All -
I'm ready to prepare the tank skin - to baffle joint.
Van's directions say to countersink the spanwise row of rivets.. but I'm concerned about the thickness of the skin.
I've also read posts where builders have dimpled the row and not had any problem assembling or sealing their tanks.
Some builders have dimpled this skin by mistake. It is thin enough to warrant a dimple, but from what I am told... it is easier to install the baffle with countersinks instead.
The guys who have dimpled it, say no problems... ny and large. Me... I followed the plans and had no problems.
CS it and make life easier on yourself.
CJ
RV-7
Garmin G3X with VP-X & a TMX-IO-360 with G3i
It's all over but the flying! 800+ hours in only 3 years!
I think the spec says that you can CS anything that is a minimum of .032" I used to have problems swallowing that but have since learned that it really is feasible to do a nice job on something that thing. Go for it.
http://www.rivetbangers.com - Now integrating web and mail!
Current Build: 2 years into a beautiful little girl
The problem comes when the rivet sits so deeply that the shoulder of the 100 degree head comes to rest on the flush surface of the underlying material.
This causes a stress riser and a "bad thing" for lackuva bettah wherd.
Rule O' Thumb... Dimple stuff less than .040 and CS stuff .040 and larger. Write it on your wall. Wicked Stick did and that's where I learned it from!
Pass it around...
CJ
RV-7
Garmin G3X with VP-X & a TMX-IO-360 with G3i
It's all over but the flying! 800+ hours in only 3 years!
You can dimple .040 and I think that's the cut-off for thickness.
In my 8's plans it mentions that you can dimple the rear spar channel on the wings where it is .040 and then clean it up a bit with a derbur tool to have the rivet or dimpled skin sit nice and flush.
There are other areas of .040 that get dimpled as well in my project.
There are also other areas of .040 that DO NOT get dimpled like the tank baffle and a rear spar piece on the Elevator where the trim tab mounts.
I think a friend of mine tried to dimple his tank baffle and it didn't work well for some reason, so he ordered a new baffle and skin and countersunk the skin per plans on the 2nd try. I forget why it didn't work out, but I'd follow the plans more if it does call out for it to do so.
Also, very important, when countersinking the tank skins... Keep the baffle clecoed in place so that the countersink bit stays put inside the baffles hole. Otherwise, if you just try to countersink the skin by itself you'll ruin it because it will wander since it's too thin.
The reason for countersinking the tank skin rather than dimpling it is that if you dimple, the rivet tail extends farther through the baffle and may hit the spar reinforcment bars, thus not allowing the tank to seat properly on the wing. Countersinking avoids this problem.
CJ
CJ
