how to countersink leg fairing for hinge?

[brian]

I've been installing a new nose gear wheel pant and nose gear leg fairing on my -6A. The drawing (C1) calls for 426 flush rivets 1.5" apart along the trailing edge of the gear leg fairing. I've drilled the holes through the fairing and the piano hinge.

But I don't really see how I'm going to countersink that thin leg fairing fiberglass to get the rivets to sit flush. I haven't tried cutting the countersinks yet, and I will practice first on some scraps, but it seems to me the material is so thin, and the difference between too deep and not deep enough is so tiny, it will be quite difficult to cut the perfect depth, even with a countersink cage.

In hindsight, it seem to me perhaps I should have epoxied the hinge in place, rather than trying to hold it with flush rivets, but I followed the plans & drilled the holes.

Perhaps I can cut the countersinks by turning the cutter in the cage with my hand, rather than a drill, to make sure I don't go even slightly too deep.

What is the experience of others on VAF with this? Did you attach the hinge with flush rivets, as per the plans? Any tips to offer on doing this?

[crabandy]

I followed the plans and countersunk as normal on my RV7 with no issues.

Make sure the hinge is attatched to the fairing to help guide the countersink, I believe it will slightly countersink the hinge and enlarge the hole in the fiberglass but not enough to matter.

I also staggered the rivet holes (top side vs bottom side) so the shop heads wouldn't hit.

[LettersFromFlyoverCountry]

Take your deburring tool with a countersink cutter in it. 1 1/2 turns. Done.

[rleffler]

I was able to countersink the leg fairings on my RV-10 just fine too.

bob

[rzbill]

I did similar to above comments

Stagger the holes.
Hinge clecoed in place to act as guide for the pilot on the c'sink.
Countersink in the deburr handle and used just a few turns by hand.

But.... I used oops rivets. NAS1097 something I think. Its the ones used for putting nutplates in really thin sheet. 3/32 body diameter and a head from an AN2 rivet.

[brian]

Thanks for the tips. I did stagger the holes. I hadn't thought of the c/s cutter in the deburrer. Great tip, and I'll do it that way, as well as using the hinge behind the fiberglass when I do it.
thanks,
brian

[Rupester]

...if you leave the hinge attached when you do the countersinking (as Vans recommends), there's enough material there to center and locate the microstop c'sink cutter. I just did this on my main gear fairings last week ... turned out very nice.
Vans 'structions also say to not fully set the rivets because it will cause cracking around each rivet location in that thin fiberglass. I adjusted my squeezer accordingly ... so the shop heads are a little taller than usual. I don't see any cracking, and finish heads look as good as usual.