Door Catch (Weatherstrip clearance)

Note: This model is customizable (parametric), this means you can change its characteristics to fit your needs.

TLDR: A door catch that solves the problem of exterior/balcony doors tugging open due to stiff weatherstripping. It keeps the door gently, mostly closed to preserve indoor temperature.

The problem

Some exterior doors do not have a handle on the outside for security reasons. If there is a rubber weatherstripping or sealing strips that create compression resistance, some door catches don't engaging properly. There are door catches that engage with a locking mechanisms but can only be operated from one side of the door. Also, a locking mechanism easely breaks if someone unintentionally forces the door open (usually kids 😅).

The solution

This model solves the problem with an extended-reach flexible hook that easily snaps over a cylinder pin even when the door cannot close completely. The goal of this catch is not to pull the door tightly shut, but rather to keep the door mostly closed so indoor temperature is preserved. As a bonus, you can fully open the door from both sides and does not break due to someone forcefully opening the door.

Model consists of:
• Frame-mounted cylindrical catch pin (Ø14 mm)
• Door-mounted flexible hook (customizable reach)

Both parts have Ø3 mm holes for wood screws.

For somewhat heavy doors with weatherstripping, 3-6mm offset should be enough to hold the door slightly shut.

Mounting instructions:

1. Close the door
2. Join the model parts in a 90 degree angle.
3. Hold both parts in the corner between the door and the door frame. Preferably close to the top of the door.

4. With a pencil or pen, mark the screw holes for the frame catch pin.

    

    

5. Screw the frame catch pin in place.

    

    

6. Place the hook on the door, mark the screw holes and attach the hook. Make sure to leave at least 2mm space between the hook and the base plate of the pin (red arrow below). If you don't leave that space, the hook might not catch the pin properly.

    

Note: The longer you make the hook (if customized), the more distance you need between the hook and the base plate of the pin. 2mm spacing is enough for a hook with a 6mm offset on a 90cm wide door.

When the door closes, the flexible hook spreads slightly and snaps over the cylinder, holding the door gently but securely in a mostly closed position. Because the hook has a longer reach, it engages reliably even when the door stops early due to rubber seals or change in preassure in the house, pushing the door.
 

The presets

I've created a few preset profiles that should work with most doors. As reference, the “3mm offset - 3mm stiffness” profile works well with a 80x200cm balcony door with tripple glass (about 70kg/154lbs)

How to customize

1. Pull the door as close as possible to the frame without closeing it completely. You will feel slight resistance from the weather strips.
2. Measure the gap distance between the door and the frame (in millimeter)
3. Click on the customize button above and enter that measurement in the “offset field”.

MODEL UPDATE: I realised that having the screw hole width change when altering the model stiffness is not a good prerequisite for testing. Therefore I changed the parametric model so that the screw hole distance has a fixed width when customizing.