PLA to ABS

Hey everyone :slight_smile:

I’m a newbie to 3D printing and of course I got my hands on a Taz 4. I’m going to be switching from ABS to PLA, vice versa. I have ABS loaded in my printer now. Should I let the printer head heat up, remove the ABS filament as it heats up, and unload the filament as gets softer in the print head? Do I then let is cool before loading the PLA?

And as far as printing with PLA, I’ve read so many mixed things for so many printers. For the Taz 4, do I need blue tape, cool bed, heated bed, or glue stick, etc? I’m a bit confused :frowning:

Here’s how I switch from ABS to PLA:
(Be careful of course, because the extruder will be hot enough to seriously burn you if you touch it.)
After I printed my last ABS print, I cut the ABS filament off a few inches above the extruder and put the ABS away.
So now I mount the PLA roll, thread it through the guide tube, and then heat up the extruder to ABS temperature.
Just as it’s coming up to temperature, I relieve the tension on the feeder and pull out the ABS stub with long-nose pliers.
Then I insert the PLA, pushing it into the extruder until I see molten plastic flowing from the nozzle.
I quickly tighten the feed tension and I begin extruding 5 - 10 mm at a time via Pronterface.
I watch for the color change, and I continue extruding a bit after the color has fully changed to the PLA filament.
I quickly turn the extruder temperature down to the PLA setting and I keep extruding every few seconds because I don’t want the high temperature to creep up into the tube above the hot end, as this could cause a jam from expanding/melting PLA. I keep extruding until the temperature is close to the PLA setting.

This will be difficult if your ABS and PLA are the same color, so you should do it with different colors first and keep track of how much you had to extrude before the ABS was flushed out. You don’t want to decrease the temperature until you’re sure all the ABS is purged from the extruder.

I’ll let others give you recommendations on the bed coating. I recently removed the PET and my last few prints were PLA on glass with hair spray. It’s sticking OK for some prints, but not quite enough if you have small features that need to stick, so next I’ll give a try with glue stick.

I did like the PET film, except that I kept hacking it up when I pried the prints off, so after 2 sheets I decided to try directly on the glass.

for PLA I use hairspray. But if your switching back and forth a lot it make not be good as it takes a bit to clean it off.

My PET is long gone and a pain to replace so I print right on my glass. When the print is cool completely you can hear it pop off the glass. It will then just be sitting ther. no need to pry. remove the print hit the bed with more spray and print again.

when switching back to abs I use a razor blade in a paint scraper and take the hairspray build up off and clean the glass real good then do my ABS.

@jeb: Cool, thank you so much for your input!:slight_smile: That sounds like what I had to do to remove the ABS that was in the printer when it was shipped. I ordered silver filament from Prototype supply, but they ended up sending me blue… which I may be able to tell the difference against the Black ABS…I hope!

@chiphead: Thank you :slight_smile:! This is going to sound so foo-foo and girly, what kind of hairspray? Heheh will the “Super Mega Ultra Hold” be too much? Or just a garden variety Aqau Net brand?

Sounds like a Glue stick and hairspray thrown down may be happening :smiley:

I use Suave Max Hold. Rock solid adhesion, while hot (80c) its near impossible to remove the print. I put the fan on and when its cool you will hear a loud crack like the bed just broke, but its not. The part will be laying there unattached or just slightly.

And it smells purdy!

I prefer glue sticks for PLA. They wipe off clean with a little water and a paper towel. No residue to deal with at all and a pristine glass bed for each print.

With PLA I recommend you print a new fan shroud to cool the fins on the nozzle. Without a cooling fan the nozzle suffers from “heat creep” during longer prints where the PLA transmit heat up itself which then expands and jams the nozzle. Here’s a link to the one I use currently: http://www.thingiverse.com/thing:374906 Its a swap in replacement for the fan shroud that comes with the Taz 4. If you start suffering extruder jams prior to printing that than just point an external room fan at the printer which will do the trick too. Shorter prints usually work fine without as long as you don’t preheat until right before you print.

I usually heat my bed to 55C for the first layer and 50C after which works well.

I just published my remix of the above referenced thing http://www.thingiverse.com/thing:428936

I added a 9g servo mount for auto bed leveling.

Oohh, neat. I have one of those servos in the helicopter parts box too!

@chiphead: hahah thanks! Yeah I get nervous when there’s loud “SNAPS” around electronics, thanks for the heads up :slight_smile: You smart types and your neat leveling thingies!

@scuttlebot: Thanks for the additional info and link on the fan. I’ll probably give the glue sticks a try first since it sounds like it’ll be easier to clean up if it doesn’t work out.

I really appreciate everyone’s feedback and advice! :slight_smile:

I am thoroughly befuddled. I made the first few prints with my TAZ 4 out of PLA and the parts came out beautifully.


I then switched to ABS and only messed around with the print settings (I did not dare tweak the printer calibrations once it had been leveled out) to figure out the ABS sweet spot on my machine. I then switched back to PLA and it metaphorically seems that “all hell has broke loose”. My PLA is not linearly stacking properly and it is warping off the table; it seems to be drunk when the PLA filament goes in. :confused:

The thing that is driving me up the wall is the ABS is working perfectly, which is the tougher of the two materials to work with, and PLA is riding the short bus to struggleville right now. :cry:

I am at a lose right now, does anyone have any brilliant ideas that I may have missed? Thank you all!

@chiphead, which material is best for the bed-leveler/fan ? further more is there a good place to read how i would change the printer settings for sclicer/pronfance to use the bedleveler etc :smiley:

i hope its not to advance for me

//bre

Hey everyone! So seemslike I got the hang of ABS…until today. All my parts were printing straight, sticking to the bed, and supports were popping right off, and then I get this…phenomenon.

The only thing I can think that happened is I loaded profiles into Slicr and it defaulted my “printer” settings back to default (it didn’t have the Taz bed dimesion settings. Didn’t notice until after my print had been running for a bit). I didn’t print with supports, and i had a skirt as high as my piece as I have to do draft protection until my enclosure is finished.

I ended up with this leaning tower piece-a. Any ideas? There’s no curves in the +y direction…so I’m a bit perplexed.It stared off janky the got straight half way through the piece. Do I need to re-level the bed?

Exturder was at 230(started @ 235) bed was @ 110 (started @ 115)
Used “Fine” lulzbot preset in Slicr



Your X axis belt may be a little loose. They should be as tight as the Y axis belt. Also check the belt pulley on the X axis stepper motor. When a print is paused, you should not be able to move the X axis left or right by pushing on the carriage.

I re-leveled my print bed, turns out the front left corner was a bit too high. Though I’m still going to inspect the belt like you suggested Orias. If it is a loose x belt, how would I tighten it? Thanks so much for you help and suggestions! :slight_smile:

+/- X won’t budge :slight_smile: So this looks like it may have been a case of user error…surprise, surprise :wink:

When tightening the belts, use this method to judge the tension:

http://www.leggebeef.com/finger-test-meat-doneness.png

Loosen one of the belt clamps on the axis, and pull the belt tighter, then tighten the belt clamp to re-secure the belt.

Hah! This is pretty cool! Thanks Orias :slight_smile:!

And we need it to be medium or well done? :laughing:

Medium-well to well works… well… Well!