The mod to the radius of aileron bell crank necessitates the boring out
the hole through the wing, to get a half inch displacement. As it is 2m
long the suggested method of "broomhandling" with an abrasive on the end
takes hours, and it well nigh impossible if the tunnel wall has been
reinforced by bid. It takes perhaps half an hour to make up a tool to do
the job in 5 minutes !
You need two lengths of 1/4" rod as long as you intend to make the hole
(you don't have to bore the full length), a guide plate shaped to the
original hole shape (one for each wing), and a cutter.
The guide plate can be plywood for one off, though 1/8" al. or steel will
last better). A hole in the middle takes a screw for mounting it on the
end of one rod (for pushing), which thus needs a tapped (or hole for self
tapper) hole in the end. Another 1/4 hole in the plate is offset to place
the cutter where you want it, mounted on the end of the second rod which
is for your drill at the other end.
A suitable cutter is the one most DIY shops carry for making the 35mm
blind holes for cupboard door hinge recesses. (I tried a Permagrit wheel
with abrasive paper stuck to the end, but this keeps coming off whatever
the adhesive, and you definitely need some cutting action on
the flat face of the disc.
The simplest attachment of the cutter is to saw both the cutter and the
rod along a diameter for 1/2", and screw the overlap together, but
welding, or a socket and grub screws is neater if you can do it. Attach
the drill to the cutter rod and away you go. You will meet some
resistance at the cross plys but the rest is literally like going through
butter.
Anyone near enough to borrow my version is welcome to collect it, but
it's a bit unwieldy for the post.
gemin
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