My adventure with PLA has ended in heartbreak. It wasn’t working very well so I switched back to ABS – which was fine for a few prints. Until I found it just wasn’t extruding and stripping the filament.
So, disassemble time. My filament looked like it was getting shoved into a jam and splitting apart like a banana – with the center making it down to the nozzle through a small aperture. I found I couldn’t remove the insulator – and upon looking closer found that a very small amount of PLA had oozed down and around the nut above the insulator/ washer. I removed the extruder assembly from the ‘bot, and the heater assembly from the extruder, heated it back up and slowly removed the PTFE insulator. I found the barrel was clogged with ABS as was the insulator.
I’ve managed to clean out most of the insulator, the nut, and the threads of the barrel using drill bits and precision screwdrivers.
I’m going back to ABS, I would rather deal with warp than the heartbreak of PLA ooze into the threads of my heater assembly.
That’s pretty much how I feel, I’m going to go back to ABS. I decided to get a heated platform to make it easier. Particularly frustrating considering I was printing in PLA for weeks perfectly until I had my first failure and I haven’t been able to get it going again. I’ll probably end up building 2 extruders. One to do ABS normally and one to experiment with PLA.
Hi Tony,
Thanks for the comment. I saw someone had posted a very cool design for a quick swap extruder head. I rather liked the system. Ultimately, I’ll probably follow your lead and go with a second extruder just for PLA. I was hoping to avoid that, but I don’t see how I’m going to print with PLA otherwise.
How did you manage to print with PLA? I just used my ABS settings which was fine for a very short time.
I think part of my clog came from leaving the heater too long while I was doing other things. I noticed that unlike ABS which I could leave stewing for a while, PLA would ooze out in a dark amber color. I have to wonder if the PLA was undergoing some kind of change.
MakerBlock
I managed dozens of successful prints in PLA: http://www.flickr.com/photos/tbuser/sets/72157623128976713/
All I did was lower the temp slightly (about 5 degrees) compared to ABS to keep it from oozing too much while the motor was off. That was literally all I changed. Worked great until it apparently clogged up and broke the retainer and idler wheel. Ever since, after several tear downs and rebuilds, I could never get it to work again. The residual ABS might have had something to do with it. I also noticed if I let it sit, heated up, and not extruding it would liquify and drip amber colored droplets. It’s possible that liquidification and burning was causing a harmful buildup in the barel and nozzle.
I had the same experience with the amber droplets when I let the heater sit with PLA in it.
I have to wonder if our clogs were caused by: letting the heater sit, heat traveling up the PLA (which seems to hold heat MUCH longer than ABS), the PLA becoming gooey inside the insulator, when we turned the motor back on it forced the gooey PLA downwards into the threads and barrel, it stayed that way so long that it had a chance to cool and develop a blockage in the PTFE.
MakerBlock
Don’t give up on PLA! Its so nice to be able to have a perfect print every time. Plus no raft! Once you find the right settings and configuration it works really well. Get a thermocouple and run it at the lowest temperature where the top of the barrel will be at 160-165C.
The only thing I don’t like about PLA (after getting it working) is that it puts out really gross fumes. You can smell it a lot and it gives me a sore throat every time I use it.
Another really great thing about PLA is that since it retains heat so well, the nozzle never gets stuck on a piece of hardened plastic. With ABS, a few prints failed because the nozzle snagged on a piece of plastic that was too far up because of the wrong operating speed and it lost a few steps and failed badly. With PLA, the nozzle just pushes it down and it continues perfectly.
It took me a month to get PLA working, but I’m glad I spent the time to do it. You should really try to get it working.
*sigh* PLA broke my heart. I managed to print a very few parts with PLA – one of them a bed spring for a full sized Mendel. The part came out stringy and brittle. I don’t think it is forgiving enough to work as an actual spring. ABS, by comparison was great – except for some minor warping and the whole raft thing.
Don’t get me wrong – I’d love to be able to print in PLA (after all, I did invest in a 5 pound coil) – no wasted plastic on rafts and no warpage.
Hmm… your comment gave me an idea for a test…
Thanks,
MakerBlock