a riv[e]ting topic

Robert Ollerton rollerton at gmail.com
Fri Jan 12 13:42:52 CST 2007


thats good stuff!

On 1/12/07, Robert <gstreet at indy.net> wrote:
>
> Hello All,
>
> >
> >While I was checking the spelling, I notice that wikipedia mentions
> >another name for pop rivets is blind rivets.
> >
>
> I _love_ Wikipedia, but it certainly has its share of errors. Please:
> Never equate
> pop rivets with "blind" rivets. Blind rivet is a sort of generic term --
> meaning that
> it's a form of rivet that can be used even though you do not have access
> to the other
> side of the rivet. Blind rivets are used on commercial aircraft, but only
> in relatively small
> quantities -- and -- each catagory of (blind) rivet is carefully chosen to
> perform a certain
> task. Most times, when we install blind fasteners (rivets fall into the
> broad catagory
> of fasteners), we have to get Engineering approval. Most installations of
> blind rivets are
> actually considered temporary. They will usually be removed during a Heavy
> Maintenance
> Visit (often several years later).
>
> Pop rivets fall at the very bottom of the rivet catagory. Pop rivets are
> never used on commercial
> aircraft structure, although I've used a lot of (a certain higher quality
> catagory of) them to fasten
> things like nutplates (all they are doing is holding what amounts to a
> nut, in place, while a bolt is tightened).
> Once tight, the bolt is tight the rivets are meaningless until you need to
> remove the bolt again. If the "pop" (type)
> rivets don't hold, then a veritable stream of cursing insues, while you go
> and try to find the right drill bits
> to remove the offending nutplates. Then, the little buggers almost always
> spin while you curse more and
> try to get a small pair of ViseGrips on the bottom of them (often very
> difficult due to space constraints), so you
> can smash them into submission, while you continue to drill them out.
>
> "Cherry-Max" rivets are a very popular form of blind fastener (in this
> case, blind rivet). They have a solid
> core of wickedly hard stainless steel that remains in place as the rivet
> is "pulled" into its compressed final
> product. Not only are they relatively heavy, they do not expand in the
> same way that solid rivets do -- plus
> you now have a dissimilar metal situation.
>
> Speaking of pop rivets: There is a kitplane (an excellent work horse of a
> plane) that makes use of thousands of
> closely spaced pop rivets. I used to be able to recall its name off the
> top of my head, but this library computer
> will not allow me to open another instance of my browser (to search google
> and figure it out). It was a sort of ugly, boxy, utilatarian looking plane.
> It was so "ugly" that it was actually very cool!! It's supposedly nearly
> "indestructable."
>
> Oh, BTW, "regular" solid aluminum rivets are only very slightly smaller
> than their correctly drilled, and in some
> cases, reamed holes. When the are compressed (bucked), they expand and
> tightly fill the hole. It's certainly an
> impressive art to get a properly shaped "bucked" head (also called "shop
> head"). If the bucked head is smashed
> too much or "leans" over, you've got to remove them. Technically, you are
> supposed to go to the next larger
> size because the material around the hole is now work hardened. If
> everyone actually removed ever screwed
> up rivet, there would be little hope of repair at a later time (because
> you don't have much leeway as to size).
> I'm pretty sure that that's how ships remained fairly water-tight. The
> final result of solid rivets are not always perfect. Upon close inspection
> of any commerical airliner, I can find dozens of leaking or "smoking"
> rivets. Technically speaking, they should be replaced. Realistically, it's a
> case of "what are you going to do?" I did a lightning inspection on a 757
> that said they were hit on short final. It was raining and miserable (and
> very dark). It wasn't until the last section of inspection that I realized
> that I'd forgotten to check a few antennas. One thing led to
> another, and we eventually found way over 100 affected rivets (and
> outright holes). The plane was taken out of service for a couple of months,
> but I saw it again (with lots of very large rivets, which were used to
> "fill" some
> of the lightning strike holes).
>
> Always choose the correct rivet for the job(!!!).
>
> Regards,
> Robert Greenstreet
>



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