Is it permitted to sand rivets? 4

[aerostructurejoe]

Is sanding rivets allowed for a smoother surface and how much is allowed to sand ?

 

[rb1957]

do you mean like shaving the CSK head with a micro-shaver, 'cause it's a little bit proud ?

or attacking the panel with some 100 grit on a disc sander ?

another day in paradise, or is paradise one day closer ?

 

[WKTaylor]

ASB..

EVERY rivet installation guide/specification I'm aware of, specifies a minimum installed head and tail height for every protruding head rivet size. As long as the sanding is relatively smooth [Ra=125 microinch or better] and does not cause the head-or-tail height to fall below spec minimums, then this is generally OK... assuming the rivet installation is otherwise 'good', IE: tight, tail bucked straight no weird cocking, no gaps, etc.

CAUTION sanding removes the rivet's protective finish [alodine or anodize]. In this case application of alodine [chromate conversion coating 'CCC'] and primer and top-coat fiishes are STRONGLY recommended to prevent localized corrosion on the rivet head. But... hey... your crazy sanding probably ground-off the cladding and finishes from the surrounding skin, also.

CAUTION.
Be careful about sanding across aluminum surfacces onto steel fastener headss: tiny bits of steel [sanding particles] can become imbedded in the adjacent aluminum skin... massive corrosion+rust-pitting is guaranteed in these areas.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true.
o For those who believe, no proof is required; for those who cannot believe, no proof is possible.
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
o Learn the rules like a pro, so you can break them like an artist. [Picasso]

 

[berkshire]

aerostructureboy,
Light sanding within the limits mentioned by WKTAYLOR, is allowed, when incidental to painting operations. Deliberately sanding the heads for a lower profile is a no no, and will not buy you very much with raised head rivets.
Micro shaving countersunk rivet heads with a special tool, to get them flush to the surface is allowed, again subject to the manufacturer of the aircraft's specifications.
B.E.

You are judged not by what you know, but by what you can do.

 

[tbuelna]

is it allowed sanding rivets for a smoother surface and how much is allowed to sand ?

Allowed by who? And what part of the rivet will be sanded?

Shaving of flush rivet heads that protrude above the adjacent surface beyond a certain amount was common practice on aircraft aero surfaces at one time. But rivet design and installation processes have improved to the point where shaving is not needed much. I have never seen a manual abrasive material removal process like sanding used to perform this task.

Frankly, if your installed flush head rivets are protruding significantly above the adjacent surface, then you need to control your countersink process more tightly. This condition is not good, since it means your rivets are likely not installed in a manner that allows them to perform properly.

 

[dgapilot]

I remember having to shoot new rivets in the upper surface of a Bonanza wing 'cause the paint shop sanded all the heads off! Make sure who ever is doing it knows what they are doing.

 

[aerostructurejoe]

I'm talking about head on flush rivets, they're use to instsall nutplates and it's pretty common to sand them because a coating, so i had that doubt. thank you all.

never accept anything for true which you don't clearly know to be such

 

[tbuelna]

I'm talking about head on flush rivets, they're use to instsall nutplates and it's pretty common to sand them because a coating, so i had that doubt. thank you all.

I don't recall ever seeing flush rivet heads used for nutplate attachment being sanded to provide a "smoother surface". The flush head rivets used to attach nutplates are not a critical application. And as long as the head does not protrude excessively such that the mating part does not lay flat against the surface, it does not present a problem. In fact, I recall that the holes for the nutplate were usually drilled/countersunk, the panel was alodined or primered, and then the nutplate was installed. This provided the best level of corrosion protection.

 

[rb1957]

IMHO, it's pretty crappy workmanship, to stuff up a/nuts rivets. is there a big stack up (high t/d) ?

another day in paradise, or is paradise one day closer ?

 

[rb1957]

"sand 'cause of a coating" ... ?? ... like 'cause paint/primer doesn't adhere to the coating ?

or 'cause the csk drill didn't account for the coating, and so the head is a couple thou proud ?

another day in paradise, or is paradise one day closer ?