Sun Aug 15 2021

Gap strip shims and other stuff

I started making up some shims to go between the right side curved flange and the strip when it occurred to me that it might be useful to explain how to make nice cuts in aluminum (or other metals) with snips. Have you ever laid out some cut lines, carefully followed them while cutting with snips, only to find that the edge is all distorted when you're done? Even when using bypass snips as shown here? Well, it's because you're doing it wrong. :-o Seriously. I used to do this wrong all the time until I observed another builder, my friend, Tom, doing it the right way. So, for the benefit of others, here is the right way to cut with snips. After laying out your cut line, make an initial cut about 1/8" to 3/16" away from that line as I'm doing here. Make sure that the blade which is supporting the piece you want to keep is laying flat against the material you want to keep.

Next, trim away half to two thirds of the excess. As before, make sure the blade on the side of the "keep" material is flat against the surface of the material.

Lastly, cut on the line, of course keeping the blade on the "keep" side of the line flat against the material. Note the neat, undistorted edge.

If you've done it right, the scrap material will curl into a spiral. This approach takes more time, but yields superior results as compared with making the first (and last) cut on your line.

With shims fabricated, drilled, and positioned between the strip and the curved flange, the strip spacing from the canopy skin appeared to be spot on.

Getting close to cutting out and fitting a skin over this structure. In preparation for that, I needed to get the .025 strips fitted between the rib flange and the doubler flange. Jo made these strips for me a week or so ago. I didn't know exactly how long to have him make them, so they're extra long. I put them in place and marked the length, then cut them down to length, filed the edges, and rounded the corners.

I located the centerline of the rib flanges and drew that centerline out onto the firewall flanges as well as the canopy skin. So, when I lay my new skin atop this structure, I will have some lines available to transfer onto the skin prior to drilling through the skin and structure.

Here are the shortened spacer strips with some double sided tape. As shown before, these will be sandwiched between the rib flanges and the doubler flanges, but I don't want them moving around when match drilling through the skin.

The tape also made it possible to stick the strip in place and check to ensure it wasn't overlapping the flange bend before putting the doubler in place.