Lost Screw Holes, and Mill Bastard Files-War Bird Update December

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More “tools of the trade”. Ball-peen hammer, leather hammer, tin snips, and mill-bastard file.

Did not get to spend much time working on the L2-M aircraft in Rutland this summer. Haying weather took up most of the flying time. Farm stand, quirky Angus, sawing lumber, and kids’ camps seem to fill the rest of the days. Now as winter slowly cranks up here in Cabot, I have attempted to start the bi-weekly schedule of trips to S.D. Airservice where  the parts of the Taylorcraft have made a home now for many years. So, at the end of last week I got reacquainted with the project.

The vexing speed of the rebuild: Some days you can spend hours trying to achieve an end, only to have to start over.

I am building the sliding windows on either side of the cabin of the L2-M, one in the door, and one on the left side. The windows are plexiglass that slide in wooden channels, and have aluminum strips on the fore and aft ends that act as handles. These aluminum strips are riveted onto the plexi which has a tendency to want to crack, so you must drill an over size hole in the plexi, insert a spacer (bushing) that fits this hole, then the rivet that goes through the strip, and through the center of the spacer. When you squeeze the rivet it can expand into the spacer, and pull the strips together, without cracking the plexi. Follow me?

The problem is where do you find these spacers? All I have is an old WWII part number that I haven’t been able to cross reference, so I have to make them. They are SMALL! I found some aluminum brake-line tubing, shave off a minute piece, sand it, squeeze it on to a scrap bit of plexi. Result? Rejected! Scott made some comment about how the repair was done by a farmer or something. The aluminum was dimpled and one of the rivets pulled free. The brake-line bushings were too soft, and expanded into the plexi, so I need to find some steel tubing, and an easier way to make the bushings.

I also worked on the the top deck of the “greenhouse”, which is the glass enclosure that goes over the top of your head  in the cockpit of the aircraft.

Lesson for the week:

The problem: I have an existing screw-hole in the aircraft’s windshield. I am adding an aluminum  strip over where the two pieces of plexiglass meet. How do I line up or measure where to put the hole in the strip when you can’t see the hole after you set the strip  in place?

Two layers of plexi-glass lined up over the nut plate clips (see post ....)

Two layers of plexiglass lined up over the nut plate clips (see post ….)

The solution: Attach a piece of tape perpendicular to the aluminum strip and line the tape’s edge over the center of the screw hole, extending the tape well beyond where the strip will be. Mark a datum line on the tape and measure the distance from the datum to the center of the hole. Put your strip in place and run a straight edge along the edge of the tape, measuring from your old datum line to mark your hole!

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Tape over the center of hole. Datum lines drawn, and distance measured.

marking the outer strip.

marking the outer strip.

Ready to drill

Ready to drill

Well sometimes it does seem like I am continually starting over. But I regularly  get to practice new skill sets, and on this last trip I did score a free lunch from Bob, who has most likely pulled ahead of me in our gentlemen’s race to aircraft completion, (see post). With a little luck from the weather and some help with farm chores, I hope to make great headway toward catching up with Bob over the winter months.

Bob working on the fuel tank of his Piper J3

Bob working on the fuel tank of his Piper J3

Using a hand break to bend the edge of the aluminum strip

Using a hand break to bend the edge of the aluminum strip

hand brake

hand brake

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