Dimpling in tight places

[Bryan Cotton]

On my mini rudder, the skin rivets were lined up with the bottom rivets and it looked like I would have an interference when I went to pull the rivets. I decided to use flush AN rivets on the one row of the drive horn. 3 of those rivets went through a forward rib that would need to be dimpled, but the holes were way too close to the radius to get a dimple die. I used a 100 degree pop rivet dimpler half and a #6 screw. It came out slightly over dimpled but good. Maybe using a rivet as the male die would have worked. I used a flush set against the screw head and nothing but the female dimple die on the other side.

[Bryan Cotton]

Here is an update on this technique for super tight places. I took a stainless 3/32" flush pop and removed the mandrel. I countersunk a piece of 3/16 scrap. On the C clamp I taped a couple washers to it in cas the rivet stuck out. A thicker piece of scrap would probably be better.


Then you squash it in with the C clamp.


On these dimples I recommend doing them BEFORE you rivet the parts together. Whoops!

[gammaxy]

That seems kindof clever. Are you talking about countersinking the holes for the aluminum rivets on the "wings" of the nutplates? I used my deburring tool to remove just enough material from those holes so the rivets were flush.

[Bryan Cotton]

Whoops, I posted the wrong second picture. It is fixed now. I dimpled rather than countersunk because .025 is too thin to properly countersink, not that it can't be done. Material that is at least .032" is ok to countersink for 3/32" flush rivets. I am going to put a little .032 countersunk shim between the channel and nutplate.

[Bryan Cotton]

Here is another technique, as I forgot the first one and did something new. Countersink a piece of scrap for a 3/32" flush rivet. Then screw a #4 flush screw through the piece and into the countersink.

Edit: here it is in action. Not perfect as it oversizes the hole a bit but workable. Better for solid rivets than pops.

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