Fabricating Aluminum Hinge Parts

In a previous post, Fabricating Steel Hinge Parts, I showed how I made the steel half of one of the Bede BD-4C airplane door hinges. The other half is an aluminum block which gets bolted to the fuselage. For the upper hinge, the block is kind of teardrop shaped and has slot in it for the steel part.

I started by cutting a piece off of a bar aluminum and drilling a .250 inch hole through it. Believe it or not, my bandsaw with a regular wood blade works beautifully for cutting aluminum. I drilled the .250 hole with my drill press and a regular drill bit from the hardware store. Aluminum is so soft that it needs few special tools. (Click any photo to see a larger version.)

Here is a photo of the block along with one of the drawings, to give you an idea of scale.

I needed to drill a hole at the end of the slot and then cut the rest of the metal away with my bandsaw and hand files. I used my optical center punch to mark the location for the hole.

I drilled a .125 hole with my drill press.

Here is the result, with the .250 in hole for the hinge pin and the .125 inch hole for the end of the slot.

I marked the slot and got ready to cut it on my bandsaw.

It only took a couple of passes to rough cut the slot.

I finished shaping the slot with a small metal file. The aluminum is so soft that it only took a few minutes, even with this little tool.

I just kept working gradually at the aluminum, testing fitting a scrap of .125 thick steel into the hinge.

When I was done filing, I had a block that looked like this.

Here are the two pieces of the hinge, with a scrap of rod as a temporary hinge pin.

This last photo shows how the hinge attaches to the door.

I will sand the block down to be teardrop shaped later. For now, it is easier to work with a rectangle.

By the way, I finished up the left door frame today. If you look closely, you can see the steel half of the hinge tack welded in place. Both doors go to the welder tomorrow.