Welcome to the SeeMeCNC Community

I couldnt explain fully in the title:

Since I built my kit during thanksgiving, I've mainly printed ABS, and they've been great prints. I just started with PLA, and for my first semi-successful print, about 1 hour in, the extruder stepper motor got so hot that it melted/softened the PLA and it jammed.

I do have the Kaysan motors, and I did make the following change in the firmware as per the manual:

Change: #define MOTOR_CURRENT {175,175,175,200,0}
to this: #define MOTOR_CURRENT {155,155,155,165,0}

I'll be honest, I'm not sure what these values adjust speficially. I'm assuming that the first 3 numbers are for the main 3 motors and the 4th is for the extruder. But I don't know enough about what they do specifically to just start changing the value all willy nilly.

How can I keep this Kaysan motor cool so I can print PLA?? Much appreciated!

Mine does the same thing, I've had to resort to using a fan on the stepper motor itself to keep it cool.

Poor show, these motors get stupidly hot imo and they shouldn't.

You could try reducing it further to 155 and see if that helps, but it will get to a point where it may start skipping steps on the extruder.

Since I couldn't find data on the specific model of Kaysan motors I have, does anyone know what the current & resistance rating is on these vs the original motors?

I haven't checked the Rambo so don't know what driver chip they use, but I assume it's the standard constant current chip like we use. There's two ways to set the current with that chip, two digital lines (4 levels) and an analog input. So I presume the Motor_Current numbers are D to A settings, probably 0-255.

Stepping motors should normally have the current dropped (using the digital lines) when they're not actually turning, might be harder to do on the extruder since it's almost always moving.

I am having this problem as well. It was definitely worse before the firmware adjustment, but I just had it fail (mash up my PLA in the motor gears) 5 hours into a 12 hour print... I just setup a temporary blower fan on the motor, hopefully it helps. Otherwise I guess I'll be looking for a different motor.

One thing I did notice was this: The code comment for the firmware says to use 160 (and also 140 for the xyz), but the newest manual claims the 165. I have not tried 160 yet, but I might after this print and see what happens. If anyone else has some insight here it would be helpful!

EDIT:
I overlooked this post with something I am going to try:
http://forum.seemecnc.com/viewtopic.php?f=77&t=7274
In there is a link to this printer mod. Thanks BenTheRighteous!
http://forum.seemecnc.com/viewtopic.php?f=35&t=7216

I used 110 for the Extruder motor - although I am still experimenting and have raised the current to 130 for today to see if the motor gets hot. At 110, it barely warmed up.

Has anybody replaced their motor as a test? If they're melting filament, they're at least 3 times hotter than a healthy motor is supposed to be.

I don't suspect a firmware issue at all, something is broken.

TheWalrus wrote: EDIT:
I overlooked this post with something I am going to try:
http://forum.seemecnc.com/viewtopic.php?f=77&t=7274
In there is a link to this printer mod. Thanks BenTheRighteous!
http://forum.seemecnc.com/viewtopic.php?f=35&t=7216

Awww snap. If my thread is going to be getting some attention, I'd better upload that new spool arm I promised!
Anyway, glad someone is finding it useful!

Jimustanguitar wrote:Has anybody replaced their motor as a test? If they're melting filament, they're at least 3 times hotter than a healthy motor is supposed to be.

I don't suspect a firmware issue at all, something is broken.

My Kysan motor (that I got with the 2nd extruder kit) was running quite hot (at least 55C) at recommended current settings. Sounds like some are better than others. In any case I've gone to the 60mm Robotdigg motors and I'm not looking back!