It puzzles me why people use heated beds when printing with PLA or PETG. When I first got my printer kit the pre assembled bed MK2 came covered with blue painters tape. I started with PLA and could not get it to stick, tried glues no luck until I got the proper nozzle to bed distance correct then things started to stick but the aluminum plate was uneven high on edges low in middle like Detroit streets made leveling a chore prints would be squashed on one side delaminated on the other. So I got a 1/4 inch glass plate and covered it with blue tape and printed on it made a significant improvement but had to rip tape off to get parts off still a little warped found that bed level was changing during the print caused mainly from Z axis motor couplings springing open and close fixed that issue bed now stayed level. But then the blue painters tape new each print would bubble or lift off the glass in spots another uneven first layer squashed deformed mess.Solution was ditch the tape go directly to glass but parts were like newbies playing ice hockey sliding all over some said heat the bed just made the ice melt and current draw stole from steppers and nozzle. Get a bigger power supply…forget about it ! I used some Elmers School Glue in a stick and rubbed on the glass and now the first layer is smooth and sticks to the bed use a razor blade to gently tap parts off the glass. Now I print with PETG and never use the heated bed until I change to other filaments at which time I will get a separate power supply for the heaters. To sum it all up a LEVEL bed and NOZZLE distance is the most crucial aspect to first layer problems get that right or buy a coloring book. Some say I have auto leveling and while that may work well it is a software solution to a hardware problem for quick settings relying on inductive,capacative or photo electric sensors but you should learn how to manually adjust the bed and nozzle when auto fails. That’s my story and I’m STICKING to it.
Heatbeds help enormously with permanent print surfaces like PEI. And even PLA and PETG will warp if you make a big enough part or have a cold room.
I use hairspray and a heated bed for PLA for a few reasons. If I don’t use the heated bed, the corners of the print curl, I can get around that by using printers tape but then it’s a pain to get off. I can also get around that by using glue stick but then it leaves a surface texture that I don’t like. So it’s hairspray and a heated bed for me. It works and so far, using this combo, I haven’t have one failed print related to bed issues i.e. Slipping or curling
Lots of people rely on chemical or mechanical grip nowadays. I just don’t see any reason to print abs over my pla which is why I don’t have a heated bed. I use hairspray and it usually works but sometimes I am left worried that large parts will separate, or parts with small surface area.