Getting Ready For Bending

It was an unusually cool day for August in Texas, so I spent all day on the plane. Once the last side of the last FAP panel is completed (Monday?) we will be ready to use the Hinged Panel Tool to fold the sides up on the fuselage. Before that could happen I needed to correct a mistake. We had accidentally applied epoxy, but not cloth, to an area that needs to bend, and I needed to remove that layer. Even without cloth there was no way that area of the panel was going to flex like it needed to. Ordinarily that would been sand paper and a lot of elbow grease, but I have The Machine, the 4'x8' CNC router table I built. I built it because I was originally planning on building a metal airplane and wanted to make my own 'kit' rather then using tin snips. The Machine is what I have been using to cut out my foam panels accurately.

 After aligning the panel on The Machine's bed and measuring the X and Y coordinates of the area I needed skinned, a software package I use with The Machine was only too happy to create a tool path for the router to follow. I chucked in a 3/4" mortising bit and, with my hand hovering over the emergency stop button, let The Machine skin off  the 1/25 of an inch thick layer of epoxy. It worked out perfectly.

 
I next let The Machine trim and straighten all of the sides of the 3 finished panels. Basically I had it make multiple passes along each side, each maybe 1/100" deeper than the last pass until I was happy with the resulting edge. Four passes was usually enough. Here is a before/after pair of pictures. The Machine only needed to remove 0.040" to get that edge clean and dead nuts straight.

Lastly, I mixed up some micro (epoxy and glass balloons mixed into a putty) and joined the 3 finished panels together on the HPT. The screws and fender washers are to keep the seams tight as the micro cures.

Time Spent Today: 8.0 hr