R916 Countersinking Woes!!!

[aarvig]

I am countersinking the R916 AEX wedge. Just like everyone else my countersinks didn't turn out like I would have liked. I set my countersink depth as Vans states to do in the manual...then the rudder skin sits proud of the AEX by 32nd of an inch. If I countersink deep enough for the skin to sit flush to the AEX wedge like it should then the hole in the countersink widens as it intersects with the countersink from the opposite side. AAAARRRRGGGGHHHH! What is the right process here?

 

[Auburntsts]

Depending on the method you are using to CSK, the problem might be that the microstop cage might not be sitting flush on the surface of the AEX wedge. This can lead to a CSK that is "shallow" on one side which could cause the skin dimple not to fit well.

What I did was build a little jig that uses a piece of AEX scrap glued to it. By using the scrap AEX (you can't see it in the photo but it's about an inch long right in the middle of the jig) I can square up the AEX trailing edge to the CSK I chuck in my drill press.

This is not "the" way, but simply "a" way to do it, but it has worked perfectly for me. YMMV...

 

[lorne green]

you're doing fine

The hole does get enlarged because of c/s on both sides. This is pretty normal.
Dimpling the two skins and using your best back-riveting technique along with the application of proseal (or simular product) and a straight edge,
gives us a near flush finish on boh sides of the rudder. There are several posts on rudder riveting w/AEX wedge. I used a buddies' AEX wedge and
layed them face to face netting a 90 degree plain ...ready to c/sink/
Regards

 

[mcencula]

Beware of dimples hitting

On my rudder, I made a jig to hold the pilot of the countersink, so the countersinking went okay, but I found after assembly that the dimples on the left side skin interfered slightly with the dimples on the right side skin causing the skins to bulge out slightly at each rivet location. If you have this problem, too, an easy fix would be to just file the dimples down a little to eliminate the interference.

 

[Av8torTom]

Did mine yesterday...

I countersunk to a depth where the countersinks from both sides JUST met in the middle of the wedge without enlarging the hole. I think that's the best you can do.