Damaged dimple on a skin, is it fatal?
 

Hi Guys ,

I need your educated opinion here, we damaged a
dimpled holes a bit, what do you think is it so
bad that requires a new skin?

here is what happened:

We just started to scuff the VS skin (VS-801PP)
as a preparation for priming / coating.

Accidentaly we applied too much force on the inner side where dimpled cone is.

As a result there are a few dimpled holes that are a bit larger now: (about 0.15mm) and they are a bit flatened , you can see the results on pictures attached. Also
have to add here that the front side of the holes is
completely fine.

Please advise if it may cause a problem or may affect the structure strenght.

The big question now is , whether we can continue with that skin or we have to order a new one.

Looking forward for your recommendations.


check that album for illustration:
https://imgur.com/a/Oes7Ocq


Blogging my RV14 here:
https://bit.ly/2PzjPzS

The general rule is that you can adjust a dimpled hole one time, either reversing it (if you dimpled the wrong direction) or re-dimpling. After that, the aluminum is considered fatigued and needs to be replaced.

I would try to dimple them again first, but just once. If that doesn't fix it for you the best solution is to just get another part and consider that one practice .. I had lots of "practice" :D

Vans is the final say, but these aren't 'reverse dimpled'. I'd say touch them up with dimple dies again and let the rivet do its job, maybe upsize one length rivet.

EDIT: The heavy mechanical scuffing method may lead to more issues and would change my recommendation.

Personally I would go to 1/8" rivets in these holes. You are using way too much scuffing force. Very little scuffing is needed, especially if you are using a self-etching primer.

Thanks guys, the mail to Vans been
sent. Your ideas are very interesting.

How often people go to 1/8 rivet
while killing 3/32 holes?

Process
 

Consider changing the process. Scuff before dimpling.

How the heck did you scuff the skin hard enough to both flatten a dimple and enlarge a hole? How is this even possible? What are you using to scuff ?

Oops Rivets..
 

..have the same head as an AN-3 but the shank of an AN-4. However, if this condition is over a whole lot of holes, I'd start again, since you've hardly begun.

...and
 

And remember, if you need to go up a shank size, you can use "Oops" rivets. They have the same sized hand as the specified rivet but the shank is one size larger...

That one. Wont do it again.
https://imgur.com/6j97R5H