I am planning to hang a projector which weighs 8lbs (~3.5kg), on a wall arm.
The arm weighs 4lbs (~1.8kg) and has a load capacity of 44lbs (~19.9kg), and I'll be hanging the projector at the arm's minimum extension (~12").
The fact that the arm is extended away from the wall adds leverage and therefore increases the effective force applied by the weight of the projector so as far as the wall is concerned, it's not just the 8lbs. I'm not savvy enough to calculate this though- perhaps someone can point me in the right direction?
I have (to be confirmed) found a 2" stud with a stud detector in what appears to be 1/2" or 5/8" drywall/plasterboard. I have some molly bolts, various size screws with rawl plugs available.
I am wondering
- If I put 2 screws into the stud and 2 molly bolts in the plasterboard would it likely hold?
- If it's not a stud, and I use 4 molly bolts, would it likely hold?
Commonly people suggest placing a board behind the arm it seems, but I'm hastened to do this as effectively the questions above still apply.
There's equal leverage, but it increases probability that I would hit 1 or more studs, or enable me to spread the molly bolts around a greater area.
Best Answer
The answer to "how do I mount an articulating arm to drywall" is "you don't". Find a stud. It's not worth taking the chance considering the cost of the projector.
Your best bet is to get this hung off of the stud. To do this effectively, you should firmly attach a piece of plywood or hardwood to the stud, and then attach the arm to the wood. I suggest pre-drilled lag bolts for attaching the plywood to the stud, and T-nuts with bolts and lock washers to attached the arm to the wood.
If you can't find a stud where you need one, then find them on either side, cut a piece of wood to span them, and bolt the arm to that piece of wood.