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TMC2208 Vref - Geared vs Ungeared Feeders

Posted: Mon Jul 01, 2019 10:55 pm
by Jmccoy45
Hi, I am using a pair of Geeetech MK8 Extruder Aluminum feeders (https://www.geeetech.com/mk8-extruder-a ... p-995.html) on my a10m but the stepper motor is getting very hot - almost too hot to touch. I have TMC2208 stepper drivers with their vref set to a widely recommended 0.8V. Is that too high though? I'm still using the original stepper motors, but just wondering if using ungeared vs geared feeders has an influence on what the vref is set to?
** I've been having to pause my prints halfway through to let it cool down. The feeder is so hot my filament gets soft in the mechanism and the drive gear melts into it and I start losing steps.

Re: TMC2208 Vref - Geared vs Ungeared Feeders

Posted: Tue Jul 02, 2019 9:19 am
by William
Hi, you can reduce the voltage of the driver board and increase the heat dissipation. Avoid the occurrence of motor overheating.

Re: TMC2208 Vref - Geared vs Ungeared Feeders

Posted: Tue Jul 02, 2019 5:10 pm
by TheG
Hi!

I currently also have issues with tuning the extruder motor voltage with 2208s. Everything above 0.6V appears to overheat the motor after a while. At about 0.45V, it runs cool but appears to miss steps. Now I'm testing 0.55V. I suggest you tune your 2208 for the Extruder to 0.55V as well and then try to go up/down in 0.05V steps.

I've also attached a passive heatspreader to the motor, that helps a bit. Thinking about adding a copper heatspreader with another 40mm fan, tho.

Re: TMC2208 Vref - Geared vs Ungeared Feeders

Posted: Fri Jul 12, 2019 11:20 am
by Jmccoy45
A passive cooling solution sounds ideal, bt for the time being i went with an active one. Its not pretty by any means, but without changiung the vref, i set up a normal tabletop fan and pointed it towards the extruder motor and that has seemed to fix the problem for now.

vert- it seemed like something wasn't right with those little disks in the hot end. Back when i first pulled mine apart to clean it and didn't know what they were i noticed them. Seemed even more strange when after extensive research i couldn't find any info about them or why they were there. I abandonded the factory a10m hot end months ago, switching it out for an e3d v6 configuration. My next pursuit is 2-color printing ability, which i'll get by incorporating this into my build: https://www.thingiverse.com/thing:3039887 *hopefully*

Re: TMC2208 Vref - Geared vs Ungeared Feeders

Posted: Tue Jul 30, 2019 3:34 pm
by Jmccoy45
Update: i have since upgraded to using a set of bondtech (clones) and am no longer seeing the heat problems. I'm guessing that was all happening because the Geeetech MK8 extruders i was using were aluminum and that was readily transferring heat where the plastic casing on the originals and bondtech do not.

Re: TMC2208 Vref - Geared vs Ungeared Feeders

Posted: Tue Jul 30, 2019 3:34 pm
by Jmccoy45
Update: i have since upgraded to using a set of bondtech (clones) and am no longer seeing the heat problems. I'm guessing that was all happening because the Geeetech MK8 extruders i was using were aluminum and that was readily transferring heat where the plastic casing on the originals and bondtech do not.