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Dimpling the rudder ribs

M5fly

Well Known Member
I'm dimpling the ribs for the rudder but am stuck on what to do with the 3 holes closest to the trailing edge on both the top and bottom rib. Do you just use pop rivets there instead? I imagine bucking would also be an issue even if I manage to get them dimpled. Plans just show flush rivets here.
 

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I dimpled those by making a thin female die from a 3/16" or so mild steel bar using a countersink cutter to make the recess in the bar. I can't remember what I used for the male die, might've been just a rivet tapped into the recess to make the dimple. Final rivets are all solid.
 
Vice grip tool

I used the Cleveland Vice Grip dimple tool. Also used a MK-319-BS in the last two holes.
 
Thanks for all the replies, I'll see if I can find someone locally who has one of these options to borrow. Did you guys also use a really thin piece of steel to buck the last couple rivets?
 
Home made bucking bar

Thanks for all the replies, I'll see if I can find someone locally who has one of these options to borrow. Did you guys also use a really thin piece of steel to buck the last couple rivets?

If you really want to set rivets...
Grab the tungsten and a really hard, thin piece of steel. A big flat screwdriver wlll work.
Tale the tungsten as close to the work as possible. The idea is to add mass.
I tape my tungsten to all sorts of home made bars. Works great.
 
There are many dimplers on the market for just such a task. Cleveland has both the pliers (which I use the most), a female die at the end of a flat rod, which I tried and didn’t love, and the pop-rivet dimpler shown above.

There are also bucking bars shaped to fit this space as well.

Good luck.
 
This is the right elevator on my 7 but same principal.

I drilled and countersunk (made a female dimple die) a piece of steel that would fit, put it in a vice, positioned the elevator and tapped my male dimple die with a hammer to dimple.

Here's one way to rivet using a back-riveting plate and a steel wedge on the shop side. "Rivet" the wedge.
 

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Like Paul, I made a female dimple die by countersinking a piece of 3/16 steel plate, which fits inside the narrow end of the rib. For the male die I've just used a rivet and gunned it with a mushroom set, but the dimple was not great. I get better results with an actual male dimple die in a rivet gun adapter shank, but there's a risk of snapping the nose off of the die if you don't hold it quite square.

For the riveting, there's a "transfer bar" way of back-riveting, using a bit of steel as a class 3 lever (mine's another bit of 3/16 about 1x3, with one end thinned for clearance). With the work piece face-down on the back rivet plate, one end of the transfer bar sits on the rivet tail, the other end rests on the plate, and the rivet gun smacks the middle of the bar. Bit of a pain...it needs more air, the bar likes to walk away, and you have to be careful about marring the rib web with the end of the bar. But it works.

(Edit: EAA has videos on this, tight quarter dimpling and riveting)

Or...yeah, MK-319-BS pulled rivets. I've done that too. Verify it with Vans for your application, but they gave me a blanket approval for substituting a 426-3 where the grip length is adequate.
 
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Love the tips, hadn't thought of the screwdriver idea for bucking. I opted for having the sheet metal guys at work countersink a piece of scrap steel to make the female die. Seems to work well enough to dimple the 14 holes I need to. I'll definitely try a couple of the bucking methods mentioned and see what works best for me. It's amazing the amount of special tools you need just for one small project!
 
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