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Practice control surface kit: drilling spar

irontrack

Member
So i'm at the point in the van's practice control surface kit where i need to drill the spar. Now the instructions say to just clamp the A-905 R/L ribs to the ends of the spar amd drill out the rib holes with a 12" drill bit (assuming #40 here for the AN426AD3-3.5).

This seems like not the best way to get a good fit on the skins. So i cleco'd the skins to the ribs and clamped the spar in place. What i want to do is use a normal #40 jober bit to drill the spar using the skin as a guide. Is this a good idea/ better than the instruction or am i missing something?
 

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I cant see that being bad, but also not really better. In my kit, the rib fit very snugly inside the spar and therefor I dont think I would have gotten a difference in fit between the two approaches.
 
Drill bit

Wonder why a 12" bit?
Since the holes are prepunched, I would add as many clekos as possible, then clamp, then drill with a matching size bit.
 
So i'm at the point in the van's practice control surface kit where i need to drill the spar. Now the instructions say to just clamp the A-905 R/L ribs to the ends of the spar amd drill out the rib holes with a 12" drill bit (assuming #40 here for the AN426AD3-3.5).

This seems like not the best way to get a good fit on the skins. So i cleco'd the skins to the ribs and clamped the spar in place. What i want to do is use a normal #40 jober bit to drill the spar using the skin as a guide. Is this a good idea/ better than the instruction or am i missing something?

Isn't it telling you to use the 12" bit (#30) to go thru the rib, spar and doubler?
 
Isn't it telling you to use the 12" bit (#30) to go thru the rib, spar and doubler?

Still, a 12"bit seems excessive. there seems to be room for even that part, but I wasn't really trying to line up the part where I need to drill the holes for the doubler. also, I didn't realize the double lines up with the rib for and holes?
 
Oh I think i see it now. I guess it does make sense if this is more about the holes for the doubler and rib where the spar, rib, and double all sandwich together. The step said to reference the a figure which also had the skins and I guess I focused more on that.
 
Oh I think i see it now. I guess it does make sense if this is more about the holes for the doubler and rib where the spar, rib, and double all sandwich together. The step said to reference the a figure which also had the skins and I guess I focused more on that.

I think the skins are on to align the rib to the spar, by the skin being clecoed to the spar and rib
 
Oh I think i see it now. I guess it does make sense if this is more about the holes for the doubler and rib where the spar, rib, and double all sandwich together. The step said to reference the a figure which also had the skins and I guess I focused more on that.

Yes, it's the 2 #30 holes on each side that need this 12" bit. I did one kit with a 12" bit and one with an angle drill bit. The 12" bit did a much better job.

Soon you will get to the point when you dimple the spar and ribs. In the Synergy Air class, we dimpled them together. Better may be to dimple the rib before you do the #30 rivets.
 
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