Originally Posted by Capflyer
I am building a HRII and just started the center section. Trying to figure out the best way to match drill the already drilled spars and W-420 spar splice plates to the center section F-404's. Open to hearing all suggestions.
The other suggestions from Scott and David are certainly options. Another one is to NOT drill any of those close tolerance holes, but simply extend the outboard portions of your existing RV-4 parts, i.e. the #3 and #4 bulkheads.
Here's a PDF with photos
of how to do this. It's probably the easiest of the options presented here.
Be sure to maintain the fore and aft relationship to the spar, probably by inserting the spar, before drilling the "U" shaped side plates. Same for the bottom plate. Afterall, the spars must fit inside when you're done... and the bolts must go in the holes!
Even if it's not your final choice on how to do this, I think you'll find the info useful.
(Note: #3 is the forward face of the 404 bulkhead.)
(Note also... the HR2 uprights are parallel to each other, while the F1 parts are staggered a bit. IOW, the rear uprights are as bit closer together, L&R. That change was made to help the one piece F1 side skins lay down better.)
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