warp free large prints
I recently purchased my first 3D printer a Mk4S ...it's been great for small parts but i've been having a lot of problems with larger parts warping.TLDR Parts not lifting but Spring Steel sheet "lifts". my solution - 1/8 inch G11 "Garolite" on spring steel + Nano adhesive
Being a newbie i spent countless ( undoubtedly misguided) hours trying to eliminate warp and it was made even more difficult and expensive because i really wanted to be making mechanical parts in PC Blend . So i found, not surprisingly, that with PLA i could get a pretty good resuilt just by focusing on bed adhesion, with mouse ears brims and "glue" . When i moved to PC Blend , i had (as expected) more warp problems. I was using the satin sheet and the corners of the prints were lifting even with large mouse ears, brims , thin perimeters etc. I tried the smooth pei sheet with glue and the part almost didn't come off the sheet, all the corners were solidly attached to the sheet ...BUT when removed, the part had a domed shaped bottom and mostly flat top, Bottom corners were off the surface plate by 1.5 mm. I finally realized that the problem was the PC shrinkage was powerful enough to partially lift the spring steel print sheet. So next attemp was PC-CF since it's suposed to be isotropic. I used Maggigoo PC instaed of Glue stick on smooth PEI. Better, part stayed on sheet and was fairly easy to remove, but still at least .5mm of curl . I went in search of a solution. Since the MK4S has a load cell for bed leveling ... i used an 1/8 inch "Rigid" G11 (garolite) sheet with a Spring steel backer i got on Etsy from Holden Enterprises....no printer adjustmenst required ...it just worked. I wasn't sure how the PC was going to adhere so i used Nano Adhesive. The part (about 100mm square) is flat as a pancake as measured on a surface plate. I am using the Prusa Enclosure , PC Blend stock settings, but with bed temp cranked to 120C ( that gives an actual bed temp of close to 100C) . .2mm structural but with perimeters =5 and 30% triangle infill. The enclosure is psuedo temperature controlled at 45C with a 200 watt light bulb (had a hard time finding this obsolete tech) . There is a very very small fan (3CFM) that exhausts to my garage attic. The rigid plate does still flex just a tiny bit and that's useful in getting parts off the garolite. the only downside to the thick sheet is it take a long time to actually get to temperature. I am loving the Nano Adhesive ...expensive, but a lot cheaper than replacing print sheets...and it is so much more convienient , very easy to apply and no constant alcholol prep. I have done at least 15 prints of good size parts PETG on PEI smooth sheet with out any "maintenance" of the coating. i'm not even that careful with regard to fingerprints ....no issues. The parts stick while hot and pop off after the sheet has cooled. As always YMMV. As i gain more insight into making flat mechanical parts i will add to this thread if there is anything new. I suspect there are a bunch of other possibly simpler solutions to the spring steel sheet lifting.