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Dimple P3 Hinge?

mturnerb

Well Known Member
Building my trim tab it occurred to me I might be able to dimple the spar and hinge as opposed to countersinking the spar - it's kind of thin to countersink for dimples.

I tested dimpling a piece of scrap "P3" hinge and it seems to work well on the DRDT-2 with no distortion of the hinge material.

Interested in opinions on why this won't work / why countersinking the spar is preferred.
 
DONT DIMPLE HINGE

I did that once. The first one or two look ok but by the time you do them all it ends up curved and way distorted and unusable. Countersink in the only option here. It will save you from ordering new parts.
 
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When you countersink the spar, I put the rivet fan on the backside to give the pilot something to be guided by. You can also back it with mdf, to a strip of aluminum with holes for the cutter pilot. Don’t countersink it without something behind or it’ll wobble and make a mess! The plans say to countersink it, and explain that because it’s sandwiches, that’s it’s ok. Don’t overthink it..
 
I did that once. The first one or two look ok but by the time you do them all it ends up curved and way distorted and unusable. Countersink in the only option here. It will save you from ordering new parts.

Interesting - I did a fairly long piece as a test with no issues at all. Very slight curve but easily formed.

New question: if material can be dimpled without significant distortion, is there any structural reason not to do so?
 
When you countersink the spar, I put the rivet fan on the backside to give the pilot something to be guided by. You can also back it with mdf, to a strip of aluminum with holes for the cutter pilot. Don’t countersink it without something behind or it’ll wobble and make a mess! The plans say to countersink it, and explain that because it’s sandwiches, that’s it’s ok. Don’t overthink it..

Thanks. I usually use a piece of wood with #40 size hole behind it, but mostly concerned about the knife edge as you note.
 
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