Rudder Assistance

[CharlieWaffles]

Ok, reached my first point where I need some points I can't find elsewhere. I am finishing the prep for the rudder assembly (7-6) and on step 12: Countersinking the trailing edge (R-1006). I've dimpled the skins (Step 11) with the 3/32 dimplier as usual. I'm using the micro-stop countersinker and have a good handle on its operation. However, when I attempt to create a countersink in R-1006 large enough to hold the skin dimple, I get one of two effects.

1) The countersink is too shallow and a test fit of the skin shows the skin dimple not completely resting in the dimple

2) If I counter sink large enough to fit the skin dimple, the rivet hole in the R1006 is enlarge as the countersinking bit enlarges the hole by intersecting the countersink on the opposite side.

What am I doing wrong? Is the enlarge hole normal? Should I just use a 1/8 countersink instead so I dont get the chatter from the countersink schooting around in the hole as it enlarges?

 

[ChrisC]

What am I doing wrong? Is the enlarge hole normal? Should I just use a 1/8 countersink instead so I dont get the chatter from the countersink schooting around in the hole as it enlarges?

As far as I know, that enlargement is normal. Since the metal you are countersinking doesn't actually hold the rivet in place (the opposite skin does this), I believe it is not harmful to have a wee bit of enlargement here, as long as your countersink is not too deep (aka, the metal should be fully backing the countersunk skin on both sides).

What I did: I got a chisel and carved a triangular groove into a block of wood, the shape of the trailing edge piece. I then put my countersink cutter in my drill press, clamped the trailing edge into this block on the table, and drilled it. This way I avoided any chattering. I'll freely admit that this technique is likely overkill...

Chris

 

[Bob Axsom]

Precision and craftsmanship

...

What I did: I got a chisel and carved a triangular groove into a block of wood, the shape of the trailing edge piece. I then put my countersink cutter in my drill press, clamped the trailing edge into this block on the table, and drilled it. This way I avoided any chattering. I'll freely admit that this technique is likely overkill...

Chris

Oh, but so nice.

Bob Axsom

 

[RV10Man]

Ok, reached my first point where I need some points I can't find elsewhere. I am finishing the prep for the rudder assembly (7-6) and on step 12: Countersinking the trailing edge (R-1006). I've dimpled the skins (Step 11) with the 3/32 dimplier as usual. I'm using the micro-stop countersinker and have a good handle on its operation. However, when I attempt to create a countersink in R-1006 large enough to hold the skin dimple, I get one of two effects.

1) The countersink is too shallow and a test fit of the skin shows the skin dimple not completely resting in the dimple

2) If I counter sink large enough to fit the skin dimple, the rivet hole in the R1006 is enlarge as the countersinking bit enlarges the hole by intersecting the countersink on the opposite side.

What am I doing wrong? Is the enlarge hole normal? Should I just use a 1/8 countersink instead so I dont get the chatter from the countersink schooting around in the hole as it enlarges?

I think your're looking too close at it. Just make it look like an airplane, it'll be ok. Van says your're not building a Swiss watch, it's an airplane.

Marshall Alexander

 

[flion]

I drilled the wedge to a piece of particle board and then countersunk to that (not as nice as routing a piece of wood for a drill press jig, but much quicker and easier). The wood provided pilot holes for the countersink even when the wedge had enlarged slightly. The skins will have the correct hole diameter and depth for the rivets, so the hole enlargement is not a structural issue. One advantage to my method is you can use the wood to jig the TE straight while the proseal sets (assuming you used a straight piece of particle board). I laid the board on my worktable, clecoed the TE to it, and laid a 4x4 board on top against the clecos to hold the TE down flat after gluing. You'll find plenty of riveting tips to help keep it straight during that process in other threads.

 

[Phil]

Mark,

I think that's pretty normal on those trailing edges. I actually removed the cage from the countersink and did it by hand in the drill press using my eye for depth control.

One of the things I did find to help was using a second piece of trailing edge material to insert underneath the material being countersunk. This would square up the material on the drill press table and keep the bit moving perfectly in-line with the holes being counter sunk. (In other words it keeps you from countersinking one side of the hole deeper than the other.)

Here's the best photo I have of it, but trust me there are two pieces of trailing edge wedges there and only the top one is being countersunk.

Phil

 

[CharlieWaffles]

Makes sense, I keep the we're going to Denver, not Mars" in my head most times, but when I started creating a larger hole that I expected, I figured I'd check to make sure I wasnt doing something silly or reading it wrong.

On the subject of rudder questions...

1) On 7-3, where you are splitting the skin stiffners for the rudder. I completed this and then looking back found the numbering weird. In my mind, I know the image of the stiffner is "flattened" out to demonstrate what it looks like. But what I dont get is, is the piece pressed "forward (away from you)" or "back (towards you)"? The reason I ask, look at the illustration of R-1015A-R and -L. In my mind, the flange will be bent towards you, but when you look at 7-5 where you are making the stiffner triangles (Figure 1) the -L piece appears to be bent as I assumed the -R piece is bent. So did I picture the pieces wrong and label them backwards, or is this figure in conflict with the numbering on 7-3? This is concering me due to the final assemly insisting the -L stiffner be above the -R and I'm not sure which stiffner is truly the -L.

2) My flush rivet set from Avery came with a few different diameters, but also thicknesses of the head. There no indication if some of these are for the shop head of any rivet versus the manufactured head of a flut rivet. Does it matter which "thickness" is used on which side of a rivet or just as long as it does the job?

 

[Mike S]

I also used a second piece of wedge to level out the one I was working on.

Carry forth

 

[ChrisC]

2) My flush rivet set from Avery came with a few different diameters, but also thicknesses of the head. There no indication if some of these are for the shop head of any rivet versus the manufactured head of a flut rivet. Does it matter which "thickness" is used on which side of a rivet or just as long as it does the job?

Different thicknesses are useful in different places. In some spots you need a thicker set to reach around some other bit which is in the way. In other places a thinner set lets you squeeze into a spot which otherwise you wouldn't be able to fit into.

I'm pretty sure a flat set is a flat set, and they don't know the difference between the shop and manufactured head of a flush rivet. (Of course, for universal rivets the manufactured head is a different shape...)

Chris