Switching from ABS to PLA

[jesse]

I tried switching to PLA filament from ABS.

How can I clear the ABS out of the hot end without taking it apart?

[mhackney]

I remove the Bowden from the hot end. Clip the filament about 2" above where it enters. Then, heat up the hot end to 220°C. Then, start to push the filament through. When 5cm or so extends at the nozzle, give it a few seconds to cool. Then, grab it and the filament above the hot end and pull each in opposite directions quickly. I find this clears the orifice if you do it quick enough. You want the temp on the cool side, too hot and you have too large a melt zone.

[geneb]

I just feed it like normal until I see the new color and then drop the temp down and feed a few hundred mm through it as it cools.

g.

[cassetti]

I just feed it like normal until I see the new color and then drop the temp down and feed a few hundred mm through it as it cools.

g.

Agreed - on my Makerbot Replicator I just keep feeding for a bit to clear out as much ABS as possible. I've never had an issue. Same story for my Ecksbot - preheat and extrude.

[mhackney]

Gentlemen, how does what you suggest work with a Bowden tube? You can't "push" one filament with another through a Bowden reliably.

[Polygonhell]

Gentlemen, how does what you suggest work with a Bowden tube? You can't "push" one filament with another through a Bowden reliably.

I do that all the time FWIW.

But the way I usually do this is heat up the hotend a bit below my usual ABS temperature (say 210-220), retract the existing plastic all the way out.
Feed in the PLA, run 200-300mm of plastic through then drop the temperature.

I'd be wary of continually connecting and disconnecting the quick disconnects on the bowden, I've had one fail.

[cambo3d]

hmm maybe i should get another add a struder kit set up just for pla, so could just swap hotends..?

[jesse]

Printing in PLA has been frustrating.

It melts too soon and stays hot too long.

[Polygonhell]

Printing in PLA has been frustrating.

It melts too soon and stays hot too long.

Yes if you have a heated bed in general ABS is a lot less hassle IMO, the advantage of PLA is you can print lower layer heights because of the reduced viscosity and it warps considerably less.
You really need active cooling to print PLA effectively, get the print temperature as low as you can then blow a lot of air at it.