Edges of part are lifting up

[mharter]

Hello everyone!

Whenever I print a larger part with a large, flat surface...the edges lift up and start to warp. I print PLS @215, bed at 60. My printer is located in my basement right off of the garage. I am thinking that I need to build an enclosure to keep the temperature constant. The print I made last night was interesting and I think supports my need for an enclosure, just want some confirmation. My print was about 9.25" x 6.5"...a large surface area print. The back of the platform (closest to the garage wall) began lifting up. The front of the platform, (closest towards the center of the room) stayed adhered and flat on the glass. (used hairspray with the glass to help with adhesion). So, it seems that temperature variance is causing the back end of the platform to warp up, while the front part is perfectly adhered.

If anyone could verify that I am thinking correctly, that would be greatly appreciated. If so, I will get on building the enclosure I have seen on here (the ikea parts).

Thanks all!

Mike

[insta]

Point a small desk fan at the rear of the printer (position it on a milk crate or something equally ghetto) and see if that fixes it. If so, you need more cooling, not less from the enclosure.

[mharter]

I will give that a try, but I don't think it will work. The back end of the printer is currently the cooler end, adding a fan will cause it to cool even quicker. The front of the printer is away from the wall and is where the part had perfect adhesion to the glass.

Unless my logic is wrong. I envision the cooling similar to injection molding...the quicker the plastic cools, the more warp and shrinkage the part will see. That is my thinking for an enclosure that keeps in the heat. Keep the unit more evenly temperatured.

Thanks for taking the time to address my question!

[insta]

Yeah, but PLA doesn't behave like a normal plastic, it barely contracts as it cools.

Also, make sure your glass bed is VERY clean (hot water, dish soap, multiple scrubbings until it's legitimately perfectly clean front & back), then apply a heavy layer of hairspray, and only then place it on the printer and begin preheating.

[mharter]

Yeah, but PLA doesn't behave like a normal plastic, it barely contracts as it cools.

Also, make sure your glass bed is VERY clean (hot water, dish soap, multiple scrubbings until it's legitimately perfectly clean front & back), then apply a heavy layer of hairspray, and only then place it on the printer and begin preheating.

Gotcha..thanks for that little tidbit of information, was unaware that PLA behaved like that.. I think I need to lay down the hairspray a little bit thicker than I have been.

[jsc]

Cooling is useful for PLA mostly because it has a tendency to curl up on overhanging surfaces unless the plastic is cooled immediately and dramatically. But that doesn't seem to be your current issue.

My take is that your bed is not sufficiently level, and the rear is slightly farther from the bed than the front, so you are getting less adhesion. You can eyeball this by bringing the glass right up to the nozzle but not touching it, and with your eye almost parallel to the glass so that you can see the nozzle and its reflection at the same time, move the bed back and forth and the extruder left and right, without moving the bed up and down. You should be able to see how the gap shrinks and grows as it's moved around. Even with a "perfectly" level bed, there will be some changes as the glass is slightly domed in the center. Adjust leveling until the edges are all approximately the same height.

[mharter]

Cooling is useful for PLA mostly because it has a tendency to curl up on overhanging surfaces unless the plastic is cooled immediately and dramatically. But that doesn't seem to be your current issue.

My take is that your bed is not sufficiently level, and the rear is slightly farther from the bed than the front, so you are getting less adhesion. You can eyeball this by bringing the glass right up to the nozzle but not touching it, and with your eye almost parallel to the glass so that you can see the nozzle and its reflection at the same time, move the bed back and forth and the extruder left and right, without moving the bed up and down. You should be able to see how the gap shrinks and grows as it's moved around. Even with a "perfectly" level bed, there will be some changes as the glass is slightly domed in the center. Adjust leveling until the edges are all approximately the same height.

Another good point, that I would not have thought of this soon in my debugging process...thanks! Now if the work day would just end so I can go home and experiment...ha!

[jdacal]

I usually run my bed at about 70 on my printer. Have recently been trying it at 60 and was noticing curling on the PLA corners. Raised it back up to 70 and the problem stopped. Not sure if that will help you but might try it. In addition to the hair spray or glue stick.

[mharter]

Well, it turned out to be a variety of issues. The bed was slightly out of level front to back, so I leveled that up. I sprayed a much healthier helping of hairspray on the glass, which also helped. There was a temperature variance between the front of the printer platform and the back, so I constructed a sealed box to help trap in the heat and even distribute it (not sure if this is much of a contributing factor to the successful print, may be the placebo effect...LOL). I also settled on a 70C platform temperature. 65 helped a little bit, but 70 seemed to be the sweet spot in the combination. After all of these minor adjustments (through all the insightful answers to my OP) I believe I have worked out the kinks to getting the print to stick and not curl up.

Thanks all for your input...problem(s) solved!

Here is an image of the enclosure I made. I am an Industrial Designer by trade working in the packaging industry, so I have an unlimited supply of almost every grade of corrugated paper, solid fiber and folding carton materials...which created this:

The front window 'pops' out to allow the changing of filaments. I have a V4 dual upgrade kit coming, so I made it wide enough for another spool on the opposite side if the original spool holder.

[insta]

Please sell me 4 of those cardboard enclosures right now