Gee I'm surprised none of the resident experts has responded to your
question yet. Especially since it begs for a smart-axx answer


Simple, use a hole finder.
Same principle at the commercial ones that you buy.
Overlay a thin piece of metal over the horn's shaft to mark the holes and
fasten at a point below what is being inserted in the rudder tube.
Slide the horn and into the rudder and keep the hole finder on the outside.
Wa lah you have the hole location.

I'm not sure what degree of precision you are desiring.
Use a small drill to open the hole in the rudder tube then use appropriate
piloted or non-piloted reamers for final sizing.


wrote in message
ups.com...

There are a few accomplished and talented brains here that can help
with this. We have a tailwheel steering control horn with holes
already drilled at right angles through its long shaft for two AN-3
bolts-- to fix it inside the rudder's vertical tube. Now when the
shaft is inserted up inside the 4130 tubing of the new rudder, what
would be the best way to drill the rudder's tube accurately, without
missing the holes in the shaft or wallowing them out? Those two AN-3
bolts are in shear and of course fasten the tailwheel steering horn to
the rudder. We want precision, and no slop. The old rudder's holes
looked like hell.

I can see where the problem was encountered elsewhere and the holes in
the tailwheel steering horn were elongated, then welded back and
re-drilled-- not such a good idea since the control horn is aluminum
alloy.

Ever seen that little mag-pecker device that lets you find a blind hole
you need to drill through to? There is a magnet centered in the blind
hole, which a sharp needle points to, making a prick in the precise
spot where you drill. Well, I don't think it will work here, but bet
you could make one that would.

TIA and apologise for all the Freudian terms.



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