Tue Nov 03 2020

Canopy forward skin

Here's why the bend wasn't positioned correctly. Even though I had the bend tool located correctly, it appears the skin or the bend tool flexed and the bend was formed about 1/8" too far outboard. Well, it was a high risk operation...likely to go wrong on the first attempt. Only thing to do now is to start over.

I decided I'm going to need to use a different approach for the bend...essentially like a press brake. To do that, I laminated up some hardwood to use for creating the bending tools. Here's one of them clamped up while the glue dries.

While the glue was drying on those blocks, I got out some more sheet metal and traced the outline of Van's skin.

...and cut it out.

After some tablesaw work, I had the forming tools completed. I'm using a 3/16" rod for the nose of the upper tool, which should yield a 3/32" bend radius...not a perfect match for the 1/8" bend radius of the triangular gusset arms, but as long as it's equal or smaller, it'll be fine.

With a test piece of aluminum positioned, I used my arbor press to make a bend. Since the bend needs to have a greater angle at the aft end than at the forward end, I'm intentionally pressing towards one end of the tool.

First attempt. The bend angle here is greater than 12.5 degrees, but didn't seem sufficient. So, I clamped it back up and bent it some more.

I also moved the tool down in the press somewhat so that it was about 4.5" along the length of this 12" long test part. This time, I increased the bend angle to about 45 degrees (at the aft / most bent end).

Okay, 45 degrees was slightly too much. I just opened it back up slightly by hand. This is looking pretty good. Notice how it lays pretty well along the flat side of the triangular gusset arm.

Another view showing more of the side. Notice how the bend transitions from, maybe, 40-ish degrees at the aft end (left side of this photo) to essentially no bend at the forward end.

Here's a view from the front. Essentially no bend. This looks pretty good. Tomorrow I'll make another test part, then work on getting the bend incorporated into the canopy frame skin.