You aren't heating the glass unevenly, or just one area because you are using a heat spreader, some heat difference is acceptable, it's not going to break because of a small difference.Quote
AndyCart
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sheepdog43
Endstops are ignored while printing.
If you plan on only heating one area, it will need to be boro, otherwise you will break the glass.
Not necessarily. I have a similar setup on one of my core xy machines. I use a 200 x 200 MK2A heat bed pcb but my glass bed is 300 x 300. I have a piece of 1mm aluminium sheet between the pcb and the glass and the glass is held in place with bulldog clips to allow lateral expansion. The glass is normal 4mm window glass and has dozens of hours of print time with no issues.
I run it at 70 for PLA and 100 for ABS. The bed edges I.e not directly over the pcb are cooler than the centre but the aluminium helps even things out a bit. At 70 in the centre the edges are around 60.
Andy
He was wanting to heat only part of the glass and leave the rest cool.
And yes, the endstops do need to be configured that way in some firmware, but not all. In some cases it just may be a matter of it being set by default, others just do. I don't remember even seeing an option for it in Smoothie.