Short session tonight, mostly cause I’m tired. I pulled all the angle/reinforcement pieces back off the firewall again, deburring the rivet holes as I went. Nest up was deburring the rivet holes in the firewall itself. Most of these – that is, the prepunched holes I match drilled – were pretty straightforward, but the 1/4” holes I drilled for the rudder mounts were truly ugly. I’m not even sure you can call what I had on those holes a burr, it was more like a lip. So instead of just hitting those with the deburring tool, I manually sanded them down the the Dremel and flap wheel, ran the 1/4” bit through them again to ensure they were still sized OK, and finished the the deburring bit.
The last order of business was to put a required bend in the firewall. The upper portion is bent eight degrees forward, I believe to facilitate a better fit with the cowling. The instructions are pretty useful here, providing a good method. I used my digital level to gauge the bend, which was really easy. Compared to the aluminum sheet I’m used to bending, the stainless is pretty soft and doesn’t have a lot of springback. It was pretty easy to get an acceptable bend:
Next up is a whole bunch of dimpling and countersinking. Seems like this firewall assembly should be together in no time!