How do you avoid double doors from jamming when opening at the same time?

Question

I'm installing double interior doors for the master bedroom. Unlike many double door installations where one of the doors is locked into place with a flush bolt, these doors will each have a ball catch at the top. This will allow each door to be opened individually or both at the same time. I'm not concerned with having these doors lock.

The problem is that when you try to open both doors at the same time, the corner of the edges get slightly closer and the doors can jam into each other. I have considered the following possible solutions but I'm not sure what would be a good balance of practicality and esthetics:

1. Leave the doors as is and get in the habit of opening the doors one at a time
2. Increase the gap between the doors
3. Add a radius to the inside corners

Even though I can see myself getting used to opening one door at a time, anyone unfamiliar with this quirk could make the doors jam into each other. I think that a larger gap will compromise privacy and make it look like an improper installation. I'm concerned a corner radius might make the gap between the doors look larger than it is or just not look right either.

Are there any other options I have not considered? What would you do?

Answer 1

If you have a router, you can add a slope to the edge of the doors:

From the outside, this will look like they are touching, so it would probably look better than a radiused corner.

Answer 2

So make the gap bigger and for privacy install a "soft" seal on one or both edges. That will fill the larger gap without causing locking.

Answer 3

A bifold door would open to one side, along a rail in the top lintel. That fits your need but changes the fundamental way the door works so may not suit.

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Another option may be to work on the hinges, so that the virtual pivot point is moved. Kitchen cabinet hinges often have fanciness the allow their path to be slightly non-circular.

Cabinet hinge with relocated center of motion.

Answer 4

Such doors can not, generally, work with rotary hinges that only provide a rotational degree of freedom to the door panel. Basic kinematic informs us that it's impossible: you'll need to bevel the sides, or have an unsightly gap.

Instead of a simple hinge, a linkage-based hinge allows customizing the trajectory of the door, and it can be a combination of rotation and translation, and furthermore the axis of rotation can change its position along the door's travel. You'd want a design where the initial travel of the door is not just a pure rotation, but primarily a lateral translation to open up the gap. Close to the closed position, a point at the swing end of the door will be following a path that looks like ≺, and only later follow more-or-less an arc.

Unfortunately, such mechanisms often have to be custom made, because the understanding of such things seems to be largely lost among the trades, and thus there's little demand for such products.

If you know any eager mechanical engineers who could help you, it could be a fun project! Or, you could look for a planar mechanisms textbook. It will illustrate (IMHO) satisfying geometric solutions for planar linkage design that you could leverage to solve this problem. It can be a very hands-on project - don't be put off by the "theory" aspect of it. All that's needed is just a design procedure and a bit of understanding of terminology and the linkage types.