Glass bed?

This may have been discussed before or somewhere else, but I didn't see it when I glanced through.

I have been using regular untempered glass over my bed and I've just went through my third or fourth piece (in about a year). I was just curious if there was a certain vendor for tempered glass or alternative option that those of you with more experience would recommend?

Thanks!!

Gone through them in what way?

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Waitaki 3D Printer

Broken them, due to the heat mostly (though I did drop a stepper on one of them.. but that's not overly relevent).

Well they shouldn't break with heat I would have thought. I use bog standard glass from my local glazier and never had a breakage. Is your glass laying dead flat and not being stressed in some way?

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Waitaki 3D Printer

Untreated glass can break under thermal stress. That's pretty common knowledge, I thought. Especially when affected by a fairly quick change such as going from room temp to ~80C or more that is typically used for the heater bed.

But, for my setup, the glass is not stressed. It is supported on a set of screws on the base with a gap between it and the bed of like 1cm.

A borosilicate glass will resist thermal shock. Many have used good quality window glass but many of us use borosilicate. I use Schott Borofloat brand but there are others as well. It can be 5-10 times the cost of regular float glass. If you are using a standard driver board set up (mosfets and 12 vdc) it's not likely the temp will change quick enough to break good glass but there is also an issue of how consistent over an area the glass is heated (and subsequently cooled). For the most part at these temps borosilicate is immune to this sort of thing though using a good heated bed with consistent heating will go a long way to getting regular glass to perform well.

Cheap mirrors - [www.reprap.cc]
Carbon fibre [www.reprapsource.com]
PEI plate [www.reprapsource.com]
tape covered polycarbonate works too.