PLA warping?

I have a weird issue with PLA warping.

I only recently started working with PLA because I don't have a heated bed yet and ABS was warping on me. I was hesitant to try PLA because I have an all-metal hotend and had heard stories of PLA jamming, but thankfully it has worked beautifully with zero jams so far.

I'm printing onto a sanded aluminum plate using purple Elmer's glue stick (PLA would not adhere to a polished surface, so I scuffed it up). Everything works fine, but I noticed I'm getting significant warping at the corners of my prints. It's bad enough to screw up some prints of a raspberry pi case that I have tried.

I didn't think PLA required a heated bed. Any ideas why this would happen?

Printing too fast, too hot, or insufficient cooling air will cause PLA to curl on overhangs and corners.

PLA on non heated build plate = blue 3m painters tape 2090
it's like magic.

A related question for the more experienced, is moisture content a factor in warping?

Walter, is that tape you're referring to also known as "masking tape"?

I tried tape breifly, but hated it because it tended to rip off and stick to my prints. It was difficult to remove from them, so I decided to use something else.


This is likely my problem ---> "Printing too fast, too hot, or insufficient cooling air will cause PLA to curl on overhangs and corners."

I don't think it is speed, but I do not actively cool my prints and I print higher than is probably recommended. I find if I drop my temp, my extruder has trouble pushing the filament and slips.


Edit: I dropped the temp and the warping has decreased. I will experiment further.

Edited 1 time(s). Last edit at 11/23/2014 09:54PM by mk3a.

Quote
mist42nz
Walter, is that tape you're referring to also known as "masking tape"?

It is in the UK

I print from 190c to 210c..

I dont get warping on either temp...
Lately I have been printing on blue painters tape, I use a small amount of olive oil, Wipe it all over the tape, then use alcohol and wipe of the access...
let it dry for a few hours and give it a print...

It makes my tape last ages and the print just pop off...

this might help you with getting your prints off nicely...not going to help the warping tho...
make sure bed is level and give a fan ago... and play with speed.. to slow and you will def get warping.. well thats what i experienced... above 40mms is good

blue painters tape/masking tape yup same thing
but it's marketed as painters tape

i have not tried regular masking tape, only the blue 3m 2090 stuff

@ mk3a try this it worked for me

[forums.reprap.org]

Interesting I see a mention of warping being caused by printing too fast and also a mention of it being caused by printing too slow...I'm confused.

Well i know with first hand experience, printing to slow will warp because the part is getting to hot.

What are your settings?
Have you double checked that your temp is what it sez it is?
post some pictures if you can.

nechaus,

This ties into another post I have about printing speed: [forums.reprap.org]

I don't really have a way to double check the temperature. I bought an infrared thermometer, but I've found it to be unreliable. But this is what I do know:

I print ABS at 250C and 20mm/s and it prints wonderfully, except for some warping due to not having a heated bed.
I can print PLA just fine at anywhere from 220C to 250C and 20mm/s, except for some warping (Yes I know this is way hotter than people recommend, but bear with me).
If I drop the temp below 220C I start getting weird banding in my prints like this: [imgur.com]
If I drop it further than 210C or try to increase the speed past 20mm/s I can hear my extruder grinding on the filament and the banding becomes outright gaps.

I would like to drop the temp and / or increase the speed, but these issues are stopping me.

It sounds like your thermistor reading isn't accurate. You're probably printing at an actual temp of 185C but your thermistor is reading that as 220C. You might have the wrong thermistor table set in your firmware.

sheck626,

Pretty sure that isn't the case because I can print ABS at that same temp. I'm also certain I have the correct thermistor table selected.


Edit:

I was able to print at 195C after tightening the idler on my airtripper bowden extruder. Things are looking up.

Edited 1 time(s). Last edit at 11/27/2014 08:16PM by mk3a.

I'm printing on Kapton tape, works fine. If it doesn't stick I apply acetone while wearing gloves and after that it sticks great. I am printing on the same piece of Kapton now since early April and haven't had any trouble.

The only thing I can say is that the manufacturer of the Kapton makes a difference and the quality of your PLA in combination with this Kapton can make a big difference. I know what vendors sell the PLA I can use, but only after having a lot of trial and error.

---

http://www.marinusdebeer.nl/

I had warping till I printed a print cooling fan. It runs 100% after the first layer. Not an ounce of warping on a 16hr print. I print at 60mm/sec and 225° and 1.0 extruder ratio.

HTH,
Seth

honestly you need to check the temp...

Because if there is the chance the temp is correct then your getting jams in the hot end..

but sounds like its off..