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  #1  
Old 01-11-2013, 08:52 PM
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N546RV N546RV is offline
 
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Default I made a stupid tonight with E-606PP

Semi-obligatory self-reflective intro: Is it just me, or do these moments always seem to come at the same sort of time? You're out in the shop, you get in a good groove, you're all pleased with your productivity...you might even, at some point, think to yourself, "I'd better be careful, or I'll get carried away and make a mistake..."



Anyway, last night I match-drilled all the left elevator parts, and tonight I set about deburring and dimpling everything. I hit up all the usual stuff: spar, ribs, counterweight skin, etc. That list included my new best friend, E-606PP, on which I proceeded to intrepidly dimple both flanges.

That done, I was about ready to call it a night and head, inside, but I decided to read ahead in the instructions a bit. Well, what do you know...just a couple lines down it specifically addresses E-606PP, along the lines of "Machine countersink the top flange and dimple the bottom flange."

Internal head voice: "Countersink? Just the top? But why...ohhhhhh...the hinge for the trim tab goes there, and needs a flush surface to rest on."

*sigh*

I started to bust out the rivet gun, flush set, and back rivet plate to flatten out all those nice dimples I'd just made, but then realize I was getting right back into the mindset that caused the screw-up in the first place...too much working, not enough thinking.

Then I had another thought: Maybe I could just countersink the hinge piece itself and not have to go flatten all those dimples. Might make drilling the hinge in place a little more challenging, but at least I wouldn't risk messing up a bunch of previously good holes and having to reorder a part.

So, I submit the question to the peanut gallery: Which should I do? Flatten the dimples, countersink E-606PP, hope the holes don't get buggered? Or leave the dimples there and plan on countersinking the hinge?

I'm leaning towards countersinking the hinge, but I want to make sure I'm not overlooking some kind of problem that might result.

Thanks!
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  #2  
Old 01-11-2013, 09:06 PM
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KMinor KMinor is offline
 
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Default

I think the consensus you will hear is flatten the dimples with a squeezer and flush sets, then countersink the spar.
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  #3  
Old 01-11-2013, 09:24 PM
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Yeah flatten it back out and go from there, I would not attempt to countersink The hinge. Flattening out the metal one time should not cause any problems.

Bird
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  #4  
Old 01-11-2013, 09:34 PM
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N546RV N546RV is offline
 
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Yeah, suddenly it occurs to me that (I think) there'd be a problem trying to countersink the hinge. Wouldn't the hinge itself (ie the part that holds the hinge pin, not sure of there's an "official" term for that) get in the way of the countersink cage?

I'd go out to the garage and check, but I'm all comfy in bed now. Getting dressed again would be far too much work.
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  #5  
Old 01-11-2013, 09:46 PM
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RV7AJeremy RV7AJeremy is offline
 
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Default Emphasize squeezer

Quote:
Originally Posted by KMinor View Post
I think the consensus you will hear is flatten the dimples with a squeezer and flush sets, then countersink the spar.
Use your squeezer, and NOT your rivet gun, the gun will pancake and miss shape your material.

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  #6  
Old 01-12-2013, 01:03 AM
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Andy Hill Andy Hill is offline
 
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Personally I'd not rush to "undimple" the spar. The spar is the key structual item here. You are not only reducing strength by "undimpling" (to a small degree), but then C/S into that area.

The hinge is easily C/S - even if you cannot get the cage on it, just use the deburring tool, ideally with the C/S tool part in it. NB whilst the hinge will be slightly weaker due C/S, I am sure I have C/S hinge in various locations, and a C/S joint is stronger is some ways than flat.

I am not pushing you one way or the other - but as you hint, take the time to the best (which might include easiest) solution from where you are now, not rush back to try and get back to where the plans say you should have been
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  #7  
Old 01-12-2013, 01:39 AM
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az_gila az_gila is offline
 
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Smile Back up strip

Quote:
Originally Posted by Andy Hill View Post
Personally I'd not rush to "undimple" the spar. The spar is the key structual item here. You are not only reducing strength by "undimpling" (to a small degree), but then C/S into that area.

The hinge is easily C/S - even if you cannot get the cage on it, just use the deburring tool, ideally with the C/S tool part in it. NB whilst the hinge will be slightly weaker due C/S, I am sure I have C/S hinge in various locations, and a C/S joint is stronger is some ways than flat.

I am not pushing you one way or the other - but as you hint, take the time to the best (which might include easiest) solution from where you are now, not rush back to try and get back to where the plans say you should have been
LIke Andy says, at this stage I think I would c/s the hinge. You can get a cage on it since the ears of the hinge will be on the other side of the surface you c/s.

If you do this I would also add a back up strip of alum. on the bottom. The hinge material is pretty soft and you would not want the shop head of the rivets to be against the thinner parts of the hinge that have been countersunk away.

This backup strip will sandwich the hinge in and prevent any possible rivet tear out under load.
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Last edited by az_gila : 01-12-2013 at 01:42 AM.
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  #8  
Old 01-12-2013, 04:28 AM
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derLuigi derLuigi is offline
 
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Philip,
you can simply dimple the hinge (that has been done often, it's been discussed a couple of times in other threads).
I wouldn't do that (anymore) on the flap hinge because mine stretched very slightly during dimpling, on the short trim-tab hinge that's not an issue though.
As far as I remember Van's recommended dimpling the hinge as well an said not to countersink it.
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  #9  
Old 01-12-2013, 05:10 AM
hayabusa hayabusa is offline
 
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I dimpled these parts on my 7. No problems dimpling the hinge material with a hand squeezer. It all works out fine.
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  #10  
Old 01-12-2013, 09:11 AM
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Default

I would just dimple the hinge or flatten the spar. I don't like to C/S thin material especially when the hinge will interfere with the cage.
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