PLA Mid-Print Edges and Corners Lift During Print

Hi,
I'm running a MakerFarm 10' Prusa i3v with a capacity proximity sensor as an auto bed-leveling probe. I've primarily printed with ABS the two years I've had the printer, but decided to try my hand at PLA since the smell is so much less significant than printing in ABS where I can actually bear to be in the room with the printer. I printed a regular test cube at 210C with the bed at 70C on top of blue painter's tape and that printed just fine. Then I thought I'd try my hand at something more complex like Emmett's Gear Bearing. I noticed this interesting problem that happened where the slanted gear teeth of the gear bearings somehow lifted higher than the current layer height, which resulted in the hotend smashing into them while printing:





I then also tried to print a PLA copy of my probe mount to see if it was a print-specific problem, but at the right-angle corners it did the same thing:





I know some people might jump to the conclusion of "your print isn't sticking well to the platform and thus is lifting off", but not only was it hard to remove the parts from the tape after printing, on the gear bearings, the center stayed perfectly level while the outer edged gear teeth all lifted. Is it possible or likely that the center of a tiny component would stay adhered but the edges would all nearly-uniformally lift up? I found some similar issues online where it was suggested to print a little hotter or cooler, so I tried printing between 195C to 210C and got the same problem. I also don't have a fan yet for printing, I've seen printers print PLA just fine without a fan, but is it possible the lack of a fan is the issue here? Any input is greatly appreciated. Thanks!

A fan did greatly help prevent the layer curling for me. Also turning off the bed after the first layer and, if printing at low speeds, printing at 180 or even 175.

For PLA you definitely need a fan to prevent lifting, but also need to balance the infill amount, too much infill will pull the corners. Don't know how much you used but try it again with 10 to 15% less infill.

looks like you could have a little over extrusion going on too. maybe reduce the extrusion multiplyer

Thanks all very much for the tips.

1. I'll try going the route of adding a fan, though it'll take some time because I have to redesign my probe mount to fit on the other side of the carriage since the side it's on is the optimal side for a fan. I will also try turning the bed off after the first layer, see if that helps any.
2. I will try going a little cooler since I'm printing at about 50-75 mm/s, though this filament's recommended temperature range is 190 - 220C.
3. I have primarily been printing at 20% infill for things like the gear bearing, but load-bearing or structural things like the probe mount I typically print at about 80% infill. But again I can try going as low as 10 - 15% since the gear bearing doesn't exactly need tons of structural strength to it.

80% infill will pull your part a lot. For gears I go 60% max and never had problems.

A customer once ask me for a 100% nylon print and was impossible end up making it 80% and it was a pain.

I have my bed at 90c printing pla or petg, I put 4 layers of pva straight on the aluminum heat bed, not a tiny lift on a 3hours print, even at 80% infill. Could it be your bed temp is inaccurate? Think mine reads higher than it is anyway. Nozzle temp depends on printing speed I'm at, between 190 to 220 on pla and 230 on petg but I always do petg slow with highest layer height possible for transparency but keeping water tight.

Over extrusion at first few layers can also result the same.

Edited 2 time(s). Last edit at 06/16/2016 05:31AM by deaconfrost.