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Countersink rear VS doubler question.

PatMac

Active Member
Good evening...
Countersunk the rear spar doubler but it does not sit perfectly flush w/ the spar now. The countersinks seem to be set perfect for the rivet but when mated w/ rear they don't seat perfectly.
Hate to countersink any deeper... Tx in advance.
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I had the exact same question on my -9. Make sure you're countersinking to .007" beyond where the rivet is flush. That's what the manual calls out as the sweet spot for these scenarios. Any less and you'll get interference from the dimple, but any more and you start to get into territory where you have some space in the rivet joint itself that you don't want. Somewhere in the millions of posts on VAF there are pictures from Van's that illustrates this and how they came up with the .007" determination.
 
Even after the 0.007" extra skelrad appropriately mentions, it may seem like the doubler isn't sitting completely flush. That's okay! No need to go deeper still as that depth will result in optimal mating surface when riveted. That's what I remember reading anyway.
 
Great help. Tx
Any idea what each tooth on the countersink cage is equal to depthwise? I remember reading it somewhere but my brain is mush today...
 
Great help. Tx
Any idea what each tooth on the countersink cage is equal to depthwise? I remember reading it somewhere but my brain is mush today...

Assuming it's a standard countersink cage, each tooth is usually .001"
 
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There is a whole section on working with sheet metal and general Oopsies and fixes that might be helpful for the new builder.

Page 22 of the General construction PDF in the WIKI
 
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