Can load ABS, can't load PLA...

[DrUsual]

I originally had PLA in the left extruder of my Dreamer and ABS in the right. A few days ago I unloaded the left, put in a different color ABS and ran a few prints. Now when I unload the left and try to put the PLA back in, it feels like it's grabbing the PLA, but then it just goes thunk-thunk-thunk and the PLA doesn't advance into the extruder. If I unload it again and load the ABS back in it works just fine.

Any thoughts?

[Mjolinor]

Are you setting the temperature to a lower number for the PLA because you need to leave it at the ABS temperature until you get it going and the bits of ABS have gone through?

Is it a roll of PLA that you have used before or a new one that maybe slightly too thick, measure it?

[DrUsual]

Are you setting the temperature to a lower number for the PLA because you need to leave it at the ABS temperature until you get it going and the bits of ABS have gone through?

Is it a roll of PLA that you have used before or a new one that maybe slightly too thick, measure it?

I'll double check this, but I think the Dreamer heats the extruder to 230 for loading and unloading no matter what kind of material you're loading -- when you tell it to load (or unload) it automatically heats the extruder and starts turning the motor once the threshold is reached. Maybe I can tweak this, though, and haven't figured out how.

I have used the PLA before; it's one of the two rolls that came with the Dreamer. I printed quite a few prints with it before switching that extruder to ABS, which is what made me think the problem must be something in the extruder...but now that you mention that, perhaps I should try clipping a couple centimeters off the end of the PLA, in case it got deformed at the tip and isn't fitting through properly.

Thanks!

[curious aardvark]

one of geoff's tips that worked for me. Is to always feed filament through on a load cycle before running the unload cycle.

What happens is the filament goes into the feed tubed within the printer and expands to fill that tube. This is wider than the feed hole.
So you need to push this lump through the nozzle and then immediately reverse and pull out the still soft filament.

[DrUsual]

one of geoff's tips that worked for me. Is to always feed filament through on a load cycle before running the unload cycle.

What happens is the filament goes into the feed tubed within the printer and expands to fill that tube. This is wider than the feed hole.
So you need to push this lump through the nozzle and then immediately reverse and pull out the still soft filament.

That makes a lot of sense, I'll try that right now. Thanks!

[DrUsual]

Thanks guys! Got it to work now. First I took Aardvark's tip and advanced the ABS further with the load command before unloading -- when I put the PLA in, it seemed to make it further before it started "skipping." I backed it out and looked more closely at the end, per Mjolinor's question about the diameter. It looked like the tip had flattened out a bit, so I snipped off a few centimeters, ran it back through, and voila...we're in PLA land again.

Which is good, because I'm about to print a latticework for my praying mantises to lay egg cases around. The egg cases surround the supporting "twig," so I thought it would be better to do them in PLA than ABS. Probably either one is okay for this, but still...

[mikenmel08]

I have a dreamer also and stopped using the unload feature a while ago...Cause nothing but problems....Now i just cut the filament flush with the top of the machine and do a load filament.......I follow the new filament down behind the old....No more problems loading anything....

[Bobbler]

I have a dreamer also and stopped using the unload feature a while ago...Cause nothing but problems....Now i just cut the filament flush with the top of the machine and do a load filament.......I follow the new filament down behind the old....No more problems loading anything....

This most certainly fixed issues for me. I don't bother with unloading anymore at all, unless something gets stuck or starts clicking. Cut filament at top of the machine and just select load instead.

[FrankV]

I have just modified my printer to a Bowden cable setup. In the process I have seen that just the extruder (now completely separate from the hotend) makes it hard to load filament. The secret is to make sure the filament end is as straight as possible and also to press the loading spring lever as little as possible. With no power on the machine it is quite easy to push the filament through the extruder without pressing the lever at all. The actual problem is the exit hole on the extruder, if the filament is slightly curved or the lever pressed too hard, the alignment with the hole is off and hence the filament will not go any further.