Harley_Pilot
Member
Having just ordered the empennage kit for a -14A while at AirVenture, I thought I would do a bit of practice on the Van?s tool box kit. The instructions direct me to match drill (#40) the end pieces and sides then to dimple BOTH with 3/32? dimple die. Rivet together using AN426AD3-3.5 flush rivets. I followed the instructions and worked carefully but the end results were not as nice as I expected.
My rivets are flush, no smiley-faces or dents in the sheet metal, the shop heads are all straight and they?re sized properly. But . . . the rivet heads don?t fit the dimple. There is a ?ring? around the head. I dimpled more holes using my c-frame but every one I tried resulted in the same issue. After some thought, it stands to reason there is a ring because the dimpled hole has a radius. I did more testing and realized a couple more things. When I match drilled the holes with the #40 then dimpled, the hole got bigger. While the rivet wouldn?t fit in the factory punched hole prior to drilling, it did if I skipped the drilling and simply dimpled the piece. When I compared the non-drilled with the drilled holes after dimpling, the ones I drilled are significantly larger. The rivets are pretty loose when I check them for fit prior to riveting.
Third, when I check the fit of the dimpled skin and rib (end and sides on the toolbox), they don?t nest perfectly. It seems to me if I dimple each with the same size dimple I will have gaps in the joints. The only way I can see to fix this problem is to use ever greater size dies on each piece below the top one. So my questions are, should I use one dimple die size for each layer or different size for each piece? Should I skip drilling them if the rivet will fit without drilling after it?s been dimpled? Is the ?ring? around the rivet head just something I?m having to live with? And finally, am I looking for perfection where it?s not possible?
My rivets are flush, no smiley-faces or dents in the sheet metal, the shop heads are all straight and they?re sized properly. But . . . the rivet heads don?t fit the dimple. There is a ?ring? around the head. I dimpled more holes using my c-frame but every one I tried resulted in the same issue. After some thought, it stands to reason there is a ring because the dimpled hole has a radius. I did more testing and realized a couple more things. When I match drilled the holes with the #40 then dimpled, the hole got bigger. While the rivet wouldn?t fit in the factory punched hole prior to drilling, it did if I skipped the drilling and simply dimpled the piece. When I compared the non-drilled with the drilled holes after dimpling, the ones I drilled are significantly larger. The rivets are pretty loose when I check them for fit prior to riveting.
Third, when I check the fit of the dimpled skin and rib (end and sides on the toolbox), they don?t nest perfectly. It seems to me if I dimple each with the same size dimple I will have gaps in the joints. The only way I can see to fix this problem is to use ever greater size dies on each piece below the top one. So my questions are, should I use one dimple die size for each layer or different size for each piece? Should I skip drilling them if the rivet will fit without drilling after it?s been dimpled? Is the ?ring? around the rivet head just something I?m having to live with? And finally, am I looking for perfection where it?s not possible?