How to cut a glass tabletop - GIF

[Jon]

How to cut a glass tabletop. Not sure if I would fear more for my back, or my eyeballs.

[Toolmaker51]

How to cut a glass tabletop. Not sure if I would fear more for my back, or my eyeballs.

Not to mention cleaning up the scrap pile. Yikes!

[marksbug]

looks like a boring job with glass.....not for me.

[Jon]

[Toolmaker51]

Interesting production ballet, well planned execution. Those men might be paid piece rate, or are the company proprietors.

Or, it's baseball season in the neighborhood...

[CharlesWaugh]

They have to go that fast because they have already done the vertical scores on the glass (note that the guy in black breaks it over the edge of the table then also cross-wise in his hands before putting the two pieces in the stack).

Speed is important, because the cracks that the scoring tool makes quickly begin to heal and then the break gets ragged or even runs off-score, making a terrible mess.

At least, that's what some 'old boy' window glass guy told me - it makes sense. I also seem to remember some Scientific American article about crack porpagation and self-healing of glass, but I can;t find it with a quick search.

[Frank S]

My grandpa always told me when cutting glass only make 1 score and don't dilly dally around or the glass will break uneven. He always used the ball end of the cutter underneath the score line to propagate the crack in the right direction.

[jasp93]

Glass does “creep” or flow but the process takes years, if not decades
The question of rapid “healing” is absolute rubbish - a minute or two, an hour or two etc etc etc makes no difference.
Cutting glass is all about a very fine scratch and confidence!
Jim P

[CharlesWaugh]

No, it's not rubbish:
https://www.lehigh.edu/imi/teched/Gl...5_Hermanns.pdf

See page 11 of the presentation (keep in mind these are simply powerpoint slides, not the full lecture, so it's just the very highest of the high points)

I remember reading a Scientific American article ages ago about this, but I don't have access to searching and finding that article (paywalled).
The micro-cracks self-heal, and the oil on the wheel gets in the cracks and keeps them open.

But, in everyday real-world life, no big deal.
:-)

[mklotz]

A good deal of the hocus about glass flowing arises from the observation that many cathedral window panels are thicker at the bottom than the top. This seems to indicate gravity-induced "flowing" until you realize that just as many panels are thicker at the top than at the bottom. Then there's the problem of all that ancient Roman glass that, despite sitting around for millenia, still hasn't flowed.

For a more detailed discussion, read what the Corning Museum of Glass has to say about it...

https://www.cmog.org/article/does-glass-flow

That said, my great uncle used to do all the glass work for a major hardware store in Allentown. My Dad and I often visited to watch him work. He frequently spoke of the need to make the break quickly after scoring the glass. I'm inclined to believe that his concern (and that of other glass workers apparently) was genuine but due to some other physical effect than the glass "healing".