Potential Major Problem...need opinions

[Andy Walker]

Here's what I just sent to Sonex tech support:


This fuselage construction is kicking my butt. I measure everything very carefully, cut and drill as accurately as I can, and I still end up with problems. Here's the latest: I'm on page SNX-F11, and I'm done putting things together and am updrilling everything. When updrilling the splice plates, which I thought were golden, I realized that my right vertical splice plate holes are pretty off center on the angle. Here's the pic (with #30 holes):



And here's what it looks like with the plate in place:



The other side is a little off center, but not as bad:



Once these holes are updrilled to 3/16" they will be closer to the edge of the longeron angle. Here are the options I see:

1) It's fine, forget about it and carry on.

2) It's a total disaster, re-make the longeron and splice plates, and deal with all the other parts that have to be re-mated along the side.

3) Add an additional hole between the existing two and put a third bolt in place (drilled lower, obviously). This has the problem of possible interference with the lower splice plate bolts/nuts.

4) Re-make the vertical splice plate, but make it longer, drill out the closest rivet and make it a 3/16" bolt hole as well.

5) Combine #3 & #4.

6) Throw the damn thing out into the street and let it rot. :x

Sigh...

[MichaelFarley56]

I know it doesn't help much right now, but I would probably wait and see what the factory says. You may still have enough edge distance there once you up drill to 3/16", but I can't remember what is needed.

We've all faced issues...just keep at it and see what Kerry suggests. Let us know!

[sonex892]

Andy, Its probably ok. SNX-F11 detail B at the bottom centre of the page, clearly shows these holes are not on the same line as the rivets. Bolts are 3/8" from the angles edge. The rivets I think from memory are on the centreline of the angle. Did you chamfer the internal corners on the splice plates where the plates meet each other?
Steve
Sonex 892
3300 TD 80hrs

[Andy Walker]

Andy, Its probably ok. SNX-F11 detail B at the bottom centre of the page, clearly shows these holes are not on the same line as the rivets. Bolts are 3/8" from the angles edge. The rivets I think from memory are on the centreline of the angle. Did you chamfer the internal corners on the splice plates where the plates meet each other?
Steve
Sonex 892
3300 TD 80hrs

Yeah, I literally spent hours chamfering and fitting to make sure everything fit together correctly. :?

Hopefully Kerry will just tell me to not worry, but we'll see. I'm not sure once I open up those holes to 3/16 that there will be anywhere near 3/8 to the edge on mine. I'll look and measure tomorrow morning.

[sonex892]

I'm not sure once I open up those holes to 3/16 that there will be anywhere near 3/8 to the edge on mine.

3/8" from the edge of the angle to the centre of the hole

Steve 892

[Andy Walker]

I'm not sure once I open up those holes to 3/16 that there will be anywhere near 3/8 to the edge on mine.

3/8" from the edge of the angle to the centre of the hole

Steve 892

Yeah, no-go on this. I measure the shortest distance to the center of the hole is 3/16, and none of the four are anywhere near 3/8. More like 2/8. I guess I just was not aggressive enough when chamfering, though it seemed like I removed a lot of metal. Sigh.

[Andy Walker]

Okay, I think I figured out what went wrong. I think when I drilled the pilot holes, instead of being square they were angled upward (I was using a 12" flexible bit and it was hard to get in there with the floor in, I tried to be careful to keep it square, but...).

So if I could find a way to make sure the bit stays square and does not shift, I could updrill from the outside to #21 then 3/16 and take the angle out of the hole, leaving the upper edge of the hole where it is and fill out the hole on the lower side. This would end up with holes about 3/8 center to edge of the longeron.

The only problem is I'm not sure how to do this, and if I hose it up I'll have some *really* ugly holes and probably have to replace the longerons or make some other drastic repair. Any suggestions?

[falvarez]

If you haven't updrilled yet, you may be able to move the center of the hole. I was able to move some holes slightly by drilling a good hole in a piece of scrap 3/16" aluminum, clamping the scrap 3/16" aluminum where I wanted the center of the hole to be (of course you can only move the hole so far), then starting the updrilling process. Taking my time with this approach I've been able to move the center to something more suitable.

Hope this makes sense.

Frank
Sonex #800 - Scratch Building
Middleburg, FL

[Andy Walker]

If you haven't updrilled yet, you may be able to move the center of the hole. I was able to move some holes slightly by drilling a good hole in a piece of scrap 3/16" aluminum, clamping the scrap 3/16" aluminum where I wanted the center of the hole to be (of course you can only move the hole so far), then starting the updrilling process. Taking my time with this approach I've been able to move the center to something more suitable.

Hope this makes sense.

Frank
Sonex #800 - Scratch Building
Middleburg, FL

That's a huge help, Frank. I was just doing some experimenting on some scrap, and figured out I could easily move the hole down using the drill press, but the results doing it by hand are kind of ugly. I was just about to unbolt each side panel and put them on the drill press (unwieldy!)...but now I think I'll try your method on some scrap and see how it works for me before moving forward with taking the whole fuselage apart.

If I can keep the top of each hole and move the centers downward, I think I'll be in business. I love the great ideas I get from other Sonex builders! :D

[Andy Walker]

Okay, I spent the morning pulling the sides off the fuselage (no fun) and put them up on the drill press (wife the wife's help). I was able to push the hole centers down quite a bit, and while they are not quite 3/8 center to edge, they are pretty close:



What do you guys think? Those are drilled out to 3/16, so there's no more room for making changes at this point. If I want better than that, I think my next step would be to re-make the splice plate longer and put a third bolt in.