Cary wrote:My previous hangar at 3V5 before it was closed had a bi-fold. Although it worked fairly well, a cable came undone once and nearly cost me my airplane. If I were to build my own hangar, I'd probably opt for an overhead bifold, but I'd sure want a door that was reliable and had some sort of safety mechanism to keep it from dropping if something broke. I think that would eliminate any home-made door.Cary
Here are my safetys for a bifold/hi fold style. Homemade and Handy and safer than most.
In this photo notice there are four independent supporting cables that lift the door. If one breaks the others will keep it from falling. Many older doors rely on just one or maybe two cables that thread through pulleys to multiple pull points. If one broke the whole door came down, or with two cables one end dropped, twisting the door.
Four independent cables provide saftey and notice they are anchored at the top of the door frame itself making the tension of pull transfer only to the door frame, and not to the building header. The hinges of the door then spread only the lift weight to the header, not to cable pull points attached to the header. The cable anchor points at the top of the frame then also move outward as it opens eliminating the back and inward pull of cables that comes with anchoring to the header. Also notice the cables at the hinge point, they go over kickouts. As the cables tighten it kicks the hinge point outward starting the fold. This door cannot fall if one cable or hinge breaks. The motor and limit switch box along side allows setting the upper stop point and the lower stop point for automatic operation. I wired mine so on one push it fully opens but wired the close button so I have to stand there and hold the button the whole time. I can't make that last second dash to move something in the way while the door continues to close. I made this nearly idiot proof with the change below.
Second photo shows the safety lock/unlock I made. The over center lock lever handle has a plate welded to it. The plate covers the open button when in the down/locked position preventing anyone from pressing the open button when the levers are locked. You have to lift and unlock the lever first. Easy solution and preferable to the fate of hitting the opener button when the door is still locked down. Many bifolds have met their early demise by this screwup.