Drilling the elevator horns

I have aligned the elevators, See here, done the thing with the metal block with a perpendicular hole through, and drilled to #40 through both horns.

I remain concerned however, that when I drill out to 3/16th, and put the bolt, washers and bearings between them, the alignement will shift.

(I guess my concern is that with the flange bends in the horns the surfaces are not perfectly flat. I have fitted the block as best I know how, but a minute surface error here would surely translate to a significant error at the trailing edge?)

Any tips as to how to be ABSOLUTELY sure this does not happen? Am I worrying unecessarily?

Steve,
There are numerous difficulties with drilling the elevator horns.
I (and others) had a different problem and it is covered in the post:
?Elevator Horn Connection?
http://www.vansairforce.com/community/showthread.php?t=12171&highlight=elevator+horns

Before you drill them would be worth reading the post.
-----------------------
Regarding your specific problem, I did not drill it as per the Vans instructions, because of the problem I had; as discussed in the above post and because of the issue you raise.

This is how I did it and I still think it is better than the Vans method, but I may be missing something. So here it is for your consideration.

As per Vans instructions, I first marked where to drill the holes whilst the elevators were attached to the Horizontal stab and drilled ONE of the holes with a #30 bit.

Because of the couple of inches separation of the horns (when the elevators are attached to the Horizontal stab), I then removed the elevators from the Horiz stab, connected them with a short bolt through the centre elevator horn bearing and clamped them to a VERY FLAT bench, ensuring that the trailing edges were aligned.
I then clamped the elevator horns together.
Now that the two elevator horns were face to face it was a simple matter to drill them square.

Good luck,
Pete.

PS. Don't miss the cricket today.
Pete.

drilling elevator horns

Steve,
I first drilled mine undersize as you did. Then I removed the spacer. Then I drilled the right elevator horn to 3/16 with a Unibit. Then I drilled the spacer block to 3/16 in a drill press so the hole when through the block nice and straight. I then realigned everything and clamped it with a small clamp. I then gently drilled the left horn using the 3/16 holes in the right horn and block as a ?drill guide?.

Good luck,
C. Smith
RV4 #68 - painting

Drilling the elevator horns.

Pete, & #68, Thanks for the responses.

First off, Pete, I like your idea but I presume the rear spar on a -7 is parallel (like a -9). On a -4 it tapers, so without a lot of chocking your neat approach wont work. If it were not for the taper I think I would do it your way.

#68, I guess I will have to do what you suggest - which is the standard way - but I remain nervous for the reasons I said before.

Did not pluck up courage to do it today!

Thanks both for the input, Steve.

PS Sorry you have found the wrong pom re cricket. I find watching the grass grow on the runway far more action packed! (But if there is a match on I have no doubt Australia is winning against the UK.)

Guys
Don't overthink this stuff. The Van's way works!!!!
You've done the hard part with the block and pre drill, just enlarge those to 3/16 and move on.

Good luck

Jon RV4,RV4,RV6A,RV8