Locating Spar attach holes (any tricks you used)

[southwind32]

I replaced the front spar on my build so have to rig the wing and drill the attach hole. The rear hole is already there.
I know you have to do certain measurement to locate the hole in the spar for drilling............I'm wondering if anyone used any special techniques that would aide in precisely locating this hole other then just using a tape measure.
Thanks
Brian

[Geowitz]

The placement of the hole is more a result of positioning the spar perfectly in line with the other front spar rather than any specific measurements with a tape measure. Many use a string line to ensure a straight leading edge along the entire length of the wingspan. I actually found a 10 foot straight edge and clamped it to both leading edges in the middle forcing the front spars to align. Then the trick is to make sure you keep the hole that you are drilling aligned with the fuselage frame hole. A hole finder, bought or made out of scrap is essential here to get started. Then you can finish the hole with a small file to perfectly match it to the frame pin hole.

[72chevy]

This looks handy.

[David47]

Concurr with Geowitz. I've recently match drilled my wing spars to the fuselage using a very similar technique. But in your case, as it sounds like a repair, to ensure correct wing sweep alignment, and to ensue symmetrical dihedral and washout, both wings should be installed and checked against each other, with any adjustments required made at the strut adjustable rod ends.

[southwind32]

Concurr with Geowitz. I've recently match drilled my wing spars to the fuselage using a very similar technique. But in your case, as it sounds like a repair, to ensure correct wing sweep alignment, and to ensue symmetrical dihedral and washout, both wings should be installed and checked against each other, with any adjustments required made at the strut adjustable rod ends.

Thanks, I plan on installing both wings and checking all measurements.

[efwd]

shy of possessing one of those cool tools that would make it a breeze to drill the hole, I used a dremel bit verses a file. The bit I used was that bit that has very steep flutes. I believe its designed to take side loads. After I drilled the hole and found it a bit off center I found the file was taking way too long to get the job done. The Dremel bit took about 90 seconds to remove the margins.
Eddie

[David47]

......After I drilled the hole and found it a bit off center I found the file was taking way too long to get the job done. The Dremel bit took about 90 seconds to remove the margins.
Eddie

Similar case here too Eddie ....One of my holes was also off centre and I suspect others will have had similar problems. Even with a hole finder it's not 100% accurate. I ran the drill through each hole couple of times to slightly o/s the hole. This allows easy removal of the forward pins when swinging the wings, and also provides a running fit at the rear bolt holes for hinging. Although it would be better to have a snug fit, the reality is that if you are trailering your aircraft to the field and therefore swinging the wings, you need a small amount of freeplay in the holes - but not too much.

Brian, also, the ss7 manual notes that you should bond Rib #1 to the spars with the wings in place. This ensures the you maintain the correct spar alignment with the fuselage pickup holes. Totally recommend you do this at the same time as you drill off the front spar. I know this because I tried another way and .... I mentioned before I had a hole slightly out of alignment .... well enough said. :rolleyes:

[n85ae]

1 - Cleco two layer of aluminum together. Drill a #40 pilot hole through both
set one aside.

2 - Drill the other one to the spar attach bolt size.

3 - Put a bolt though the spar attach, and align the drilled aluminum on it.

4 - Duct tape it to the airframe.

5 - remove the bolt

6 - Cleco the piece with the pilot hole to the piece duct taped to the airframe.

7 - Put the wing on. You will now know the exact location for the pilot hole.

Jeff

[southwind32]

1 - Cleco two layer of aluminum together. Drill a #40 pilot hole through both
set one aside.

2 - Drill the other one to the spar attach bolt size.

3 - Put a bolt though the spar attach, and align the drilled aluminum on it.

4 - Duct tape it to the airframe.

5 - remove the bolt

6 - Cleco the piece with the pilot hole to the piece duct taped to the airframe.

7 - Put the wing on. You will now know the exact location for the pilot hole.

Jeff

This sounds like a good and easy way............thanks.