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Smudge around dimples DRDT

toddzz

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I'm not far into my RV-14 build. My DRDT has started producing a "smudge" with each dimple, on both sides of the aluminum. (pic attached)

While visible, the smudge isn't palpable with your finger. I've tried adjusting the DRDT, reading the instructions again, with no luck. Looking for opinions, thanks in advance.
 

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The sign of a good dimple

Dimpling "smudges" are a good sign, though they should really be the full circumference of the die. This indicates adequate pressure during dimpling and will result in smooth skins after riveting. There's little risk of over-dimpling, whereas under-dimpling won't end up looking good.
 
More pressure

I think you need to adjust for more pressure. My best dimples resulted in circles surrounding the hole. Best pix I could find :
 

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I'm not far into my RV-14 build. My DRDT has started producing a "smudge" with each dimple, on both sides of the aluminum. (pic attached)

While visible, the smudge isn't palpable with your finger. I've tried adjusting the DRDT, reading the instructions again, with no luck. Looking for opinions, thanks in advance.

This is different than a "witness mark", a faint, to not so faint concentric circle, the same diameter as the die. The "smudge" shown in your picture is caused by the dimple dies/frame of the DRDT-2 not being perfectly square to the material being dimpled -- said differently, there's a little more squeeze on one side than the other, causing a bit of deformation on one side.

I'd take a piece of test materiel, drill a bunch of holes, then determine which side of the die (if any) is proud, or if the die holder hole is true, the down rod is true, etc etc..
 
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This is different than a "witness mark", a faint, to not so faint concentric circle, the same diameter as the die. The "smudge" shown in your picture is caused by the dimple dies/frame of the DRDT-2 not being perfectly square to the material being dimpled -- said differently, there's a little more squeeze on one side than the other, causing a bit of deformation on one side.

I'd take a piece of test materiel, drill a bunch of holes, then determine which side of the die (if any) is proud, or if the die holder hole is true, the down rod is true, etc etc..

Good comment. Also slightly rotate the die to see if anything changes.
 
You guys are going to send the poor guy into "paralysis by analysis". They looked fine to me, and they're going to look a heck of a lot more "smudged" by the time they get cleco'd together, riveted, handled during assembly, scuffed for paint prep, etc.

I say just make sure your part is flat (square to the dies), and build on. Set some rivets, see how they look. Dollars to donuts they're fine, but if not, mess around and try different pressures, etc, until you're happy.
 
Exempli gratia...

Here's a properly smashed dimple, perhaps overly so, using the DRDT-2...
 

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