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HS spar scratches RV 9

finished match drilling my ribs to the spars on my horizontal stabilizer. When I disassembled and removed the blue plastic, I found these shallow scratches. I believe they came from the brake used in bending the spars in the manufacturing process. The blue plastic was also cut along these scratches. I used mineral spirits to clean the scratches to remove the plastic residue and the photos show what remains. These scratches are very shallow but I can feel them with my fingernail.

https://photos.app.goo.gl/3mi8ho4cX7mFYNrT9

Suggestions?
 
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I received parts with similar marks, and the blue plastic was also cut. Since several parts had the same kind of marks, I assumed this was normal and they were OK to use.
 
what wirejock said, to fix.
remember you are RELIEVING potential edges - not polishing it out [don't take the alclad any more than can be helped].
 
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Just leave it alone. It's fine. Just alclad. Of course a quick call to Van's will put your mind at ease.
 
Very common and normal. Once you start handling enough alclad parts and you will see how easy the pure aluminum layer is to scratch. Remember though a scratch that can catch your fingernail isn't good. Like wirejock says buff with scotchbrite until there is no sharp edges. Not sure if you are choosing to prime (not wanting to start primer wars) but buff and prime takes care of a lot of these things.
 
Thanks

Thanks for the input. I sent a note to Vans and I suspect they will say the same. Having used a sheet metal brake in the past, I recognize that they likely have some rough spots on the foot of their brake.
 
I had quite a few parts like that as well

Of concern is how these scratches intersect many holes. I wouldn't feel good without a little deburring of the scratch edges as others have already mentioned. Any scratch that reaches an edge or a hole seems like too much of a tear-along-the-dotted-line invitation to me, to leave untouched with the scuff pad.

My $.02 only.
 
I had quite a few parts like that as well

Of concern is how these scratches intersect many holes. I wouldn't feel good without a little deburring of the scratch edges as others have already mentioned. Any scratch that reaches an edge or a hole seems like too much of a tear-along-the-dotted-line invitation to me, to leave untouched with the scuff pad.
 
Press Brake

FYI Those marks are from the bottom die of a press brake, very common
 
This is right up my alley. It is likely the scratch is ONLY in the soft clad (almost pure aluminum) finish which is a few thousands thick.... tDrag your finger nail at right angle to the scratch. Does it catch? If you feel nothing, it's not a scratch... If your finger nail catches or feels rough, you want to BLEND it out so you can NOT feel or see it by REMOVING MINIMUM MATERIAL... There are a few ways to blend, but I'd start with a medium scotch brite pad. Work no more than an 1/2 inch either side. The finish will be dull and you should not feel or see any ridge. It may only take a very light swipe of the pad with light pressure to remove the scratch or ridge... WHY? A sharp scratch (even if just in clad) is a stress concentration and can be a crack starter over a long time... however if the stress is low it will likely never crack even with a scratch. High stress parts need more care and attention.

I am assuming the scratch is superficial. With deeper scratches or gouge on thick parts (not sheet metal) you can blend 20 to 1. Say the part is 0.125 thick with a 0.010 deep scratch. You would blend 20 x 0.010 or about 0.20. The total area, size of the blend length and width is also a factor. You can blend more than 10% but requires more knowlege of the part. So if this is 0.040 you would be limited to only 0.004 (4 thousands of an inch). That would slightly be into the base alloy under the clad. It is best to ask Van's if the blend is OK. The know how stressed that area is. You should have some etching and alodine solution and epoxy primer to touch up where you blended. Self etching primer is fine, what ever you have....

Keep in mind the clad is only a few thousands thick and has little strength compared to the alloy it covers... You are not losing strength when clad is blended, but you are removing corrosion protection. Corrosion protection however by clad alone is NOT what commercial makers of planes do. They always etch, alodine and prime, even clad aluminum. This does add weight, and on experimental aircraft you can do as you like. Just be sure to touch up those bare scratches. If you don't want a spot primer job you can prime the whole part. Of course extrusion angles are not clad and should be primed as Vans instructions say, This will restore the finish to prevent corrosion. Clad is for the purpose of corrosion protection because pure aluminum is corrosion resistant more than alloys like 2024-T3 alloy the clad is covering...
 
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