Tue Oct 7 2008

Drilling firewall and armrests

I started drilling the lower flange of the firewall to the forward bottom skin using the black bit shown here. Even though it's a Vermont American bit and is nearly new, it took forever to drill through the .016 thick stainless flange. So I switched to a cobalt bit and the rest of the holes went like a hot knife through butter. The moral of the story: Don't drill stainless using anything but cobalt bits. (I supposed carbide would be even better)

Anyway, here's the bottom flange completely drilled.

Next it was time to straighten the armrests. Here I'm holding my scale along one of them and you can see it is bananna shaped by about 1/4 inch.

After some work with the fluting pliers, they were nice and straight.

Besides clecoing on the F-720R & L arm rests, I also put the F-704K covers in position. I drilled all the holes on the arm rests...

...except for the holes on the forward flange. There is no prepunched hole here, so I need to make sure this flange is square to the sides of the fuselage before drilling. I'll finish that tomorrow.