Middle hinge

[snozzel]

when hanging a door with three hinges on where should the middle hinge sit....exactly 1/2 way up?

 

[big-all]

yes central between the hinges unless its a realy heavy door then around 10" below the top hinge to give it more support

 

[^woody^]

I've often wondered about the siting of the "middle" hinge in commercial buildings with heavier doors - as no-one has ever given me a definitive answer as to why it is not in the middle as opposed to 3/4 the way up the door.

It seems to be a modern idea, but I am sceptical as to whether it is better there, rather than actually in the middle

 

[gregers]

its funny when i used to work on site,one job they insisted the so called middle hinge was positioned about 6 inches down from the top hinge,and the doors wernt partically that heavy.

i allways set the butts at 6" and 9" then divide whats left.

 

[EddieM]

it's to do with the angular momentum applied to a door, when someone bangs into it. The majority of the force will be applied to the top third of the door.

 

[^woody^]

it's to do with the angular momentum applied to a door, when someone bangs into it. The majority of the force will be applied to the top third of the door.

You may be correct but I don't buy into it.

Of all the big heavy doors I have seen in older commercial buildings, hospitals or even in multi-storey residential blocks, I don't ever recall seeing problems with the doors where a central hinge was fitted, and where the door must have got (and still be getting) a lot of use.

And wouldn't loads be shared on hinges, based on travel through the stiles and cross rails?

 

[gregers]

i do believe that most of the weight is on the top hinge,hence when the pins or washers wear out its nearly allways the top hinge to suffer.

 

[mattylad]

Unless that door is being booted by someone trying to kick it down

 

[^woody^]

The weight of the door, should theoretically be shared on the two or three hinges equally

If one hinge is slightly higher, or misaligned, causing the washer to compress more, then that will wear out quicker, and presumably as it is impossible to fit hinges exact, then one will always wear more. I'm not sure it will always be the top one though.

Consider rising butts, or gate hook and bands - its possible for all the load to be one one hinge ... and that could be the bottom one, and you could push and pull that all day without the top hinge coming off

 

[noseall]

A middle hinge (central to the t&b hinge) can also prevent warping. Ho hum.

 

[jono_h]

it's to do with the angular momentum applied to a door, when someone bangs into it. The majority of the force will be applied to the top third of the door.

I can kind of see this, but in a different way. The unhinged side of the door is being pulled downwards by gravity and will pivot around the bottom hinge, putting more force on the top hinge. You can see if this if you remove the top hinge but not the bottom, the top of the door tips - if you remove just the bottom hinge the door will stay in place.

A third hinge, nearer the top, spreads this turning moment (although the actual weight of the door is split equally between the hinges)

Could be a load of rubbish of course.......!

 

[^woody^]

... if you remove just the bottom hinge the door will stay in place.

No, the door pivots on the remaining hinge just the same.

Gravity is actually pushing the door down vertically. Operating the door applies a turning moment to the hinges, but (failing any actual scientific proof) the force will be the same on each hinge.

I can't see how one particular hinge will receive more load unless there is a specific force pulling close to a hinge. But in practice, this wont happen

 

[mattylad]

It looks better if it's evenly placed in between the others

 

[big-all]

No, the door pivots on the remaining hinge just the same.

Gravity is actually pushing the door down vertically. Operating the door applies a turning moment to the hinges, but (failing any actual scientific proof) the force will be the same on each hinge.

I can't see how one particular hinge will receive more load unless there is a specific force pulling close to a hinge. But in practice, this wont happen

not strictly true
it would be if the centre off gravity was on the hinge line but its around centre off the door
so the top hinge has sheer force towards the floor and pulling force pulling directly away from the hinge

the centre hinge has as much sheer force but fairly neutral pull/push

on the bottom hinge you have sheer force and the door pushing the hinge onto the frame

 

[^woody^]

It looks better if it's evenly placed in between the others

Agreed.

Thread closed LOL