Plumb bobs?

[aarvig]

After moving my shop 3 times in the last year I am finally getting the wings set back up in their stands in a small room in my basement. Its tight but I will be able to build both at the same time.
Correct me if I'm wrong but are plumb bobs necessary to level the wings? Won't they self align once the skins are all on? Basically, I placed a level across the spars on both ends and adjusted to level and left it. I've drilled all the holes in the skins and now i'm wondering if I should've plumb bob'd everything. Wouldn't it arrive at the same result as a level?

[RV7A Flyer]

They'll self-align *fairly* close, but by using plumb bobs and careful measurement, you can remove essentially any twist in the wing prior to riveting. We found about 1/16" twist end-to-end when the main spars were on the stand and the skins clecoed in place. Removing the clecoes, adjusting the rear spar ever so slightly and then reclamping, then re-clecoing on the skins removed any deviation prior to riveting.

[wjb]

After putting my wings in the jig and leveling the arms that hold the spar/end, I plumb-bob'ed he inner and outer rib and made a slight adjustment to make both the same as I could measure (measured from a hole on the main spar (datum) to a hole on the aft spar), and then clamped the aft spar down tight. I was able to take out just a bit of twist, and it made for a more solid structure to rivet to, with all four corners constrained.

[N546RV]

Ditto the above. I found slight amounts of twist in both wings on the stands, maybe 1/16" difference at the rear spar. I have Greyling-type adjustable stands, so I just tweaked the inboard arm to remove twist, then clamped the rear spar into place.

[wirejock]

+1 on the twist and use of plumb bobs. I used them before riveting each part. Before leading edge, top skin then again before bottom skin just to be sure I didn't rivet in a twist.

[airguy]

Originally Posted by RV7A Flyer

They'll self-align *fairly* close, but by using plumb bobs and careful measurement, you can remove essentially any twist in the wing prior to riveting. We found about 1/16" twist end-to-end when the main spars were on the stand and the skins clecoed in place. Removing the clecoes, adjusting the rear spar ever so slightly and then reclamping, then re-clecoing on the skins removed any deviation prior to riveting.

They *SHOULD* align just right, and the Vans instructions tell you to hang plumb bobs to check and see if they do - but the interesting thing is that the instructions don't give a flippin' clue as to what to do if they don't. Luckily mine did, and I didn't have to chase down that hidden road...