brackets
I saw these on eBay. What is their intended use? I was able to find lots of photos of similar items on Google but not of their actual use case.
They seem to be for use against a flush surface. When would this bracket me useful compared to using screws alone?
There are no standard sizes.
Braces of the type you are considering most commonly have holes that are less than 1/4" and more than 1/8", somewhere around 3/16". They are usually intended for #6, #8 or #10 screws. You could probably use 1/8" bolts, or maybe 3/16" depending on the brace. 1/4" bolts probably won't fit unless you ream out the holes.
Which bolts will be sufficient depends on how much strain will be on them and how many braces you are using.
A medium duty, standard single slot, blade bracket?
Source: beta.lvmannequins.com
Another option might be removing the plastic caps off the uprights and slide something down there; put 'legs' on the board and slip it in. Isn't that how some partitions with glass tops work?
Best Answer
They can be installed in various ways. You can install them to join corners straight from one surface to the other, or diagonally from one surface to the other. You can also use them in a situation where you want to allow the expansion/contraction or slight movement of a fixture. This would allow say a table top to expand or contract with temperature or humidity changes. This would then keep the table top from cracking.