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FlyerJumper

Well Known Member
I was getting ready to rivet on the vertical stabilizer skin, and also rivet the trailing edge of our rudder the other day, when to my surprise the 3/32" clecos wouldn't grab hold. Tried it in numerous holes... same result. Long story short, I used a little too much umph on the dimpling, and wound up oversizing all the holes in the skins, ribs and spars. MIL-R-47196 says hole size for 3/32" rivets should be between .093"-.103". Took the digital calipers to mine and they're all .105"-.110" :eek: . Even though the holes in the rudder skins are also oversized, I didn't notice a problem riveting the rudder skins to the stiffeners and spars because my wife dimpled the holes in the stiffeners & spars (the holes she did checked out perfect -- I've already set up a time for her to give me a class on how to dimple ;) ).

What's the general consensus on my options?
 
I have not measured mine but I had trouble with my Cleko brand clecos popping out once the holes were dimpled. I bought some Wedgelock brand clecos from Cleaveland Tool and have had no problem since.

I'm not sure how you could over dimple. The dies are meant to come together and I don't see how they would enlarge a correct size hole. :confused:

I'm sure others will be able to answer the size question better.
 
Holes...

FlyerJumper,

The dimpling process does enlarge the holes slightly - it stretches the metal.

Sometimes a saller #41 drill instead of a #40 for the initial hole helps.

The dimpled holes edges are "angled" on the inside surface, and this does seem to make some of the cheaper brands of clecos loose their grip... I had the same problem, and sometimes selected clecos out of my bucket by brand. Easy to do since my good ones were slightly shorter.... :)

Going to a rivet length that is a 1/2 size longer will help you fill the slightly larger hole, and still end up with a good sized shop head, giving you more tolerance in rivet gun "burb" time...

gil in Tucson
 
I have both the Wedgelok and Cleco brands. Cant use the Cleco brand on dimpled holes. I can easily tell the difference. The Cleco brand top is a much brighter silver color while the Wedgelok is a darker gray. I keep them in separate buckets.

Charlie
N464CB 8A (subie)
Fuselage
 
Yeah, and now we need a count of who is selling which brand... I.E. which sellers to avoid :).
 
Oversize holes

Mark,

Bob Avery spent quite a lot of his time going over this very subject with me. I had the same problem while doing the practice kit. His advice was to be very careful with the deburring process. If one uses a deburring bit such as the one on the Avery deburring tool, it will form a shoulder that is (if my math is correct) at a 40 degree angle to the top of the surface one is deburring. Then when the dimpler is used it bends the metal around the hole down another 40 degrees. So now your deburr shoulder is suddenly at an 80 degree angle with the surface, and becomes basically the inside diameter of the hole. Essentially, everything one removes in the deburring process comes off the inside of a dimpled hole. At least that is what I got from the conversation with Bob. His recommendation was to try a #41 bit and be careful with the deburring tool. I realize this doesn't answer your question of what do you do now, but I hope it will help in the future. By the way, I sent my Clekolock brand clecos back and got some Wedgelocks also.

James Jennings
RV9 Empennage N94JJ
 
FWIW, aircraft spruce's don't hold... they are called kwik-lock or something...

I guess I'll need to pick up a hundred or so Wedgelocks too...
 
Mark,

James is absolutely correct. I have a link here to a drawing that we use for reference on this topic. Over-deburring is really a problem for dimpled holes. We recommend putting on some gloves and knocking off any chips or burrs by hand rather than running something in the hole. Deburring is way over-emphasized. If a deburr tool must be used it should be used very lightly so it does not cut away any of the metal -- only the burr. We use USA made Zephyr clecos and do not usually have this problem, except when parts are over-deburred and dimpled.

Glenna
www.planetools.com :) http://www.planetools.com/BuildersHelp.html
 
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