[Solved] Extruder melting PLA... with reduced power

[Arondite]

Hey All,

So I've had my Rostock Max V2 for about 2-3 weeks now. I've worked through a bunch of hurdles already, but this time I'm stumped. Here is a (slightly?) organized mess of info about what's happening. Any help would be greatly appreciated, I am worried that the extruder motor is just bad though...

First some background:
Brand new Rostock Max V2 with Kysan motors, using the corsair cx750m PSU, calibrating using calipers and first layer height. Everything was printing fine in ABS, I got both first prints done successfully (hotend fan shroud and layer fan shroud).

My problem:
I switched to using PLA, it's the good stuff from printed solid. I printed out a few test pieces all within an hour to an hour and a half in print time. after getting the proper sizing I began a 7 hour print of a handful of those test parts. I woke up to 25% of the parts and a success message. upon further inspection the EZstruder was completely clogged. it was like a tangled yoyo with filament wrapped around the bolt and gear, and loops sticking out of the plastic guard.

Not the slicer or program:
My first thought was: "Man I hate how buggy mattercontrol is... I bet it just bugged out again and this time somehow the hotend got turned off." well the same print failed the same way at the same (general) spot through repetier using slic3r. So I hit the forums and found that reducing the current values have fixed the issue for a lot of people.

Not the current:
However, I already reduced the current values to 155 for xyz and 165 for the extruder as that was a step in the build guide. I wanted to verify this just in case, and in looking I noticed a comment in the code explaining that for kysan motors you need to use 140 for xyz and 160 or the extruder. At this point I'm feeling embarrassed, I'm a software engineer and I didn't read the comments in the code... so I made the change.

I hooked up the temperature sensor on my multimeter to the front (where the axel comes out and the EZstruder connects) of the motor with some kapton tape. Within 20 minutes it was at 40C, after an hour it was at 53C. This test print was only 1.5 hours and finished successfully. I thought that the temps were a bit high, but that it should be fine so long as it doesn't go much higher. Again I started the 7 hour print and went to bed. I woke up to the same tangled yoyo mess of an extruder...

Extra info that may be important:
The extruder motor has always acted a bit funny. It has way more vibration than the xyz motors, it makes a high pitched annoying electrical chirping sound (very similar to an axle that needs to be greased. but turning by hand does NOT make the same sound), and during retracts the motor 'jumps' and makes a knocking thump against the mount. Not sure if any of this will be important.


TL;DR
Kysan motors, set to 160 current value, super hot melty PLA yoyo mess of an extruder.


Edit: Solution:
To fix this I lowered the current value even more until the heat was manageable but the torque was still enough to feed the filament. I ended up using 130. Also, adjusting retracts ended up helping as well.

[Arondite]

Spoke with JJ, he recommended dropping the current even lower. When I get home from work I'll drop it down to 130 and report back how it affects the extruder.

[Arondite]

I just successfully printed two 2 hour prints keeping the temperature sensor on the extruder motor. The motor held around 38-43C. I believe this may be a success! I'll start a 7 hour print tonight before bed to see if it finishes. If so I'll marked the thread as solved.

[jwalrath]

I thought I had a similar problem. I found my extruder motor very hot and so on. Even put a cooling fan on it. Did NOT help - some prints finished but long prints still failed. With the help of mhackney, come to find that I was retracting filament too far on retraction settings. If you do a search, there he has posted a series talking about the steps to getting good prints with PLA and finding the right mix for temp, retraction, speed, etc. Once I started doing this I have not had a jam with the PLA for almost 2 weeks now. Even had several over night prints (8 plus hours).

-jeff

[Arondite]

Thanks Jeff, I'll have to look that up. As far as the motor overheating it appears that dropping the current to 130 did the trick. I mounted a temp sensor under the guard of the EZstruder so I could get an accurate read in the same place the filament passes and it's now holding under 50C. I also reduced my retracts (they were extremely heavy on this print) from 6.X down to 4. That may have helped tremendously.

I'm gonna mark this as solved. Hopefully others with similar issues will benefit from this ::shrug:: I suppose reducing the current until either the torque was too low to function, or it fixed the overheating issue should have been one of the first things I tried.

Thanks