I'm looking to install some floating shelves (I originally wrote "cabinets", sorry) in my apartment and want to put some moderately heavy things on them (likely under 100 pounds over a 48 inch long span).
I'm 95% sure there are metal studs and I can reasonably identify their location (though not necessarily their center) via my magnetic stud finder.
My only real question is how would I know which length toggle bolt to purchase?
I know I'd need 1/4 inch width bolts but I'm uncertain on the optimal length (presumably 3 or 4 inch)
Also, if the shelving bracket has 3 holes
should I use three toggle bolts per bracket or is that overkill (or perhaps would just weaken the drywall/stud?)?
Best Answer
One does not use toggle bolts in studs. They're for hollow-wall applications and would require you to drill very large hole through the stud flange, which isn't a great idea.
It's also fairly difficult to drill the cabinet for toggle bolts, transfer the locations to the wall, drill larger holes for the togglers, insert the togglers in the cabinet, then get all the togglers into their respective holes in the wall. It's a real hullabaloo and a thing to be avoided.
Use three or four screws with sheet-metal (fine) threads in each of the available studs and you'll be fine. Since most of the pull-out force is at the top of the cabinet, you might use two screws near the top.
To answer your actual question, though, toggle bolts should usually be just long enough that, when the wings are folded back and the bolt is inserted, they can open up behind the wallboard. Whether they can be longer depends on clearance, of course.