Prints pulling up at corners

[jimc]

Dont use a raft. Use a brim. In s3d set the skirt to zero offset, maybe 12 perimeters and 2-4 layers depending on what your layer height is.

[PcS]

I would suggest leaving the bed cooling fan off altogether . The large bed sized prints typically don't need it. Put a large cardboard box all the way around printer but leave top open. My house is always cold and just a simple box to keep drafts away was a huge improvement. Petg will perform better for this ....but is harder to initially dial in.

[naturalstate720]

The box sounds like a decent idea. Because I feel like I've done everything. And since the raft isn't warping, but the prints on top of raft are that at least to me, indicates that bed is level and adhesion is working fine.

I just hope these two models don't look like sh*t when I glue them together bc of warping. I've heard sanding is very good with PLA. What about putting it down on a belt sander and really trying to take some layers off to make it flat again so that 2 pieces glue together nicely?

[jimc]

Pla sands and machines terrible. It just gets warm from the sanding and then it softens up. Abs sands and machines great. A raft will aways have some give to it. A raft keeps your print stuck to the bed but doesnt lock it down tight to keep it from warping. With a brim your part is printes direct to the bed and a flange is put around the print to hold the corners down. Your part will stay much flatter with a brim. The box that pat mentioned is great and alot if people do it for abs. watch it doesnt get too warm though. It can cause jamming if the heat creeps up the hot end a little because it cant cool itself.

[naturalstate720]

Ok, so adding box and using brim and turning fan off completely. Are we sure about turning fan off completely? God I hope this works, I had no ideas how complicated it was going to be just to print a building.
I might get fired if after three weeks I've failed printing the project that is due Wed.

So my layer height is .2mm
And I'll set my skirt to zero offset, 12 perimeters and how many layers do you think based on my layer height?

But don't I still need a skirt do purge plastic out of extruder to prime it first? This always seemed helpful. I can't do that if I do the brim right? Because they are the same setting.

Thanks for advice!

[Jules]

The brim is a skirt, just one that is attached to the print. You don't need both.

Good luck! (And let the print cool completely before removing it. It can warp if you pull it off too soon.)

[naturalstate720]

I think I've read at least 15 minutes to pull off? Or a lot longer?

Thank you

[jimc]

If its a large area, which it appears to be then no fan is needed BUT if you maybe have details toward the top of the print where the print time on each layer is really quick then you will need the fan on for that. Pla is rubbery until it reaches room temp. You dont want to put your next layer on top of a rubbery base. That will cause your details to come out crappy. It all depends on your print and every print will be different.

[Jules]

Pla is rubbery until it reaches room temp.

This! I've ruined many a print by prying it off too soon.

[naturalstate720]

So I did 12 outlines, 0 offset, and 4 layers. But it sure doesn't look like 4 layers tall. It looks like a very thin smear. I don't see how this is going to prevent warping. It seems just like a regular print with a little bit extra on the bottom. Did I do it wrong?