Bottom corners curl up during printing (warping?)

Hello,

I use the Ultimaker2 which has a heated glass plate at 60 degrees celsius (140 Fahrenheit) as standard setting. As you can see in the image the bottom corners curl up slightly despite the brim i use. Even the brim is pulled up by the object. The filament is PLA.

Attachment 6188

As the object is on the plate for many hours, i think it shrinks like loundry that is overheated. So first question: how can i tell gcode to lower the temp of the glassplate after say 5mm. The object then is heavy enough by itself not to move around. And i can put some "glue" under the object to fixate it.

Or is there another reason why this happens?

Thanks.

try slowing down the first layer print speed. And I mean REALLY slow. I run mine at 10% of print speed and usually print at between 50 - 70mms.
That way you get an awful lot more adhesion to the print bed.

If that doesn't work - wipe the bed with a gluestick.
But be warned - slow first layer and glue stick can be almost impossible to remove :-)

Thanks.

Board is ready. Beautiful result. But measuring shows that the first centimeter has shrunk over all by 10% and some more on the edges where it curls up.

What i'll do now is
- print it laying down in stead of standing up (the board is 130x105x25).
- print the first layers with brim very slow (thanks for the advice).
- Then after 5mm i lower the temp of the glass plate to 30 degrees C.

Any more suggestions?

don't lower the bed temp. The longer the plastic stays soft, the flatter the base will be.
Cooling the bed just encourages the plastic to shrink.
So keep it at 60 for the whole print.

10% ? shrinkage, with pla ?
That's just wrong, hell even abs only shrinks by 1%. What pla are you using ?

10% in the corners. I put a small square in each corner and the ones in the bottom corners are rectangles by now. See images. It should have been flat with a small fillet. The one on the left is empty on the inside, the one in the right has a 15% fill but still curls op on the corner. On a third attempt even the brim curled up.

Attachment 6191

Wait.... you're not using an adhesive?

Quote:

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Originally Posted by Marm

Wait.... you're not using an adhesive?

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The UM2 has a heated bed. For smaller things adhesive was not necessary. Now 'll put some glue on the glass. I'll be back with the results.

Yeah, Even with a heated bed, I ALWAYS use glue. Check one of the thousand threads we have here on bed adhesion for tips.

Used a household glue stick and that helped.

You can smear a layer of glue on glass to make the filament stick to it.

Best tip, Curious aardvark. Slow bottom layer + glue stick and fine results.

Thanks, Jeex exit

oh yeah that works. But it can be an absolute sod to get the models off.
here's a tip. If you've got two models close together and you're using your digital calipers to lever them off the bed. Don't hold the sharp end in your hand.
Removed a fairly deep strip of skin from a finger doing that :-)

The only solution for getting them off is patience. Wait for the glass to cool off.

You can also try to edit the STL file and add pads at the corners, for example 10mm diameter circles, 0.5 or so in height. It will help to reduce the stress at the corner and distribute the pull over a wider area.
I attached a picture to show a part I made, the printing pads are easy to cut away after printing, they also help to get more leverage to unstick the part from the print bed.
Attachment 6249


Hmmm, that image came out very small... you can see the thing here.

Quote:

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Originally Posted by CaptainObvious

You can also try to edit the STL file and add pads at the corners, for example 10mm diameter circles, 0.5 or so in height.

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Yes, or add stl files that you already have ready:

http://3dprintboard.com/showthread.p...light=davopads

I use painters tape, and even hit it with hairspray, no curling but can be a PITA to remove. The tape is usually stuck pretty good to the part once i get it removed, then i just use some solvent, similar to goo gone to remove the tape.