real way around that apart from metal mounts I guess.

Srek, have you used HIPS before? What's it like in this application?

I only tested it a bit. I ended up using ABS for most printer parts and PC for parts close to the nozzle

---

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]