I’m having a new problem on my PrintrBot Simple: Curling. This is the largest print I’ve attempted, taking up most of the build area. It seemed I had to go a bit hotter to get both filaments to extrude reliably.
I tried printing in Coex red PLA, 210C, 0.3mm layers, 50% infill, fan on, and got terrible curling at the corners, pulling up the blue tape.
I tried again with PrintrBot natural PLA, 200C, 0.3mm layers, 10% infill, with an additional desk fan blowing on the part, and still got curling at the corners.
What am I doing wrong here, folks? Maybe because it’s about 10F cooler in here than it was when I printed my last large item (about 75% size of this one)?
I have been having similar issues as of late. I usually print on my workbench in the garage where the ambient temperature is ~ 60F. When I installed the metal print bed on my simple I noticed similar curling issues to the ones you are having, even on smaller prints. In my case I think it has to do with the fact that the metal print bed is much colder than the wood one was and the material is just cooling down too fast.
What is the ambient temp in the room where you are printing? Do you have a metal or wood bed under the blue tape?
Try setting a brim in your slicer. It increases the surface area when printing with the hopes that that will lift a little as opposed to your part. Also, is your tape fully stuck down on the bed there? It looks to have lifted a little in the middle.
Brim.
Just a stab in the dark, but as it is such a large piece, maybe try not turning the fan on for the first few layers?
Wipe the tape down with isopropyl alcohol to clean off the wax that they put on there. You’ll probably have trouble getting it off after that 
I add some rest and increase the bed temp by a couple of degrees
Another vote for adding a brim. Its what I use with abs and I have had no trouble after adding it!
Boroscilacate glass, brim, done!
Alcohol + brim
I find that fresh tape works best, a brim as everyone as said. Then a bit of over extruding on the first layer
@Christopher_Benjamin glass without a heated bed is more difficult I have heard.
Set first layer to 220-230 without fan, run first layer at 20% speed (yes, really slow), turn on brim. Alcohol prep the blue tape.
I’ve gotten parts to stick so well to the blue tape that I had to remove it with a razor scraper, but the warping pulled the tape off my glass build surface. The only fix for the parts I was printing was a heated bed.
After removing your existing tape, clean the bed with isopropyl alcohol. Once clean, use a hair dryer and heat the bed up (not hugely, just warmer than body temp) prior to applying the tape. Apply the tape and then clean the surface using isopropyl. Then heat up the bed (with tape applied) again with the hair dryer, then start your print. Hopefully it’ll keep enough heat for the first few layers to bond well.
Also: I find scuffing blue tape with very fine grit sandpaper (eg: 1000+ grit) after cleaning makes it a lot hairier, which makes the plastic hold better.
I have heard that a microwave therapeutic neck wrap type object works well for the purpose of hearing the bed.
Thanks for all the suggestions!
I’ll try the brim, though I don’t have much room for one on this print.
I’ll also clean the glass I have on the print bed, then tape, then alcohol to try and get real good adhesion of print and tape.
I’ll keep the fan off, and heat up the first couple of layers. I may even try heating up the bed with a heat gun (no hair dryer; no hair).
I’ll let you know how it goes.
Outside of what has already been suggested, you may also want to exaggerate the first layer in slic3rs advanced setting. When youve calibrated well for low layer heights, sometimes that first layer thins out. Its set to 200% default so fudge that number up or lower your extruder nozzle till you get the best results. I personally print at 130%-150% on the first layer.
Curling of PLA plastics are mostly due to shrinkage caused by uneven or rapid cooling. Getting the temperature to drop slower and more evenly. I would too suggest a warmer bed and perhaps lowering fan speed or distance if it’s not variable. I believe that even enclosing much of the build space helps control ambient temperature which is why many market production models are as such not just for aesthetics. It isn’t just about keeping it stuck down it about the the re-crystallization temp of PLA.
@Christopher_Benjamin but he doesn’t.
Maybe try rafting, I do this in cura, it works well.