Michael Burbidge

Michael Burbidge

Well Known Member
Yesterday I mostly riveted the ribs to the main and rear spar of the left wing. When I got to the outboard rib I noticed that the drawings called for flush rivets. I had not dimpled the spar and the doubler plate before assembly. That also brought to my attention the fact that I had not dimpled the flange here either. The double plate has a flange.

The instructions had made a big deal about some of the holes on the inboard double plate needing to be coutner-sunk but said nothing about the outer or middle doubler plate. I guess this is a good lesson in looking at each rivet on a part and thinking about how it will be dimpled and set before assembly.

Is my only alternative to drill out the rivets and dimple the parts separately. The material is too thin to counter-sink. Is there a chance that I can dimple the two parts together?

The middle doubler plate will be challenging to drill out the rivets. In particular, the rivets holding the rib to the flange. With the rivets right next to the rib I'm not sure how I'm going to get a drill in there and keep the hole in the middle and straight.
 
No problem dimpling parts together

As long as you can get enough pressure, there's nothing wrong with dimpling parts together.
 
The plans.....

........get less detailed the further along you go. Examining the plans, looking for all of the notes and comments, making sure the proper size rivets are used and the countersinking is covered also. I have had to study the plans for a couple of hours to make sure that I know what I'm about to do. At first I didn't think it was that necessary to go over the plans that closely but there are things on the plans that are not in the instructions.

God luck!
 
The plans do indeed get scarce with details as you go along, some things are assumed as far as builders knowledge once you get to a certain point.

For instance - you'll get here soon enough, you're not far behind me at all - the main wing spars must be countersunk for the outboard leading edge skin-to-spar rivets (AN426AD3-4s, I believe) and the leading edge skin itself must be dimpled for those rivets. Nowhere in the instructions does it say to dimple the skins for that rivet line, nor does it say to countersink the spar for that rivet line - but the rivet callout for that rivet line is a 426. That's your only indicator that you need to dimple the skin and C/S the spar to accept the dimple. The instructions also will not tell you that you should prime over those countersunk holes before riveting - but you are expected to know that also, just as you did for the tank attach nutplate countersinks on the inboard portion of the spar.

Learn to read ahead and anticipate - there are many, many examples of points like this.
 
dimpling parts together

Mel said:
As long as you can get enough pressure, there's nothing wrong with dimpling parts together.
Click to expand...

In some cases I have found that dimpling two parts together makes a much better dimple than dimlping two pieces separately and then putting them together.
 
Dimpling together can work

I've only had to do it a couple times, but I've had good results dimpling two pieces at the same time. Of course, YMMV, but I'd try it. As stated before, some time you can actually get a better dimple that way.
 
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