Ribs to spars?

I am now clecoing my ribs to the spars for match drilling. I'm wondering if I should also match drill the holes in the top and bottom tabs of the ribs? (see pic)



If I match drill these now, they won't be match drilled together with the skins. But the ribs are suppose the be riveted to the spar now. So if I rivet the ribs to the spar, I won't be able to debur the holes in the tabs once I match drill them with the skins.

So I'm assuming I need to drill these now, and then debur them when I take the ribs back off to debur all the holes. Then, later when I put on the skins, I'll have to drill out the skins but the spar and rib will already be final size.

Does any of that make sense?

The matched holes line up pretty well. all you should be doing here is clearing the hole in the spar anyway, not elongating it any. The skin should go on fine.

For what it`s worth, I`ve assembled my entire wing into a frame and match drilled it all together just to avoid any misfit issues like you are asking about should any come up and bite me. The only issue I had was with the way the manual says to drill the tank brackets.
If you haven`t drilled the fuel tank attach brackets yet, there`s better ways than how the manual says to do it.

Holy **** Mark, I looked at the pictures of your Rans. Good thoughts on keeping a fire extingusher in your plane. We have them in our cars too.

The picture you used to ask the drilling question could have been from my garage. I am working on the same thing. I clecoed the structure together and drilled the rib-spar connections. Next I took everything apart and deburred the ribs, installed the platenuts. It was much easier for me to squeeze the platenuts on with the spar laying flat on my stand. I could see both sides of the rivet and it went pretty quick that way.

I don't see a problem reaming the holes out at the stage you are at. If you use a reaming bit, there is very little or no deburring to do on the holes. It makes a very clean hole.

Makes total sense...

Mark,
I read your post again and now I understand. You're just fine.

Dont worry about match drilling at this point. Once you get the ends of the ribs riveted to the spars, and the wing mounted on a stand you will fit the skins. Even if you've only done a "OK" job on fluting, the ribs will line up pretty well. Regardless, the ribs will easily flex to allow all the holes to line up with the skin. After you get the skin mounted, you'll match drill all the holes in the skin, rib and appropriate spar holes. (don't forget your doubler...I warned you)

Hope this helps.

Gil - if I wait to drill these holes out to #40 until the skins, won't I have to debur the holes in the spar and rib? I won't be able to do that because the ribs would be riveted to the spar.

Maybe I should not have said 'match drill'. I think I confused everyone when I used that term. The real quastion is should I open these holes up to #40?

Let me re-phrase my question...Should I drill out the holes (marked with the red arrows) to #40 before I rivet the ribs to the spars?

(just went to a chapter meeting tonight and looked at an RV-9A in the hangar-holy **** I have a long way to go!!)

s10sakota said:

Should I drill out the holes (marked with the red arrows) to #40 before I rivet the ribs to the spars?

Click to expand...

I did that and then deburred them both sides before rivetting the ribs on.
You'll see that that the skin fits just fine afterwards and you can matchdrill the skin afterwards. To be sure you don't elongate the original holes , you can backdrill through the skin using the spar as the drill guide using the ange drill.
You'll be revisiting these holes again as you also need to countersink them later.

The only disadvantage if you don't do this now is that you will not be able to deburr what is between spar flange and rib tab.
But then again, I'll answer with the most heared standard Vans response to this kind of questions: 'you're building a tractor, not a space shuttle, build on'

Have fun.

Ok, that all makes sense...moving on...

JurgenRoeland said:

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The only disadvantage if you don't do this now is that you will not be able to deburr what is between spar flange and rib tab.
But then again, I'll answer with the most heared standard Vans response to this kind of questions: 'you're building a tractor, not a space shuttle, build on'

Have fun.

Click to expand...

It's been my experience that when you drill or ream tightly fitted parts, as these are, the adjoining surfaces need practically no deburring anyway.

I match drilled them also at this stage..

I had the same questions about drilling them now or later with the skins. I did it prior to riveting on the ribs so I could deburr each part un-assembled.

When you go to rivet on the rear spar, you will have the same question about the lower most aft pilot hole in each main rib flange as they nest together. I drilled and dimpled both the rear spar hole and the rib hole before riveting. The squeezer may be able to dimple both parts together.