J

John Courte

Well Known Member
Sorry, can't remember the number of the part, but it's the big rib
that attaches to the lower end of the rudder spar.

Last night, I dimpled this part, with a squeezer, and now it's got
a nice, smooth warp to it. As in, if you lay it on the bench
flanges pointing up, the whole thing is bowed upward from ends to middle.
Dimpling warped the rib. This rib is made of the same material
as the spar. Was I supposed to dimple this thing while it's
clecoed to the skin? Furthermore, is it OK/recommended/advisable
to flute this part back into a straight line? Dimpling the spar itself
was OK, no problems there, and the upper ribs, the ones made of thinner
material, no problems there either.

Other than that, it's all going swimmingly. Since I received the empennage
kit, it's been 5 months, my website's gone down twice, but I've completed
the HS and VS, minus the fiberglass tips. Clearly, I'm in no hurry, but I'm
anxious to be done with the empennage. ;)
 
R-904

I believe your are talking about the R-904 rib. I dimpled mine and had no problems. I did not need to flute it. Silly question but did you drill and dimple to #30 or #40? It is also possible that it was squeezed to hard. I have run into this when using my pnumatic squeezer. Oh well, just some thoughts for ya...

Mike R.
Fuselage
 
Actually, it almost sounds like it wasn't dimpled hard enough. If you don't dimple hard enough, instead of a nice crisp dimple, you'll bend the flange just a bit. Next time you dimple, run the squeezer up slowly and you'll see the flange slowy deform a little, and then as the last little bit squeezes it'll all come back into shape. I had a similar problem early on that deformed one of my flanges just a touch, but not so much that the part bowed significantly, and redimpling fixed it right up.

I dunno...it's worth a look if all else fails :)
 
I drilled and dimpled to #40. And the squeezer was full on. Either that or
I had a #40 male die and a #30 female die, which would make me the
most inept dork on the planet. The only other thing
I can think of is that the adjustable piston was too far extended and there
was some play in the yoke that would let the dies wobble. But it's still
weird. I dimpled the rest of the parts with the same setup and didn't
have a problem.

I'll try to re-dimple it, but I don't think that's going to help. I know for a
fact that I can flute it back into line. The question is, should I?
 
John Courte said:
I drilled and dimpled to #40. And the squeezer was full on. Either that or
I had a #40 male die and a #30 female die, which would make me the
most inept dork on the planet. The only other thing
I can think of is that the adjustable piston was too far extended and there
was some play in the yoke that would let the dies wobble. But it's still
weird. I dimpled the rest of the parts with the same setup and didn't
have a problem.

I'll try to re-dimple it, but I don't think that's going to help. I know for a
fact that I can flute it back into line. The question is, should I?
Click to expand...

If the dimples look good, I wouldn't redimple. You should probably ask Vans for their suggestion. I don't think it really matters much either way, but you'll sleep better at night when they tell you "If the holes line up, rivet it and move on...if you feel like it, flute it until you're satisfied that it's straight enough". LOL...that's pretty much their mantra unless you've cut a piece in half with a bandsaw, mashed it with a hammer and soaked it in battery acid.
 
Thanks for the advice. I'm going to check the dimples. Then I'm going to flute
it while I'm waiting for a reply from Van's. If they tell me to move on, that's wonderful.
If I have to replace the R-904 rib, so be it.

In the meantime I can csink the trailing edge. Can't wait to get into that tube
of Pro-seal.
 
I think it may have been oversqueezed. when the pressure is up and the squeezer is working properly, it's pretty intense. Would not surprise me if this is what happened, since the bow is away from the edge of the flange. but it's fluted now, and everything's still fine, and Van's said go ahead with it anyhow. Thanks for all the replies.
 
If you have an adjustable set holder, just turn the holder out so the dies just meet when the trigger is pulled. I always ran the screw down, pulled the trigger, the ran the screw out till the dies just touched. That worked well for me when dimpling.

Roberta
 
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