The load bearing capacity of glass - to bear its own weight

This is the main board for discussing general techniques, tools, and processes for fusing, slumping, and related kiln-forming activities.

Moderators: Brad Walker, Tony Smith

Post Reply
Glass Isle
Posts: 4
Joined: Mon May 22, 2017 1:09 pm

The load bearing capacity of glass - to bear its own weight

Post by Glass Isle »

Hello,

I wonder if anyone could give me some advice.

I am looking for information about the load bearing capacity of glass - to bear its own weight.

I am working on a number of flat fused glass pieces. Each piece will be suspended from the ceiling from a single drilled hole - near the top, think of a pendulum or a mobile.

The pieces will be no bigger than 300mm x 300mm x 8mm (most will be much smaller and 6mm thick)

As the pieces will be suspended from a single drilled hole in the glass, I want to ensure that the glass can bear its own weight.

Does anyone know of any guidance or calculation to determine the capacity of glass to bear its own weight.

If anyone could point me in the right direction for information/advice I would be very grateful.

Many thanks
jim simmons
Posts: 478
Joined: Sun Mar 09, 2003 10:37 pm
Location: Hillsboro Oregon
Contact:

Re: The load bearing capacity of glass - to bear its own weight

Post by jim simmons »

All I can think of right now is that a lot will depend on the area of the support piece that is in contact with the lower side of the glass.
If it is very small, it will not hold as much as if it is larger.
I know that isn't much help./
You might do a search on the "shear pressure" of glass.
Or words to that affect.
The other Jim
Brad Walker
Site Admin
Posts: 1489
Joined: Fri Mar 07, 2003 9:33 pm
Location: North Carolina, USA
Contact:

Re: The load bearing capacity of glass - to bear its own weight

Post by Brad Walker »

There's a great deal of data on the load bearing capacity of glass shelves (even some online calculators), but they all require two support points, not one. What you're talking about is drilling a hole in the glass and suspending it from the ceiling, which adds such complexities as the size of the hole, type of screw or whatever, and the material you're screwing into. The size glass you're dealing with isn't very heavy (around four pounds/two kilos or so), I would think it would be pretty easy to do a few tests to find out how much weight would cause your particular setup to fail.
DonMcClennen
Posts: 381
Joined: Sun Mar 09, 2003 9:09 pm
Location: Ontario

Re: The load bearing capacity of glass - to bear its own weight

Post by DonMcClennen »

I suggest you drill the holes big enough to allow a metal eyelet be inserted. These can be secured with a proper adhesive. This allows movement of the hanging cables to happen without causing abrasive stress on the raw glass at the hole.. Thicker (1/4") glass will accept 2 eyelets (one from each side). I've used this method successfully many times over many years. In from edge of glass at least 3/4" .
"The Glassman"
Glass Isle
Posts: 4
Joined: Mon May 22, 2017 1:09 pm

Re: The load bearing capacity of glass - to bear its own weight

Post by Glass Isle »

Many thanks to you all @ Don, Brad and Jim. I appreciate you taking the time to consider the issue and put forward some suggestions.

Jim, I will search for "shear pressure". Don and Brad, I will also test your suggestions. I came across the following information online which isn't too dissimilar to your suggestion Don, although this was in relation to toughened glass not annealed fused glass:

1. The minimum diameter of a hole must be 5mm for glass thickness up to and including 5mm and for thicker glasses, at least the thickness of the glass being drilled.
2. The distance between the glass edge and the hole should be at least twice the glass thickness.

Thanks again

Glass Isle
Kevin Midgley
Posts: 773
Joined: Mon Mar 10, 2003 11:36 am
Location: Tofino, British Columbia, Canada

Re: The load bearing capacity of glass - to bear its own weight

Post by Kevin Midgley »

Glass Isle
Posts: 4
Joined: Mon May 22, 2017 1:09 pm

Re: The load bearing capacity of glass - to bear its own weight

Post by Glass Isle »

Thank you Kevin that's great. He uses a method of hanging I haven't seen before.

Glass Isle
Kevin Midgley
Posts: 773
Joined: Mon Mar 10, 2003 11:36 am
Location: Tofino, British Columbia, Canada

Re: The load bearing capacity of glass - to bear its own weight

Post by Kevin Midgley »

Best of all you won't figure out how exactly it is done by looking at the photos. :lol:
Glass Isle
Posts: 4
Joined: Mon May 22, 2017 1:09 pm

Re: The load bearing capacity of glass - to bear its own weight

Post by Glass Isle »

Kevin, I think it is similar to fixtures and fittings supplied by this company in the UK http://www.shopkit.com/case-studies/cla ... ss-design/

But these works both use two points of support and do not bear their own weight.
Kevin Midgley
Posts: 773
Joined: Mon Mar 10, 2003 11:36 am
Location: Tofino, British Columbia, Canada

Re: The load bearing capacity of glass - to bear its own weight

Post by Kevin Midgley »

yes that link definitely has the concept except that the ones I've seen are no way as visible as part of the art. Essentially invisible. That is why they remain a mystery.
Bert Weiss
Posts: 2339
Joined: Tue Mar 11, 2003 12:06 am
Location: Chatham NH
Contact:

Re: The load bearing capacity of glass - to bear its own weight

Post by Bert Weiss »

Bert

Bert Weiss Art Glass*
http://www.customartglass.com
Furniture Lighting Sculpture Tableware
Architectural Commissions
Post Reply