Type of Glass for Print Bed?

[intohim]

I was wondering if anyone could let me know if heated print beds typically need any sort of specific glass, or is it mostly thickness that is important? If I need to replace my glass bed, can I go out an buy any type of glass, or use a mirror I have in my home?

[old man emu]

Any type of glass will do. All it is used for is to provide a smooth surface to print on.

I went to a $2 shop and bought a cheap picture frame. Luckily I have a good glass cutting tool and know how to use it.

What's strange is that the picture frame cost more than $2. False Advertising!!!!!

Old Man Emu

[Davo]

I just get replacement glass from the home improvement or hardware store.

[Roxy]

The thinner... The better... It will heat up quicker! Especially with thicker glass you will see a difference between what the thermistor sees as the temperature and what the top of the glass is at.

[3dkarma]

Picture-frame glass isn't that great for use under heat and tends to break into nasty sharp shards. Use borosilicate glass if you're worried about the safety side.

[atoff]

Picture-frame glass isn't that great for use under heat and tends to break into nasty sharp shards. Use borosilicate glass if you're worried about the safety side.

Hm, yeah, I was just going to say, it's typically borosilicate glass that's used. You'd want something that can handle the heat and stresses.

[awerby]

3DKarma is correct; it's much better to use borosilicate (one brand name is Pyrex) than window glass, because it's more heat-stable. Lulzbot will sell you a sheet of borosilicate glass even if you haven't bought their printer: http://www.lulzbot.com/products/boro...d-300mm-x300mm

Andrew Werby
www.computersculpture.com

[KDog]

I've been using mirror tiles since I started. They are 3mm thick and I've never broken one. I've never been completely clear about the "borosilicate" glass and why it is any better than what I use. Heat-stable? I don't think that even matters at 100C. Maybe at 1000C. What is the difference in expansion in a 3mm mirror vs. a 3mm borosilicate? Even though borosilicate has like 1/3 the expansion coefficient, what are we talking about in real numbers? Will the differences between the two make any difference at all if you set your bed height after everything is heated up? The math is a bit beyond me now but somebody please give it a go and let's talk about real numbers. Borosilicate glass is expensive....maybe that's why vendors want us to buy it? I think it is all gimmick.

[old man emu]

Consider this:

Manufacturer A produces a 3D printer and sells it without a glass cover for the heat bed, saying that the sheet of glass is likely to break during transit. The manufacturer tells the purchaser to simply obtain a sheet of glass of suitable length and width to cover the heat bed. The manufacturer does not give thermal specifications for a suitable glass.

If you were the manufacturer's product liability insurer, would you ask your client to show that the advice given freed the manufacturer from any liability?

Old Man Emu

[RobH2]

Anyone know were to get borosilicate glass that will fit a Makerfarm, 222mm x 222mm (max)? I've tried to special order it locally and they want $100 per. Window glass is working just fine given that cost. But, borosilicate glass has a lower expansion coefficient than normal glass and that helps part adhesion. I'd like to try some but I just don't want to spend $100 on it.