Tue Sep 01 2020

Routing of trim cable in cabin area

This morning, I checked to see if the trim cable could be routed below the fuel pump mounting plate. Unfortunately, the mounting plate won't sit down far enough with this cable below the plate.

...so, it's going to have to go on top of the plate, between the fuel pump and filter. At the forward edge, the cable goes down over the edge, creating a bad chafe point.

I marked out the location on the front edge where the cable will pass, and removed some nutplates in preparation for forming the edge here.

I cut a forming block to fit closely between teh flanges and sketched out a spout shape.

Some filing with a rasp had the forming block appropriately contoured.

I made a clamping plate to go on top. It has a large hole to reach down through with a forming tool in the rivet gun.

I made a round-nosed Delrin block with a hole to receive a short rivet set.

I was now ready to try forming the mounting plate. However, seeing how thick that plate is (.063) led me to try forming first on a spare piece of material

Here's a view from the front (under the top clamping block) showing how well the plate formed. I.e. it didn't. I think the Delrin is just absorbing too much of the impact.

So I located a rivet set I could modify. Not sure where this one came from, but I'll never be driving rivets this large. It's fair game to modify.

Some time with the grinder and scotchbrite wheel had it nicely smoothed over.

Well, that tool definitely formed the sheet. Unfortunately, the sheet cracked in the process. I'm very glad I tried this on a spare piece of material.

Maybe the problem is that the -T3 temper makes the material just too hard (i.e. not enough elongation before fracture). There's a trick that you can remove the temper of aluminum if you mark on it with a Sharpie, and heat it up. When the sharpei marks disappear, you're at the right temperature.

Sharpie marks fading out...

OK, just need to let this cool down.

Clamped back up and ready to form again. I switched back to the Delrin forming tool.

Well, that's better. I guess. Stilll nowhere near enough.

Switching back to the steel tool.

Better than the first time, but still cracked.

This isn't working. Maybe I'll try a different approach: form the lip in a small piece of material which I'll rivet to the forward edge of the fuel pump and filter mounting plate. I used the sharpie/torch method to remove the temper from this piece.

I left the aluminum hang over the edge of my forming block, maybe 1/2" or 3/4". To put the main portion of the bend, I held a steel rod (socket speed handle) against the edge and whacked it with a mallet.

Ok...this looks like something I can work with.

Did some trimming and sanding to smooth it out.

Hrm...it's too wide to fit between these two fuel lines.

Trimmed the edges down.

OK, that looks pretty good. I'd like to move this aft a bit, but will need to notch out the front edge of the mounting plate a bit. I think that'll be OK since this lip will serve as a doubler.