The Murphy Builders Site

I'm ready to do the final drilling on the tail cone and am curious if others simply accepted that the pilot holes on the bulkhead corners would keep it square, or if you did something to square up the tail cone prior to the final drilling process.
Thanks,
Jerry Folkerts

Before drilling out to #30, and also before riveting, use a framing square to double and triple check that everything is square.

Even more important, and as another tip, later, when you go to mate the tailcone to the cabin, you have one last opportunity to check that the entire tailcone is square to the cabin and adjust accordingly if necessary--before you drill the mating holes from #40 to #30.

Ted

I would drop a plump line from the center of the bulkhead at the top, to the center of the bulkhead at the bottom. If your table is level, and the plumb bob is making sense, then you are good to go. You can also cross-check by measuring the diagonals and checking that they are the same. I would double and triple check.


Tim

Jerry,

We made some jigs from plywood that followed the corner of the bulkhead and captured the bulkhead about 10" down. Simply use spring clamps to hold the jig(s) in place, it took the bowing out of the bulkheads and made drilling the bulkhead center line easier through the cone skins.

Don't forget to bend (out/in) the mating flanges of the bulkheads to the skin (about 7 deg, if memory serves me right) before drilling and riveting.

Mating the tailcone to the cabin is straight forward, line up the mating holes and cleco.

The time to make sure you have everything "squared", is before you place and drill the corner wraps on the cone...... This step will secure the tailcone as you have it and there will be little you can do to correct it later.

Just my little tid bit of info.

True, when maiting the tailcone, one can't adjust the vertical or horizontal alignment to the cabin structure.

However, one can adjust--if necessary--the side to side or top-bottom alignment. I have seen kits built out of "true" that could have been fixed at tailcone maiting time had the builder had the presence of mind to check before drilling out the maiting surfaces to #30.