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How to cut a glass tabletop. Not sure if I would fear more for my back, or my eyeballs.
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Not to mention cleaning up the scrap pile. Yikes!Quote:
Originally Posted by Jon
looks like a boring job with glass.....not for me.
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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...
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.
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.
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
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.
:-)
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".
I'm not so sure if it is the self healing or the migration of micro fractures caused by the cutter. A pressure wave is created in the pane of glass when scored this wave needs to get relieved as soon as possible otherwise the micro fractures might create larger fractures.
Not sure if this is the reason but there is a high plausibility IMHO.
I semi apprenticed under a master glass guy over in Berserkly for a year off and on, making Tiffany style (foil wrapped) stained glass which typically is not flat or even thickness and breaking that stuff quickly is imperative. The glass composition itself has a lot to do with it as well as temp control. He made much of the glass we used with techniques that were beyond me at the time. He eventually migrated into making 14-15th century blown glass miniatures and worked in Iran just before all heck broke loose teaching the next generations glass making...got out just under the wire.
safety glasses ?
SURFs UP! Duck season?Quote:
Originally Posted by Toolmaker51
those guys are well experienced at it and the perps are done before video, as stated elsewhere. Maybe the speed has been enhansed as an accident at that rate, is a strong possibility.
My experience cutting framing glass ,mostly 2mm, use a minimum oil (like wetted carpet) to rub cutting wheel (or edge) over for lubrication to lengthen the life of the cutter & causing lubrication on the very hard surface. As for runs: they usually dont occur if the glass is scored from end to end. I used a technique where I started about 6mm (1/4") in from start end and go back to edge & then forward to other end & all this only takes a couple of seconds at most. Phone calls after score & before break, didn't affect the outcome. the ball of the cutter can be used to gently tap the slightly lifted panel though I preferred special glazing pliars to cradle the score, lift & clamp=snap=perfect break. ALL relies on original score. I've seen more experienced guys do it without a full score but sometimes the unfortunate happens.
Several decades back one of our kids scratched a mirror. We are still waiting for it to heal.Quote:
Originally Posted by jasp93
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a cut above the rest.
???
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??? x 2.Quote:
Originally Posted by Jon
I agree.
Where are 6" disks of fragile thin glass used in that quantity?
And where are the discs being thrown, where at least they're not breaking against each other?Quote:
Originally Posted by Toolmaker51
And the sleeves? Is that safety gear; but what about the grommets?
And gloves/sleeves PPE, but no eye protection?
And the wagon wheel cart?
Picture frames, clock faces etc.
Tony Foale says picture frames, clocks. . .highly likely. Never thought of them; looking around nothing round at home like that.Quote:
Originally Posted by Jon
I think the grommets are just vents, the worker [she?] uses coated gloves nice nonslip grip. Safety glasses would be common elsewhere; glass is thin and light and little stored energy, not too close to face, but still.
That volume is probably going right back on a conveyor to assembly, spaced by rate they're separated from strip.
The cart is scrap, as the barrel fills.
If I had to guess where the disks are used I'd say dollar store picture frames?
looks like he is throwing to his old buddy nub so he can set them in the frames.
My vote would be the next step would be to grind the edge then placed in an oven to soften the glass to allow it to be shaped into a slight dome. I have a clock with a domed shaped glass just about that size. Also the picture frame comment is a good one.
Make a visit to the house of frames and you can find any number of round or oval shaped frames both with flat and domed glass
clock faces, picture frames, bottoms of bell jar display cases are the ones I thought ofQuote:
Originally Posted by Toolmaker51
[QUOTE=Toolmaker51;133623]??? x 2.
I agree.
Where are 6" disks of fragile thin glass used in that quantity?[/