Making a swing Joint Load Bearing, Engineering Question

T

thebiz

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I'm making a swing joint to attach to a bed so i can store it upright and lower it when needed.

Here is a diagram of one piece.

[broken link removed]

A: Is a piece of metal that the load of the bed will be bearing down on from directions 2 + 3 when the bed is lying flat.

B: Is a piece of metal that is screwed rigid to the wall.

C: Is a Bolt joining both bits of metal.

A and B have a nylon washer between them and are tightened with a Nyloc nut.

Piece A will be loose enough to swing in direction 1 This will give the bed the ability to pivot.

There is one of these joint each side at the head of the bed.

My questions.
I'm trying to work out if the joint will be strong enough to hold the bed.
It's light weight pine but I'm not sure how much load will be generated when it swings.

I'm not looking for may maths, just opinions on how thick I should make A+B
and How thick a bolt should C be.

Thanks
 
Hi there
My dad is a sheet metal worker/welder - I've printed diagram and details so will hopefully get some kind of feedback from him this evening - will post back later.
 
Interesting question, I'm no engineer but from looking at simmilar hinges and pivots etc I reckon 3 to 4mm should be plenty stiff for the plates. I'm sure it's easy enough to find out the shear strength of standard bolts online but I reckon an M10 or 12 should be more than adequate, but wouldn't a bushing be a good idea also? Or at the very least a clear shank bolt with only the end threaded? Rather than try and fabricate something from scratch why not go to an engineering factors or similar and see what type of standard components are already available? Hafele do specialsit hinges and pivots etc too....
 
Lorrie - Thanks appreciate it.

Carpenter - Good points.
I like the bushing & clear chank ideas

As for going to an Engineering factors, I never considered that they were open to the public, I'll look up a few.

Thanks
 
hi Biz
my dad threw a few figures at me but said he wouldn't like to quote sizes/measurements as he couldn't be 100% sure and wouldn't guarantee he was right..
So he was quite vague... sorry hope ya got it sorted
 
 
Why not test the device by hanging a test weihht from the hinge.the test load to be 3x the bed weight.if the hinge holds overnight it should be ok for your bed
 
Lorrie said:
hi Biz
my dad threw a few figures at me but said he wouldn't like to quote sizes/measurements as he couldn't be 100% sure and wouldn't guarantee he was right..
So he was quite vague... sorry hope ya got it sorted
Click to expand...

No Prob thanks anyway
 
allo said:
Why not test the device by hanging a test weihht from the hinge.the test load to be 3x the bed weight.if the hinge holds overnight it should be ok for your bed
Click to expand...

I'm quite sure it would stand up over night, it's wear and tear over 6 months of use that would be my main concern...

I think i'll just build a heavy duty one and apply the good old guestimation factors.

Thanks for all the replies
 
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