Last night I stopped in and took a look at why the Polar 3D printer wasn’t working. Turns out someone was using filament other than PLA and didn’t purge it afterwards. The PLA filament melts at 200C, but materials like ABS and Nylon are much higher temp. When those materials are not purged (by running PLA through the extruder until all traces of the previous material is gone) the extruder does not heat up enough when using the Polar 3D Desktop software (which is tuned specifically to PLA) to melt the previous material out. That caused the jams we were seeing.
The solution is very simple… if you are using Repetier-Host with the Polar 3D and not using my default profile, then you MUST clean out the nozzle prior to shutting down the machine by running a length of PLA filament through, starting at the temperature you were running the previous material at. Be very very careful to not let the PLA sit idle in the hot extruder, or it will burn and caramelize in the nozzle.
Also, the profile I set up in Repetier-Host was modified to a much higher temperature than PLA can handle, which also causes it to burn in the nozzle. It is important that you create a new profile and not modify the Polar3D profile I created so we can avoid these jams.
The preferred method, to me, is to simply use PLA only… that eliminates all the issues.