Straightening twisted doors

[Matty F]

I've made a couple of 3 metre wide doors for my new garage. Because the hinge pins have to be on the outside edge of the doors, the weight of timber on the inside means the doors are twisted somewhat. I expected that, and was going to pull the twist out of the doors when they are shut. When I eventually show you a picture of the doors you will understand! They meet at a right angle.

However it occurs to me that if I put a torsion bar in each door, I can twist them back vertical. I propose making torsion bars out of reinforcing steel. I think it's around 10mm diameter. I'll put a right- angle bend in each end and wind it around until the doors are straight.

Or maybe someone has a better idea. I though of having a counterweight sticking out from each door but that is not very elegant!

[The Natural Philosopher]

If a cuboid twists, then one diagonal is always slightly bigger than another.

To true it up use a tensile member to compress the larger diagonal.

Typically a bit of rod with a thread one end and a tensioning nut and a loaf spreading plate.

Same as a truss rid in a guitar neck.

You can get bending moment as well by constraining the rod into a curve,..as it tries to straighten under tension it bends the wood in the opposite direction.

[Matty F]

One door is 80mm thick and 3000mm wide. I'd have to have a very great tension to pull it straight if the rod is contained within the door. The other door is similar but has a 500mm wide piece sticking out sideways on the end. That of course makes it twist even more. The steel rod I have is 12mm diameter. I'll do some experiments today.

[The Natural Philosopher]

Indeed. But a guitar truss rod exerts TONS so its possible..

Interested to hear them..

[Matty F]

It doesn't matter a lot if the doors are twisted when they are open. When they are shut the twist comes out. One door is twisted 20mm and the other is twisted 80mm. If I could get the twist out it would be a nicer job, and would confuse engineers who look at it, who would expect them to twist. Basically one door is the whole end of the garage and the other door is most of the side of the garage. The doors touch near the corner. There is no corner post. When the doors are open there is a gap of 4 metres. It is not possible to drive a car in the end of the garage, so I drive it through the corner instead.

[Matty F]

I seem to have used up all my reinforcing rod so I can't test it right now. The straight door is good enough as it is. A wire attached to the L shaped door would certainly work if the wire was strung across the corner of the door, which I don't want to do. How about #8 fencing wire tightened with a turnbuckle?

Ascii picture :)

L door O (hinge end) || ||\ || \ || \ || \ || \ || \ Straight door ||________ ___________________________ ||________||___________________________O

[NT]

I'd look at ways to mostly remove the twisting force so the problem si small to begin with. 2 that spring to mind are

1. castor wheel on door bottom if the floor's suitable
2. Swinging arm above the door, with nylon line and weihgt as a counterbalance. This one isnt as pretty but works well enough - do use nylon for its low friction. Aka fishing line.

NT

[NT]

Theres also the option to put a shallow wedge on teh floor with polythene or nylon surface for low friction. This lifts the L door into position as it closes.

NT

[Matty F]

The door opens over sloping rough ground. I think I will remove the L from the left hand door and extend the right hand door to 3.5 metres. It swings quite well at the moment even though it weighs araound 100 kg. One day I will show a pic of my wooden hinges!

[NT]

Just another wild though: if you hinged the corner, when closing the L door you could have the left hand part slot home into some sort of restraint and then close the front part of the L door, ensuring relatively good alignment.

What is it, concrete? 6x6 framing?

yes do :)

NT

[Matty F]

I have now removed the L from the left hand door and rebuilt the right hand door to 3.5 metres wide. They both hang fairly straight. The top of each door will latch on to the roof and the door lock will pull the two doors together.

It's 75x50mm framing with 12 mm plywood. 3.6 metres by 1.8 metres. I can lift one end OK.