Bede BD-4C Door Hinges Completed

Believe it or not, sometimes life gets so busy that a guy cannot even work on his airplane. When that happens, the best answer is to take a few days of vacation and get stuff done. Yesterday, I finished up the hinges for the doors on my Bede BD-4C airplane. In my last post, I showed you how I fabricated the hinges out of aluminum bar stock. Here is a sneak peak at the completely finished pieces. The rest of this post documents the path I took to create them.

After fabricating the rough hinges out of bar stock, the next task was to drill holes in the hinges so that they could be mounted on the fuselage. I was starting with pieces that looked like this so I had to drill holes which matched up with the holes that already existed in the fuselage.

If you look back at the first photo, you will see that every piece has two mounting holes. The two holes in each of the bottom hinges were easy; I could clamp the hinges in place and back drill from inside the fuselage. The top hinge piece was trickier; one of the holes could be back drilled but the second could not.

For the top hinge, I back drilled the rear hole. Here is the top hinge for the right-side door, held on with one bolt.

With the hinge unbolted, you can see the two holes behind it. The front hole is blind; you cannot get to the back side of it.

I used a scrap of aluminum to make a template for marking the position of the front hole on the hinge. I drilled a hole in the template and bolted it to the front (blind) hole.

I drilled through the back hole in the fuselage, making a second hole in the template.

Now I had two holes in the template which exactly matched the holes in the fuselage. I traced the outline of the template onto the fuselage with a marker. I removed the bolt holding the template in place and then ran a bolt through the hole in the hinge, the rear hole in the template, and the rear hole in the fuselage. I used the lines that I traced onto the fuselage to get the template exactly in its original position. Then I traced the outline of the hinge onto the template. Here is the result; you can see the hinge outline in green marker.

With the template and hinge removed from the fuselage, you can better see what I had done so far.

I bolted the template to the hinge and that finally gave me a circle with which to mark the location of the front hole on the hinge, itself.

Here is the hinge. The location of the front hole is marked in red, ready to be drilled.

With the location of the hole marked, a quick trip to my drill press produced a piece which fit perfectly.

Here is a photo of the bottom hinge.

I repeated the process for the hinges for the left door. The remaining task was to make the hinges sleek and aerodynamic. You wouldn’t want a half inch thick block of metal sticking out in the slipstream and slowing you down, would you? 😛 Here is a photo of the hinges, 25% done.

Finishing the hinges was pretty simple: cut off some of the metal with a band saw, sand to finished shape on my disk sander, smooth out with the ScotchBrite wheel on my bench grinder, and countersink the screw holes. The finished hinges almost pretty enough to be avant-garde jewelry.

What do you think, would you (or your beloved) wear these?