The heating and cooling time is roughly the same as the aluminium bed. Cooling is about the same too.

I'm considering rewiring the heater if the bed to up the wattage so it heats faster but then I'll need to have a bigger power supply.
Not a problem as such (I have a bunch of spare server psu units that can deliver many more amps than is needed) it's finding the time that's the problem really.

I'm happy enough with the cool down time I rarely print things back to back so generally start a print when I get in from work and then turn the machine off a few hours later and go to bed, hence I don't care how long it takes to cool. But if I really really want a part in a hurry it's only ten minutes or so until the part can come off.

It's far easier to have a removable media, that you can swap out and continue printing almost immediately.  With the stock bed you have to either pry the prints off or wait til it cools enough to easily remove it.  Plus, you risk tearing the kapton on the bed when prying the prints loose.  With the removable glass, you have the ability to do multiple prints in short order. 

I like Danny's solution, but I'd have to have something with a connection for the glass so that I could swap out panes.  Other than that, it's elegant and works well.

Danny, how fast does the bed cool to remove the prints?

http://www.soliforum.com/post/6825/#p6825

I imagine that cutting could be done with an ordinary diamond tile cutting wheel, I've completely replaced the Aluminium bed with a 1/4" sheet of glass, and drilled that happily with ordinary tile drills.

I'm not sure thats a good idea. Without the Aluminum, there is no heat spreader for the heated bed resistor.

The part number is 8476K161 and it cost me something like $13 for each.

I have not had a chance to print with it yet, but I will soon.

ERrr....you had pieces of glass stuck to your part? That seems really remarkable for glass to flake like that. Are you removing your parts very aggressively?

No, not at all, it usually just happens during cooling down so it's pure thermal shock. The glass kind of delaminates. It's not dangerous but then the piece of glass is useless to print on. But it was cheap (IKEA) mirror glass, I'm not surprised of this effect.

I use $2 2mm glass. Haven't noticed flex, but if I upgrade my bed I'll move to 3mm just to be sure.

I'm currently printing on (very cheap) 3mm mirror+kapton tape... I had issues with thin layers of glass remaining attached to the print, hence the tape.

To do things properly, you should use borosilicate glass, and this is what I'll do next. It can be cut at home and it's very resistant to heat shocks. I haven't heard of tempered glass being used as printing bed, I guess mostly because it's difficult to manufacture and cut.

I second the borosilicate

To do things properly, you should use borosilicate glass, and this is what I'll do next. It can be cut at home and it's very resistant to heat shocks. I haven't heard of tempered glass being used as printing bed, I guess mostly because it's difficult to manufacture and cut.

Currently happy with 3/4mm.