trailing edge wedge

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Joe Parish
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trailing edge wedge

Post by Joe Parish »

Tonight I countersunk the trailing edge wedge for the rudder. Once I went to the second side the holes of course open up some but I have some that got elongated. I was using my air drill with micro stop. I am wondering if this will be an issue? If I should order a new wedge or move on. In the holes on the wedge you end up with a knife edge due to countersinking both sides. The cutter is a single flute. Not sure how to prevent this from happening?
Joe
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captain_john
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Post by captain_john »

Joe, can you go up one size rivet?

Sometimes fattening one up by pre-squeezing a longer than normal one works well too.

:) CJ
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retasker
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trailing edge wedge

Post by retasker »

The only way to prevent this is to use something like a drill press with
a fixture to hold the wedge so neither it or the microstop can move
relative to each other or use a backing plate. You will run into this
same issue on other locations where there is nothing to prevent the
microstop from moving. What you do is use a backing piece with an
appropriate sized hole in it that is held in place with a clamp or cleco
to hold the center pin of the countersink in position so that the that
the countersink cannot chatter or move and elongate the hole. This is
especially important when doing the countersinks on the spar to hold the
fuel tank on - make a note for the future! Replacing a wedge if
necessary is not a big deal. Doing the same for the wing spar is a much
bigger deal...

That said, in this situation, as long as the holes aren't wildly
oversized, it is not a disaster since the wedge is really only acting as
a spacer to keep the two pieces of sheet aluminum at the right angle to
each other. As you noted, the wedge really does not have the rivets
touching it. The two skins with the dimpled holes are essentially
touching, so as long as you haven't elongated all the holes a bunch, I
wouldn't worry about it.

You are using a countersink with the center pin to keep it centered in
the hole, correct?

Dick Tasker

RB Lists - RV9 wrote:
>
> Tonight I countersunk the trailing edge wedge for the rudder. Once I
> went to the second side the holes of course open up some but I have
> some that got elongated. I was using my air drill with micro stop. I
> am wondering if this will be an issue? If I should order a new wedge
> or move on. In the holes on the wedge you end up with a knife edge due
> to countersinking both sides. The cutter is a single flute. Not sure
> how to prevent this from happening?
>
>
> ------------------------------------------------------------------------
>
> Joe
> N525XC reserved
> Empennage in progress
> wings ordered
> RV-9
>
>
> rivetbangers.com - Discussion topic
> http://www.rivetbangers.com/forums/view ... 6136#36136
>

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Joe Parish
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Joined: Wed Apr 21, 2010 3:42 pm
Location: Sioux Falls SD

trailing edge wedge

Post by Joe Parish »

I may try that John. I set my jig in my drill press and finished it up. That kept me from elongating any other holes. The ones that are not elongated seem to run from .115 to .120 in size? One of the elongated ones is at @ .130 thousandths. I did use a slighty longer rivet on one of my practice projects to see how it filled up the dimple(double flush) and I thought it looked better than the ones the plans said to use. I believe it called for a 426 3-3 and I used a 426 3-3.5 I am curious if any one else had issues with it?
Joe
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Empennage done
wings done
Fuse in progress
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cjensen
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Post by cjensen »

The hole size in the wedge doesn't matter...you're riveting the two skins together and the holes in the skins will be properly sized. The wedge is just there to make the two skins stay in the V shape. The wedge also gets installed with sealant, so don't worry about the hole size after c-sinking each side. It ain't goin anywhere... :)
Chad Jensen
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Spike
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Post by Spike »

2 things come to mine.
  • Always always always use something to back the counter sink if the pilot hole is not deep enough to always capture the countersink pilot. I ruined parts until I got militant about this.
  • The second thing is that by definition you will have elongation in the rudder/elevator wedges. This is because the wedge is not thick enough to keep you from enlarging the hole. Because the holes are not in the same plane, because its a wedge, the angles at which the countersinks are cut will force the holes to overlap in a way that causes elongation. The only way to prevent it would be to cut those countersinks perpendicular to the centerline of the part and not perpendicular to the face. And that is not what you want to do.
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bruceh
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Post by bruceh »

I did the countersinking for the wedge with the microstop on the drill press. To keep the top surface of the wedge perpendicular to the countersink bit, just use a small section of wedge material underneath in the opposite orientation. I just taped it down with masking tape. Predrill a #40 hole in it to keep the countersink bit centered. The holes will be elongated, but that is more due to the limited thickness of the wedge and no one will ever see this once it is prosealed and riveted under the skins.
Bruce Hill
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