I practiced a few times with a drill press while I was visiting David Harwell at Barnstormers Workshop. This worked really well, but I got to thinking - How will I be able to burnish deep into the cowl? The throat of the drill press is only a few inches deep.
So, I tried burnishing by hand. That way I could make the neat little swirls anywhere I wanted. Much as I tried to hold the drill still, the pad wandered. The swirls looked awful. Oh, well. So much for that theory.
Paul Dougherty made a really pretty burnished cowl on the Golden Age Air Museum's Winstead. I always admired the cowl, so I called Paul and he told me how he did it.
Basically, you make a 2 inch hole in a thin piece of plywood. This keeps the pad from wandering.
Then, you just move the hole down the line and burnish with a portable drill. I clamped a wooden guide to keep everything straight (like Paul told me to do). This worked really well.
The Jenny cowl has lots of louvers and beads. Before you can do any of that, the flat cowl must be fully burnished. Using the practice piece, I experimented making the 3/16 in. radius bead using an Eastwood bead roller. It worked very well. The beads were 3/23 in high just like the Curtiss drawings specified.
On a more productive note, the first side cowl was trimmed today.
I couldn't resist hanging up the test piece!
Anyway, the perimeter of the side cowl was cut to match the lower longeron.
Here is what the cut out looks like at the lower wing attach point. More hand filing will be done later.