Vandal Proof Nuts & Bolts For Memorial Bench?

[Foresty Forest]

We met a friend on our dog walk and she showed us how local kids had unbolted a couple of slats from the bench she'd erected in memory of her husband. They'd thrown them into the silt of the river where they can't be retrieved. The slats were simply bolted in place and they must have brought a spanner to undo the nuts. There's plenty more slats for the kids to easily have a go at. Is there anything we could replace the nuts with that would be difficult to undo? The slats are wood and would eventually need to be replaced. At a guess the bolts are probably 10mm diameter.

Thanks

 

[Old Salt]

What about recessing the nuts and bolts and then glueing in a wooden plug to fill the recess.

Or a 12 bore shotgun to get rid of the vermin.

 

[bernardgreen]

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The hexagonal part of the nut breaks off when the nut is fully tightened, The nut can then not be undone as there is nothing for the spanner to grip.

 

[Foresty Forest]

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The hexagonal part of the nut breaks off when the nut is fully tightened, The nut can then not be undone as there is nothing for the spanner to grip.

These sound good. But what happens when you need to replace the slats? I guess remove the wood around the bolts and cut with a hacksaw?

 

[freddiemercurystwin]

There are plenty of types available, just google tamper proof nuts, but you will have to purchase (and keep safe) the special keyed socket to do it up and undo it eg https://www.tcfixings.co.uk/product/m10-kinmar-removablesecurity-nut-zinc-cr-3/13579