Help - Extruder stepper melts PLA

[hcdbey]

Relatively new to my Rostock MAX V2. Have gone through 1 kilogram of ABS and started on a reel of PLA. I had printed about 32 meters of reel of PLA at 210 degrees hot end temperature and 65 degrees bed. Today, I was about 100 minutes into a print when I started to hear strange noises from the extruder stepper motor. The stepper knowb was not turning and no filament was coming out of the hot end.

I shut down the machine and examined the EZStruder extruder assembly. There was melted PLA at the hobb gear.

The EZStruder has been disassembled and the melted PLA has been removed. I was concerned that the stepper motor was burned out but I have tested it and it runs although I have not reassembled the EZStruder or fed any filament with the motor yet.

Does anyone have suggestions as to what is causing the extruder stepper motor to get so hot that it melts the PLA when it comes into contact with the hobb gear?

Thanks

[geneb]

The current for the stepper motor is too high. When did you download the firmware for your machine?

g.

[hcdbey]

I probably downloaded the firmware on about 7 September 2015.

[geneb]

Grab the latest from github - it should have the revised current settings in it.

g.

[hmanvel]

I had the same problem and found some advice on this forum to add a fan to the stepper motor. See attached photo. It's an old CPU fan from a junked computer. Works great, no more melting.