MakerBot Industries

PLA jam!!!

My MK4 Plastruder is made of entirely stock parts, except for a printed insulator retainer, and worked great with ABS.  My first attempts with PLA about six months ago were alternately wondrous and horrific.  While trying to dial in the proper temperatures for my Plastruder for use with PLA I cranked it too high, the PLA tried to expand inside the insulator retainer, and liquid PLA was forced around the threads of the extruder barrel.  As I said, it was a horrific mess.

How horrific you ask?  Just take a look at this picture of my MK4 plastruder after I tried to extrude PLA:

BLOCKED

Yeah.  It was that bad.  Well, this weekend I gave PLA another shot with my MK5 Plastruder.  At one point I realized I was trying to print while still using the ABS profiles – and heating the PLA up to 230 degrees Celsius.  This was also happening while I left the area to put my daughter to bed.  The result was the extruder was operating way way too hot for way way too long.  These are not good things.

The result is the extruder kept the heat at 230 degrees Celsius, the PLA formed a blockage, and extruder motor kept forcing new PLA down into the extruder barrel.  However, due to the way in which the MK5 is designed, there was no place for the PLA to create a mess.

When I realized what was going on I shut down the extruder and pulled out the filament, pictured at the top of this post.  What you’ll notice is the area of the filament to the right is still clear/translucent while the filament to the left, which was down inside the extruder barrel, is a milky color.  Interestingly, the clear area of filament is still just as flexible as a normal piece of filament while the milky white section is extremely rigid.

This situation, running the extruder too hot for too long, would have been catastrophic for my MK4 plastruder and was basically shrugged off by my MK5.  All I had to do was loosen the thumbscrew for the Delrin plug, yank out the filament and blockage, cut that section out, shove newly cut piece of filament back in, and tighten the thumbscrew again.  This was the difference between a 30 second fix with my MK5 as compared to a problem that actually ruined my MK4 insulating barrier and kept me from printing until I got a replacement.

I’m still dialing in my temperature settings for PLA and will be posting some of my results later today.