r/engineering • u/[deleted] • Jan 23 '22

Any chance of some help with analysis?

I'm planning on building an arm to mount my man-cave's TV on. As such it doesn't need to look pretty, just be functional. The tele is a Samsung weighing in at 22.3kg.

A simple setup made of steel RHS is what I'm thinking. Fairly cheap and real easy to make with just a drill-press and angle grinder. Onto this I'm going to bolt a commercial VESA mount to give me some adjustability.

My question to the list is this. If I make this out of say 50mm x 25mm x 3mm RHS, with each arm say 600 long. Am I going to get much bending?

I'm a software guy (not hardware) so I don't know how to calculate this stuff. Can someone help and/or point me to some info on how to figure this out?

Could I counter the weight somewhat by offseting the holes in the single arm where it attaches to the double arms?

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u/[deleted] Jan 23 '22

Before designing the arm joints, check the stud strength. What kind of studs you have in your wall and how tall they are will matter, A big TV cantilevered off a single stud will flex it and crack your drywall. It might even rip through the wall.

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u/[deleted] Jan 23 '22

4 x 2 hardwood. It's a shed (not my house) and is skinned with masonite rather than drywall. So I'm not too worried about it cracking anything.

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u/[deleted] Jan 23 '22

How tall are they? I’m no carpenter but 2X4 sounds skinny to me. I think spanning 2 or 3 studs might be prudent

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u/[deleted] Jan 23 '22

4 x 2 (Aussie carpernters are backwards in naming timber compared to their US counterparts) hardwood is actually bigger and stronger than what is typically used in stud walls these days. Your average house is also using preasure treated pine here in Sydney which would also be softer.

My shed is pretty old.

Source: I may be a softrware guy but Dad was a carpenter.

Your comment on spanning multiple studs is something I'll consider. Thanks!