Before I rivet the wing skins...

[NWade]

How are you handling the countersink or dimpling of the control surface hinges?

Kevin - I performed some tests early on with spare hinge material and determined that it's too thin to countersink (not even with a backing plate).

Instead, I've found that the following method works:
Buy a rivet squeezer (it doesn't have to be a fancy model, just a simple/basic one will do)
Buy a good set of pop-rivet dimple dies for the squeezer (I like the ones from Cleaveland Aircraft, but you can get decent ones from a few of the common suppliers).
Align, clamp, and drill your hinge-half to the structure as you see fit. Up-drill with a #32 or #31 bit.
Disassemble, Debur.
Take this hinge-half and assemble it to another hinge-half with hinge wire. Try to keep this hinge set "flat", which will keep the material straight while you work on it.
Use the rivet squeezer & dimple dies to dimple the hinge-half. This deforms the material evenly and you wind up with a nice fit.

NOTE: Many rivet-heads on hinge pieces are "out of the airstream" (often these are the hinge halves that attach to the control surfaces themselves, like the ailerons). For those hinge halves I recommend not dimpling and just using round-head rivets as-normal.

Enjoy!

--Noel

[kevinh]

Ok sounds good. I'll mock up some pieces but your plan pretty much matches what I was thinking. Thanks!

[peter anson]

On the rivet sequence- is there any reason why I can't rivet the top aft skin and then the top forward skin before I flip it over?

Hi Bryan, I think this is potentially a bad way of doing things. The wing box is only stable in torsion when both the top and bottom aft skins are fitted, even if they are only clecoed. It will work if you make sure that everything is square again when you turn it over, but if you build the wing vertical, nose down, you can just sit the spars across a couple of trestles, square it up and attach the skins. Once the rear skins are attached, even with clecoes, the structure becomes very strong and can be handles easily without risk of mis-alignment.

Peter
Sonex 894

[Bryan Cotton]

Peter,
You have good points. I agree the wing box needs the top and bottom skin to be rigid. I had planned to align, rivet top skin, rivet top of forward skin. Then I would flip and level/ true again. I see two benefits to my plan.
1) two less flips in the sequence
2) a chance to locate the optional holes that mount the center of the wingtip. I need at least one for my nav lights.

[sonex892.]

Bryan
If your wing is all true and level with no twist when ready to rivet. I doubt you will have any problems if riveting both rear and forward skins together prior to the bottom. If anything I reckon the front skin also being riveted would make the one skinned structure more rigid when flipping. Besides the shape of the wing has already been set previously during final updrilling.

However you end up doing it, I definitely recommend riveting the top of the leading edge before the bottom. I wish I had. My bottom leading edge was riveted first and looks much nicer than the top. ;)
Steve
Sonex892
VH-ZSX 195 hrs

[Bryan Cotton]

Steve,
Makes perfect sense. That is one reason I plan to rivet the top LE first. If the rivets on the bottom skin make a little dimple it is less of a big deal aesthetically as well as aerodynamically.