F606 and Shims

[JanRV6UK]

Question regarding the F-606 top 1/2 of the bulk head .. how much did you have to shim to get a nice line in the top skin ? My dimension from the top longeron to the top of F-606 is spot on - The top lines up perfect with the 3 rear bulkheads ... but when you go down the side, it gets progressively worse - right next to the longeron my F-606 is close to 3/16 inboard of the longeron.

What is out there ??

 

[ChiefPilot]

Question regarding the F-606 top 1/2 of the bulk head .. how much did you have to shim to get a nice line in the top skin ? My dimension from the top longeron to the top of F-606 is spot on - The top lines up perfect with the 3 rear bulkheads ... but when you go down the side, it gets progressively worse - right next to the longeron my F-606 is close to 3/16 inboard of the longeron.

What is out there ??

Mine wasn't quite that bad - but I did use a number of shims around the sides of F-606. I used shims made from 0.20" sheet but next time I'd consider something like "Liquid Shim" that I've seen other folks here mention.

 

[WenEng]

Shim what is necessary for smooth overlap

When I had my top skin clecoed on, there was no need for a shim on one side and a 1/2 inch long shim on the other side made from .032 at the lowest F606 rivet. 3/16 will force you to shim more but that's easier than resizing the bulkhead, eh? Also consider positioning the lowest hole on the F606 flange up higher away from the longeron to ease that transition if you haven't already drilled them. The end of the flange will try to conform to the skin right there.

 

[JanRV6UK]

Thanks for quick comments - I am thinking of cutting of the top half of the bulk head and make a new one - The rear half (below the longeron) are already riveted in place. I had to use 2 strips or .032 to get a smooth line to the rear bulkheads.

Currently I am doing a visual check with a long straight edge - and the gap at F606 is considerable - right at the longeron - it does get "better" as you go up the sides .. but its not "good" until you reach the 'J' stringer. I think I will lay out the two top skins and see how "bad' it all looks .. before I start cutting things off .. The liquid shim idea is interesting.