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I've got a glass box that measures 900mm x 450mm x 450mm.

The width of the glass is 6mm thick.

If I drill, cut, or grind a small hole in/through one of the faces; will it significantly affect the structural integrity of that piece of glass?

I'm concerned it might become prone to cracking, if for instance, I pick it up to move it.

I thought there might be some kind of ratio, or formula I can use to determine a safe size for a hole, a safe distance from the edge, and so on.

glass box schematic diagram

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    $\begingroup$ Yes, search for Stress Concentration Factor for hole in plate. A rule of thumb is that the strength is at least 1/2 of the original strength under the same loading. $\endgroup$ – John Alexiou Jun 4 '17 at 17:09
  • $\begingroup$ and just to add, it will also depend on where the hole is : centre, edge etc and also the internal loading - is it just air inside ie a display case or a fish tank full of water... $\endgroup$ – Solar Mike Jun 5 '17 at 7:51
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    $\begingroup$ The estimates for stress concentration factor assume a smooth surface. If the hole is created by grinding or drilling, thus creating a huge number of surface defects, the strength of the sheet could be reduced to zero. The relevant field is fracture mechanics. Glass has a relatively low fracture toughness. $\endgroup$ – Chemomechanics Jun 5 '17 at 15:40
  • $\begingroup$ So you have a 100 gallon aquarium. The bottom and possibly the sides will be "tempered glass". Tempered glass requires special techniques normally left to professionals. There are a great number of aquariums with holes in the bottoms and sides that hold water and gravel ( combined weight ca 1000 lbs for your size). Are you going to put more weight than that ? $\endgroup$ – blacksmith37 Jun 5 '17 at 21:43
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    $\begingroup$ Just as an aside, your figure is extremely over-dimensioned. It really only needs 4 numbers to completely define the geometry: 450, 450, 900, and "90 deg TYP". It would be much clearer that way. $\endgroup$ – Mark Jun 6 '17 at 1:33

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