Plumb Bob for Wing Twist

[KMinor]

I ain't proud. I didn't want to spend $8.00 apiece for plumb bobs. Plus, that thin, nylon fishing line makes for a finer measurement, then I can use them to catch some catfish.
http://i39.tinypic.com/ixs6m8.jpg

[WAM120RV]

Hi

Similar to what I used on my 4, but whats that you are building?

When I did my 4 holes were drilled through the center of the spars for the line to pass through in three places I think. Actually I was thinking about this the other day as someone was trying to deal with wing twist on another thread.

I think what I would do now is work out the centers of the jig uprights and also run line through the tooling jig holes horizontally to absolutely ensure no twist.

[paul330]

I have to admit I invested in a laser line and a digital level - and I think it was well worth it. When you look at the stuff you have to level and line up, the thought of trying to do it with weights hanging off just didn't appeal. Also, by the time you have drawn lines on the floor or whatever, I can't help feeling the errors introduced make it very hit and miss. Maybe I'm missing something - maybe it's just not that critical........

Anyway, after I mounted my wings and clecoed the rear spar, I measured everything up. And measured it and measured it....... I couldn't find more than 0.1deg or 1mm error in ANYTHING.

Happiest day of my life - well, apart from the 3 wedding days, I guess......

[Captain_John]

Nuttin wrong widdat!

You will do the same when you align for wing sweep! Save all that stuff. Don't feed it to the catfishes!

Tip: submerge the sinkers in buckets of water and it will stabilize the lines, especially if you are setting sweep outdoors!

CJ

[KMinor]

Ok, I'm a little bit scared hearing about drilling spars and drawing lines on the floor! My process is to level the main spars width wise, level the main spars length wise by the fishing line across the spar flange rivet holes, then measure with this "plumb bob" on each end. I'm still monkeying with it because when I clamp/bolt down the outboard rear spar end it changes everything so I'm slowly adding shims to that bracket. Clear as mud? Hope that sounds about right. I don't have any experienced help nearby so I'm learning as I go thanks to this website. Steve, its an 8 and I think the prepunched kit eliminates the need for a true jig and alot of the alignment issues you had, but rather a stand for easier access and measuring. I am open to and appreciate suggestions! Thanks for the tip CJ!
Kevin

[dsvajda]

Here's what Steve was mentioning. The plan's for the 6 were pretty specific about the location of the holes.




Dave
RV-6
Waiting for ice/snow to melt

[Larry DeCamp]

Gents, I have restored several tube and rag antiques and built fixtures to set incidence dead nuts ( thats machinist lingo). If you really need some help to get your incidence accurate, call me...Larry 765-505-1160

[paul330]

On my -10, I clecoed the rear spar. Checked the sweep by measuring the diagonal from the tip to the firewall. Dihedral and incidence checked with a digital level.

The laser line came in extremely useful in lining up the gear fairings. I leveled the aircraft then projected the line along the centre of the fuselage and on to the floor. This gave me the datum to square everything up without requiring chalk lines and plumb bobs.