So on Facebook I asked

There was a discussion about print bed leveling and how to fix it but a question came to mind. It was not answered on Facebook.

What actually is the flattest surface available for printing?

My first thought was glass but I have never use glass.

It’s certainly difficult for glass to not be flat.

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Lol that’s the best thing I’ve heard today

Guess it was an illegitimate question…

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No glass is pretty flat lol I would also guess pei buildtak?

I just meant that if there is something on the machine that will make a flexible plate not be flat then glass would not bend so easily and stay flat when everything else is moving

I love glass because it’s always level if you get good glass the creality glass seems to be really true and level I personally have never had a bad piece of glass from them. also if you over tighten your bed springs you can bend the corners in causing the middle of the bed to be higher than the outside corners and warping your aluminum heat plate

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If glass is “poured” it actually has to be flat, but only on the top. The bottom is only as flat as the pour table.

Actually modern commercial made glass is poured onto liquid metal, usually lead or tin, so that it’s stays flat no matter what, at least for a few hundred years.
Glass is actually an amorphous solid, so it’s not technically a solid, more like a supercooled liquid. It’s just moving so slowly its takes hundreds of years to deform.

And that’s just freaking cool.

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Very true, If you actually see OLD glass windows they are thicker at the bottom then the top cause the glass is actually running down due to gravity.

Worst I’ve seen was in an ghost town in AZ, the glass opened about a 1/4 inch gap at the top of the window and was paper thin, at the bottom it was overlapping the wooden strips used to hold it in place.

Had a picture of it on an old cell phone but cannot find it now.

I did not know about them pouring modern glass on liquid metal. That is a really cool process.

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Yes,
“Old Glass” was spun and cut to size.

“New Glass” is floated on molten Lead or Zinc!!

I’ll see if i can find you some Youtube’s about it.

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New:

This video says “molten Tin bath” Periodic SN #50

Old: I can’t find a video where the Mouth Blow the Glass and Spin it like the old buildings use to have
https://www.google.com/search?q=Old+spun+glass+windows

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