MakerGear Forum

I am currently printing with a red PLA filament that has exhibited great behavior on one project, and very bad behavior on another. Wondering if anyone else has seen this kind of Jeckll and Hyde behavior, and what was the solution?

The successful project, I printed a number of objects (geared heart from thingiverse) that practically covered the entire build plate. I am printing to the white side of a zebra plate. No warping at all, including the parts whose perimeters were almost at the very limits of the BP.

I then went to print a single object that used approximately 60% of the build plate's surface area, and occupied 60% of both the width and length of the build plate. Had great initial adhesion, but after several hours, had the treaded corner warpage. Because I'm printing to the zebra-plate, I'm using a cooler extruder temp, 205C, and the bed is practically off at 40C. I've had great results with the zebra plate on another project with another filament. But the initial results with the geared heart with essentially no warping, albeit on smaller plate contact surface area objects, had me expecting good results with the much larger object.

Is there a conventional wisdom here? If its got a very large surface area/linear dimensions, I'm going to need a very well behaved PLA (like eSun PLA+) no matter what? Should I have used more extreme settings for the larger object, e.g. lower extruder temp, and higher bed temp, despite using the PEI print surface?

Large area PLA prints warp worse than smaller ones at corners, and you have to let the object cool completely while still attached to the plate if you don't want the PLA to keep warping after you take it off the plate.

And by completely, i mean several hours to overnight. Can't tell you how many large flat prints ruined themselves after I pried them off the bed too soon.

Some things you can do:

1. Increase the infill. Anything over 50% tends to stay down better.
2. Point an additional desk fan at it to cool it off more quickly, or remove the fan guard on the bed fan for more air output.
3. Leave the print attached to the plate. There are forces at work that want to twist and shrink the plastic. Leaving it stuck to the plate until those forces normalize will keep it from twisting after you take it off. (It sets the shape.)
4. Put some hairspray on the Zebra. Yes you can do that - it's not normally needed, but sometimes the design requires it. Be sure you have the Zebra clamped down, and leave it clamped down while it cools. (Zebras can warp too, and if it's stuck tightly to the print, the actual zebra will warp.)

That should help some.

To Jules' point on the post-print warping -- on large pieces you can (and maybe should) anneal them. Bring the entire part to a uniform 65C and keep it there for an hour, then cool it naturally. A crockpot works well for this, if you can fit the built plate in there.

insta wrote:To Jules' point on the post-print warping -- on large pieces you can (and maybe should) anneal them. Bring the entire part to a uniform 65C and keep it there for an hour, then cool it naturally. A crockpot works well for this, if you can fit the built plate in there.

Really? Did not know that, and I've got a crock pot. (Hope future stews don't taste funny! Chuckle!)

Not sure where to post this question, so thought I'd start with my own thread. Its similar to the original question. If I print something with a base that's 20% of the build plate surface, its a successful print, with very little to no warpage. But if I print a single large object that is more than half the linear dimension in X or Y of the build plate, I get warpage. I am at this minute, printing two objects side by side with footprints each in the 20% of the bed surface area range, and was getting (slight) warpage on one object, and not the other. The object that is warping, is on the "extruder fan" side of the build plate. I've noticed this issue for awhile now, but never connected that the warpage is happening on the side where the extruder fan is blowing all the time.

Has anyone else had a similar experience? Should I turn the fan down/off? I'm printing on a zebra plate with the heater practically off (40c). So the fan could supply just enough extra cooling to cause uneven cooling to one side of the print versus the other.

You can increase the heat on the build plate to compensate for the warping. Try 50-55 or even up to 60 if those don't hold. You might also find that printing with the white side of the zebra facing up causes more warping problems than printing with the black side up. (Black retains heat better, white reflects it.)

The other possibility that you might have because you are using a Zebra plate is that it might have some warping in the plate itself. Make sure it's flat, and if you need to, bend it back into shape, and make sure you have it clamped down.