# Tempered Glass Tabletop - Safe dimensions for a given base?

Sorry for the confusing title. We have a circular table (an old etched wheel) that is 3ft in diameter. It also has 4 rubber spacers along the diameter. I want to get a tempered glass tabletop for it. Our old one broke when someone placed a hot dish on it. The old glass had around 3ft 6inch diameter and about quarter of an inch thick.

My question is this: Would a 12mm thich, 4ft diameter tempered glass tabletop be safe?

Our table would end up having a 6 inch glass ring around our current table. Would that be safe for dining purposes?

Here is a photo of the table and a photo of the rubber stoppers.

• What were the dimensions of the original surface? Jan 12, 2016 at 22:22
• Hmm. The firsr glass we had was about 3ft 6inches in diameter. Jan 12, 2016 at 22:23
• ... and how thick? Jan 12, 2016 at 22:41
• Around a quarter of an inch thick. Jan 12, 2016 at 22:42
• So, half the thickness of your proposed replacement. (Would be good to add this to the question.) Jan 12, 2016 at 22:43

If you use only four support points, your glass top is actually sitting on a square about 2.12 feet on each side. So your overhang for a 4 foot circle is about 11 on each side.

Tempered glass is very strong (note that annealed or hardened glass is also strong, but much less so than tempered). This calculator suggests that a 1/2" tempered glass shelf 11" x 25" supported at the ends would withstand a weight of over 600 lbs. The pressure on your table edge is somewhat different, since it is supported only along one edge, but that edge is attached to the rest of the top. It sounds as if there is little danger of the unsupported edge breaking off.

The bigger risk is tipping. If someone leaned on the edge of the top in between two of the support points, you have a lever of about 1 foot lifting three fee of tabletop. The top would be quite heavy (maybe 80+ lbs.) and would take a lot of pressure to tip. But it is quite possible, say if someone sat on the edge.

Consider adding several more support points around the edge (at least 4 more). This would increase the supported area to nearly 3 feet, and reduce the unsupported section to just over 6 inches.

• Oh wow I never saw it this way and thank you for being thorough about this. Actually the edge would just be supporting plates and glasses since it is a dining table. If more rubber support isn't available, up to how many inches can the glass exceed the base? I think our old glass top only had a +3inches from the edge of the base itself. Jan 12, 2016 at 14:45

safe for dining purposes?

Yes.

Of course everything is relative and nothing is completely safe. The glass you describe will injure someone if you beat them with it, and it's not safe to ingest orally.

Make sure the edges are finish sanded free of any sharpness. And make sure the table is strong enough to support the added weight of the glass, plus how ever much weight you for see putting on it, and some margin of safety.

But it sounds plenty strong to dine on. You could probably take it out to 8 or 10 inches just fine as well.

• So the excess 6 inches off the edge of the base table won't just give out...? Jan 12, 2016 at 12:34