[FlyBoy8]

The scratches around the rivet holes in this VS skin occured when I was trial fitting the skin to the structure. I guess I wasn't being gentle enough. I'm a little paranoid about scratches after reading in the manual that all scratches should be removed etc. I would appreciate comments from experienced builders on the best way to handle this. Thanks in advance.

 

[ijustwannafly]

I would also be curious to hear what people think about this. I just walked in from the shop after doing some deburring from the VS808PP spar doubler that you probably just finished working on also.

That piece is so thick that it has major tooling marks on it and after closely examining it even after deburring and filling the big tool marks down from the shear I'm left with little pits in the metal. Im afraid if i keep on sanding and sanding until they disappear I'm not going to have any parts left

How did your doubler look? I think my skin has a few scratches like that also and was thinking the same thing you are. Lets see what the experienced guys think.

 

[aeroaddict]

Depending on depth, I would scotchbrite the areas and prime.

A way to check depth is to drag a fingernail over the scratch and if it catches then the scratch is somewhat deep. This is all subjective of course.

Main thing; remove scratch (scotchbrite, sandpaper, file, etc.), no sharp edges remaining, but not deep enough to significantly reduce material cross section. Scratches with sharp edges can create crack initiation sites, and also reduce corrosion protection due to the penetration of the alcad (hence the need for priming).

 

[ijustwannafly]

I don't think i have come across a scratch in the very fragile aluminum that i can't feel with my fingernail. It seems at least in my experience that if you can see it, you can feel it when it comes to aluminum.

Sorry, not to highjack the thread from the OP. Im just also interested in this subject

I have parts right from vans that have scratches from tooling that would require significant metal removal to get out. Should we be sending these back to vans then?

 

[A5555]

structural?

I don't believe these scratches are as detrimental as a scratch on a primary structure such as a wing spar.

 

[bruceh]

Good deburring and smoothing of all of the edges of the ribs will help alleviate these preassembly scratches. Run a file down each rib edge to get rid of the little flashings left by the punch presses, then run the edge over a small scotchbrite polish wheel to get them smoothed out. The skin scratches are pretty normal, so don't worry about them unless they are really significant. Hit the scratches with a scotchbrite pad, clean the area with acetone, then shoot some primer or alodine on the scuffed area. If you can still feel a definite catch on your fingernail after that, then you might have a deep enough scratch to be concerned about.