Countersinking Pipes?

[RudiGreyling]

Hi Everyone,

I have a query how to countersink small radius pipes as used on the counter-balancing pipe on the rv7 ailerons for flush rivets. I searched my 2 sheet metal construction books but nothing on flush countersinking on pipes.


When one countersink the pipe perpendicular the result is an oval countersunk hole.


The oval hole has 2 diameters: a short one and a long one.


How deep should I countersink the pipe then?

1) So that the rivet head matches the Big Diameter i.e. a small oval hole: which means the long side of the oval will fit the rivet flush, but it will stand out i.e not be flush on the short side of the oval?

OR

2) So that the rivet head matches the Small Diameter i.e. a big oval hole: which means the short side the oval will fit the rivet flush, but it will be to deep on the long side of the oval?

I hope this makes sense...If not I?ll see if I can draw it and attach a picture to explain it better.


Thanks in advance,
Kind Regards
Rudi

[RudiGreyling]

Here's the attached drawing.

Both showing a top and side view for Option #1 and Option #2


Thanks

[RudiGreyling]

Hi guys,

Ok no replies yet?

How deep did you guys countersink the pipes?

Were you happy with the final result when the skin got riveted on, or would you change it?

Please I'm aching to continue the build...

Thanks

[mlw450802]

Rudi,

Do as close to your number two sketch as possible without leaving a knife edge on the under side. Everything will be fine.

-Mike

[Dave_Boxall]

We did close to # 1 sketch & then beat the protruding edges with a small hammer, well more sort of tapped gently really. You'll never spend too much time looking at those rivets so just countersink, bang em in and move on.

Dave

[sf3543]

I agree with Dave. Those rivets are hidden; however, if you notice in your drawing #1 you could shave (file) down the rivet so that it matches the contour of the pipe without reducing the integrity of the rivet, as it is set. Beating down the edges will leave pieces of the rivet on top of the skin, but those could be shaved down.
Countersinking too deeply, as in your diagram #2, would weaken the pipe a little more (Probably not an issue here) and make it difficult to properly set the rivet, since it is down below the top edge of the pipe.
I would do as you show in #1 and tap the edges down, then file off the rivet edges. This would also give you the best finished appearance. (It's been so long since I did this on my RV6 that I don't even remember doing it.)