Dimple Depth for HS Ribs to skin

[jdeas]

I know I'm being a worry wart but I would like to get through the first week without ordering replacement parts

I am working on the HS and Vans guide shows using a dimple depth .005 below rivet flush for underlying structures.
When assembling the forward HS spar, there are four countersunk/flush rivets. I counter sunk to .005 but that didn't seem to be enough depth for the spar to sit inside the matching countersink. After some test rivets in some scrap it appeared that .01 would work better as the Spar sits flush with the support Alum angle.
With that out of the way I am now starting to dimple the HS ribs.
Is this perhaps the area where dimple depth should be .005 below flush (when a rivet is inserted into the dimpled rib)? Should the dimpled skin sit flush on the rib when the dimple depth is correct or should it be slightly above before riveting?

 

[G-force]

Dimpleing the ribs or skins are not adjustable, dimple it as tight as the dies will let it go. When countersinking, I had the same problems as you. It did many test pieces and basicaly I found it boiled down to the fact that if you countersunk so the skin sat flat, it was too deep. The process of riveting seems to pull the pieces together. Your .010" below flush sounds fine, I think I used the width of the female dimple as a guide. IIRC, the width of the countersink for a 3/32 was near .205" wide, and 1/8 was .245" wide.

 

[cwreeves]

I've actually called Van's several time concerning the depth of countersink that accepts the dimple. If you are a carpenter you'd would think skin to rib, spar or skin to skin contact is important and apply that logic, however Van's say's it's not. The countersink should be cut just deep enough to see the cut edge when a rivet is installed. This would put the depth at about .005 below the surface. I've used this logic during my building process. Hope this helps.
Charlie