90° sturdy shelf bracket

[geojay]

I need to securely fix a substantial shelf to a wall and it's important that the shelf is horizontal. I purchased some sturdy brackets from a local hardware shop, I suspect they were the same that Screwfix sell at https://www.screwfix.com/p/hi-load-mitred-shelf-brackets-white-300-x-300mm-10-pack/135vj . Once the shelf was up, I checked it was horizontal with a spirit level and it was not, the wall was perfectly vertical though. Confused, I checked the brackets with a set square and sure enough, they were not square! The one star review on that Screwfix page suggests they're about 93° which sounds about right. All of the brackets were the same and I assume it's by design.

Can anyone explain why these brackets are made this way and, more importantly, suggest where I can find some similar looking brackets that are square? The London style aren't sturdy enough and I'd prefer not to use spur shelving as I don't need the shelf to be adjustable in height and I think it looks a bit clumsy otherwise. It seems that everywhere sells the same three options for shelving brackets! The horizontal needs to be around 300mm.

Thanks in anticipation!

 

[freddiemercurystwin]

The additional 3° just allows them to be loaded though doesn't it? Then after they're loaded down they'll be down nearer 90°.

 

[geojay]

I did think of that but this design is so substantial, I can't imagine they'll ever move that much...

 

[freddiemercurystwin]

They have a capacity of 50kg, it seems pretty reasonable to think they'd deflect by 3° with that kind of load hanging on them.

 

[bernardgreen]

Maybe the intention was that the shelves should have a slight slope towards the wall to reduce the risk of any round objects rolling off the shelf.

Could you put a spacer between shelf and bracket ?

 

[foxhole]

They may also sink a fraction of mm into wall plaster when screwed in hard, the extra compensates for this.