Sandstone Sign - Secure fixing indea needed?

[robjmcnulty]

Hi, I am making a sandstone sign and it has a sandstone engraved pannel in it, this pannel is 860mm by 440mm and its 50mm thick. I needed a strong bracket to attach it to the frame from the back. Any ideas would be great. Thanks. Rob

 

[CH5OH]

glue it (epoxy)

 

[MadMango]

I agree, use a two-part epoxy and attach a metal plate to the back for mounting. Maybe something like

http://www.masterbond.com/tds/ep21tdcht.html

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[ivymike]

that's along the lines of what I was thinking too, but I thought that perhaps the backing plate should have a few 20mm diameter pegs to interface w/epoxy-filled holes in the back of the sandstone. My thought was that the back layer of the sandstone might just shear off, and at least the pegs could help carry the load deeper into the "rock."

 

[MadMango]

A metal angle at the bottom to support the weight of the sign could also work, if your overall design will allow it. I would be worried about creating "pockets" of any significant depth, especially if the engraving has already been completed.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[drawoh]

robjmcnulty,

Can you build a frame around it? If the frame wraps around all the edges, you do not have to worry about adhesive.

JHG

 

[zdas04]

Shear in sandstone happens at a really low force. Where I live (New Mexico) sandstone signs are common. The ones where people just hot glue the support on the back generally last until the tourist puts it on a wall plus a few weeks.

The best ones I've seen have had a groove milled horizontally in the back (staying at least on thickness away from each side) and a piece of angle iron (with the necessary hardware welded, soldered, or glued to the angle) epoxyed into the groove. The groove should be between 1/2 way up from bottom and 2/3 up from the bottom and I'd make it to accommodate 25 mm angle (don't worry about it breaking, the epoxy is a lot stronger than the rock).

This chunk of friable material weighs over 40 kg so you need to think "industrial" instead of "consumer".

Just out of curiosity, will the sign hang on the wall or sit on the ground? Even if it sits on the ground, the above will give you a way to secure it from walking off.

David

 

[MintJulep]

I was going to suggest exactly what zdas04 described.

 

[ornerynorsk]

Is it going to be hanging in such a way that the failure of the mounting system has a potential to kill or injure someone?

 

[Ron]

Sandstone is subject to movement from wetting/drying. Zdas04 is correct, but you also need to consider doweling.

We have doweled numerous stone panels and I have investigated failures of same. Dowels installed at 45 degree angle (downward from panel to substrate) work well.

Shelf angle works as well, but you have a corrosion issue to deal with if in an area where water intrusion is an issue.