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21 votes
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Fracture patterns in tempered glass

It's an artifact of production - in particular, the construction of the conveyor belt of the machine performing the quenching process. The pattern can be observed through a polarizing filter in the ...
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15 votes
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Why doesn't stovetop glass crack from thermal shock?

Stovetops are made of glass-ceramic which has extremely low thermal expansion, hence no cracking from temperature change. In fact, the coefficient is with $0.1 \cdot 10^{-6} \ 1/K$ even lower than ...
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6 votes

How would I put a barcode of other scannable code on a coffee cup?

A few different marking processes are available to accomplish your objective. Glass is a good choice, for reasons of durability. Etching One creates a mask or stencil with the desired graphic. In ...
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4 votes
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Feasability of glass gears?

the tooth-root stresses in a gear are tensile and the teeth roots have sharp corners. This means if the glass gears were carrying any sort of load, the teeth would shear off right away. Furthermore, ...
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4 votes

Why doesn't stovetop glass crack from thermal shock?

It doesn’t crack because it is the so-called Pyrex glass. It is not the same glass as common window glass which is still silica, but blended with sodium and calcium. Pyrex is silica blended with boron,...
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4 votes

Why doesn't stovetop glass crack from thermal shock?

Borosilicate glasses (e.g. "Pyrex") have small coefficients of expansion (about $3.3\times 10^{-6}$/°C compared with $10\times 10^{-6}$/°C for steel) and can tolerate temperature ...
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4 votes
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What does TIR stand for in Window Pane Fenestration?

TIR: Thermal infrared (longwave) transmittance of the glazing layer. Lawrence Berkeley National Laboratory has a windows program called THERM 6.3 / WINDOW 6.3 NFRC Simulation. In pp 55 of this manual, ...
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3 votes
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How can a small screen be projected on glass but still visible near 2cm from eyes?

When you project an image on a reflective medium, you inherit the projection distance. So what you are seing is a plane that is hovering behind the glass. In essence your eyes see is the whole path to ...
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3 votes

Feasability of glass gears?

That's only a good idea if the gears will be rotating very slowly with almost no load. Gear teeth undergo significant tension and compression loading, something glass is not good at handling. Would ...
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  • 2,402
3 votes

Usticking two glass elements fused by vacuum

Perhaps, depending on the materials, you could try gently heating one piece while cooling (or at least heat-sinking) the other piece, and hoping that the expansion mismatch will separate them. You ...
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3 votes

Tempered glass physics

Tempered glass resists fracture because it is manufactured in such a way as to place its surfaces into a state of residual compressive stress. To cause it to experience brittle failure in tension (...
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2 votes
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Glue plastic to glass with chance for easy removal later

Because the surface is a windshield and because you wish to have it somewhat removable, consider Solar Mike's suggestion of double sided tape, but add in a parameter for outdoor use. 3M makes a great ...
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  • 6,092
2 votes

Laser beam welding

Most weld optics have a protective glass that shields the (more expensive to replace) focusing lens from welding spatter. So there are definitely glasses that exist and can be used for this. When ...
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2 votes

Tempered glass physics

By definition, "tempering the glass panel all the way through" is not possible. The interior and exterior parts of the glass must have different properties. Tempered glass is made by cooling the ...
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2 votes

Database for stiffness matrix?

The material has to be tested for each application as the fibre density, weave and number of layers all have effects on the stiffness. This means even each batch may have a variation so exact values ...
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2 votes
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Glass Facade Load on edge of slab?

The value of the distributed load is trivial to determine: it is equal to the linear weight of the glass. The linear weight is itself equal to the product of the thickness, height and specific weight ...
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2 votes

How to cut a thick glass block at home?

Here is one way, used to drill holes through the plate glass wall of an aquarium. Imagine a thick brass shim. we cut slots along one edge so that it looks like a saw blade with oddly square teeth. We ...
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2 votes

Alternative to high cost plexiglas and polycarbonate for large project

If you have the ability to cut glass in the manner required, thereby saving those costs, you can find rear projection televisions that are being tossed out. I have ceased looking for them, as I have ...
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1 vote
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Safety of fiberglass, cloth

Fiberglass is used in specialty clothing already. Cut resistant gloves for instance. Also for thermal protection for welders, fire fighters, and lab rats. https://www.auburnmfg.com/product/ami-flex-...
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  • 3,381
1 vote

What is the ideal gap between two panes of glass for insulation

There are many factors, but intuitively the gap should be adequate to allow a decent thermal gradient for the air. Air can establish steady convection, rising on the room side pane and descending ...
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  • 20.9k
1 vote

Mirror without glass?

I just noticed "mirror" was actually created by applying thin layer of metal on top of glass. The vast majority of modern mirrors are created by applying a thin layer of metal to the back ...
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1 vote

Feasability of glass gears?

Another point, that hasn't been mentioned: Over the time you will have some wear, which means scratches on the surface. These scratches can be starting points for cracks. That's why gorilla glass uses ...
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1 vote
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How much an unevenly heated glass plate bows?

You are right that your numbers are over-estimates. They would be "correct" for a plate with no resistance to bending, which was only supported along two edges and heated across its full width between ...
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1 vote

Seperating two glass pieces with a circuit board inside

You can cut it carefully with a hacksaw with fine tooth blade while it's held in a vise. Or cut it with a small grinder held in the vise, using a tablesaw guide.
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1 vote

Usticking two glass elements fused by vacuum

Vacuum bagging is used in the creation of various items, including and especially amateur built aircraft. A suitably strong surface holds the item being bagged. Plastic film is placed over the item ...
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  • 6,092
1 vote

Need Help to Remove Sway from Steel Post + Glass Panels

Make the post go from floor to ceiling just like the one on the corner. It won't sway.
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  • 401
1 vote

Need Help to Remove Sway from Steel Post + Glass Panels

You may not see it but the vibration is slowly loosening the base support, compromising waterproofing, cracking the slab and causing many other damages. As you may have seen in glass guard rails ...
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1 vote

Automatic tinting of a region of glass

Glasses that change color with external stimulus (smart glass) are usually laminate structures in which the glass itself is not the active component that generates the change in color or transparency, ...
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1 vote

Glass used in biometric machines

According to this glass manufacturer it is more about the optical properties than mechanical ones. They are looking for: Homogeneous illumination of the touchsurface Transparent and durable in UV and ...
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1 vote

Methods for cutting glass

Waterjet cutters work like a charm up to 5mm. I have cut 'fireproof' glass of 4mm and it came out very well.
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