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Spar blocks

pappa

Member
Starting on fuselage. My plans say to make blocks. They MUST be 1.438 inches to match the thickness of the spars. Just happened to put a dial caliper on the spars. Well, they all read thicker, The thickest reading.....1.448. .?????. How once everything is locked down and riveted, can a solid piece of metal that is larger than the hole it is supposed to go in, actually go into that hole. So, how did you'all do it. Your thoughts are greatly appreciated.
 
There’s more flex in the center section than you think. When building up my F-704 bulkhead I used a set of blocks from a previous RV-7 builder and even added a couple of layers of masking tape to give myself a little cushion. When I measured the center section and spar stubs in preparation for mating the wings to the fuselage for the first time I was horrified to find that the spar stubs were 10-15 mils thicker than the space in the bulkhead. I did some research and found that several builders before me had the same issue and ended up not having a problem mating the wings. Per the manual I lightly beveled the ends of the spars and greased them and the center section. It took a few minutes of jockeying to get the spars lined up with the center section, but once we did the spars slid right in.

http://www.mykitlog.com/users/displ...r&project=2052&category=7733&log=251539&row=9
 
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I used plywood. Doubled the pieces shaved to required thickness and left there for couple years. Drilled them later to secure the fuselage while transporting to the airport.

 
I had a scrap piece of thin walled electrical conduit. I cut 4 pieces to rough length with a tubing cutter, then chucked it up in the drill press and filed it down to the correct length. Measured everything with calipers until it was a perfect fit. Wood will potentially change its length with humidity. These spacers worked great and didn't take up any unnecessary space in the spar carry-through area.
 
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