So, this is what hapens when you leave the bed at 150 degrees celsius.
I’m sooo stupid. To speed up the heating process, I had set the bed to 150, but forgot to change it back to 80 as I should have.
To be honest it’s probably the four binder clips on each side not the heating of a glass that took it out 
If there’s any way you can do it… print some abs clips that have a little bit more give than those binder clips and you’ll probably never break a piece of glass again
I use silicon thermal transfer pads…no clips of any kind
@Eclsnowman The binder clips have been there for years. Never a problem. But thanks for the suggestion, it is something that is on my todo list, but never got to really do it.
@funinthefalls , I probably have the wrong thermal transfer pads in mind, but to me that suggestion sounds awful. Unless you know where I can get a 400 x 400 silicon thermal pad? affordable?
Why should a setting of 150°C heat faster than a setting of the actual needed temperature?
@Rene_Jurack I as wondering the same. It’s not like a car’s automatic climate control for example, where the system works harder (and noisier) if it thinks it has further to go to get to the desired temperature.
Yeah, it will get you there a little bit quicker at the cost of a major overshoot. If the heater control starts turning off too soon, you’re better off adjusting the PID settings a bit and setting the correct target temp.
Saving like 10 seconds 
@Rene_Jurack probably right, 10 seconds or so, but I was in a hurry. As I already stated, just plain stupid.
@Jeff_DeMaagd um yeah thats 2 seconds in difference. And if you think correctly it even didnt get you “there” quicker. It gets you too far xD
@Mark_Wheadon that are just the fans that blow the air. At least in cars since the late 90s that heating and cooling of your car should work just the same as a heat bed. The radiator of you car is mostly at 95deg and the compressor for cooling ON. Its just regulating the right airtype.
All you need for silicon thermal transfer pads are 2cm x2cm x .5mm pads spread over about 30% of the bed area. You will get clean even heating with no warping of the glass caused by clips.
It really depends. I did once have an auto tune that yielded me a setting that would never quite get to temp but permanently hover just enough below that Marlin would not start the program. But as I noted before, changing the settings fixed that.