Petg warp

Hi all, I’ve got 3 hours left off a 12 print, I’ve noticed a corner lifting, looks like warping, using petg, temp 239, bed temp 80, z is 0.10, done several prints with no problems at all, my printer is in a heated workshop, the out side temp is minus 2, I have no box over the printer, do you think it could be the draft when I go to check on my print, regards Andy

Did you a proper pre heat? If not the outcome is random. It is as easy as that.

The problem is that you (hopefully) calibrated the printer hot. When you start a print, then you don´t meet that same criteria, as the printer is cold. The bed may be at 80°C, but the frame, the springs and stuff are not. When calibrating it usually takes some time and the printer needs this time to heat through. The thermal expansion needs to kick in everywhere and not just at the bed.

If you start printing the z distance will change during the first and second layer due to that thermal expansion. This is also why a second attempt to print something usually sticks better as the first attempt was used as the pre heat phase. The printer has soaked in more heat into its skeleton like the bed leveling springs and screws and the under frame, while on cold start this is not the case.

This is the most common mistake. The preheat functions are there for a reason and this reason is not to calibrate a printer. Just turning the printer on and start a print is like playing in the lottery. It may work, it may work a little or it fails. You only get consistent results with preheating.

People spend so much time and money in upgrading the build surface to something that “sticks”, but actually it does not matter as much as simply do some minutes of pre heating.

Yeah, just leave the printer running hot for around 10 minutes before starting a print and you should be fine.

Well, you need to level the bed. That is usually done with a piece of paper. You also need to set the distance between the bed and the nozzle.

All those operations should be done, while the printer is fully heated, to get a proper “while printing” result, which will be the same every time. Well, every time you preheat your printer to meet these criteria.

That is what I ment with calibrating the printer hot.

Hi there, as you can see, I have a bit off warping at this bottom corner, I cleaned the bed, pre heated for a good 10 minutes, leveled the bed when up to temperature with a sheet off paper, used magigoo, I’m using petg, do you think it would be a good idea to use a box over the machine to retain the heat, thanks for any advice Andy

Try raising the bed temp to 85C… that’s what I did.

Will do, thank you, the print stayed OK, a little nerving on a 10 hour print, thanks again