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  #21  
Old 02-03-2017, 11:42 AM
BillL BillL is online now
 
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Location: Central IL
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Quote:
Originally Posted by goldbar View Post
Bill this is feeling a bit like magic to get the fit correct when each time parts are removed and put back causes a fit change. When you made these bushings, were you correcting the 771 and 702 "level" and did you just take the difference and make that the offset?
My frame and plexi fasteners were all complete sans glassing the front. No struts. It fit "perfect" - meaning all the gaps and offset (I call stagger) were even, small or in the case of stagger none. Every rivet hole was dimpled and had clecos, The side rails had cleo clamps and 4-40 screws to hold them in tight. Then, I riveted the 771 on. No so good.

So - my right side raised the frame .010, the left set it back by .020. They don't need to be only X or Y. Any combination works too, according to the need. I still have a scoop on the left side, that also appeared after riveting. Don't know how to handle that yet. So - ensuring that the sub panel curvature remains fixed during the whole process, including final riveting, needs some definitive action. Its a definite risk and all the adjustment options are frozen, except for these bushings. This is why I said one should consider doing the canopy frame after the front skin is riveted. A no win option IMO. Maybe some .063 reinforcement under the curve on the sub panel could maintain the curvature. Purely a guess.
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Last edited by BillL : 02-03-2017 at 11:52 AM.
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  #22  
Old 02-03-2017, 01:27 PM
rv7charlie rv7charlie is offline
 
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If the offset issue really is due to driving the tabs down while riveting, there's at least some chance you can move them back out. I can try to describe the technique, but first, look at the skin to see if there's any distortion around the rivet lines. If the tabs got bent down, you should see visible distortion around the rivets along that rivet line.

Charlie
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  #23  
Old 02-04-2017, 06:10 PM
Smilin' Jack Smilin' Jack is offline
 
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Do a search and find the canopy stops. Once I installed these the skins stopped moving. It is an easy mod...

Smilin' Jack
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  #24  
Old 02-04-2017, 06:52 PM
BillL BillL is online now
 
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Default More please . .

Quote:
Originally Posted by rv7charlie View Post
If the offset issue really is due to driving the tabs down while riveting, there's at least some chance you can move them back out. I can try to describe the technique, but first, look at the skin to see if there's any distortion around the rivet lines. If the tabs got bent down, you should see visible distortion around the rivets along that rivet line.

Charlie
OK, this is my last issue and not sure it can be undone without deriveting the 771 skin, It is not buckled as I can tell and without stretching the 771 or remaining a custom one, not sure how to effect this change. the hing point is on, where it meets the fuse is on. It is like the radius is just reduced by .030 in the middle.

So, if you have done this with success, please elaborate.
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  #25  
Old 02-05-2017, 07:58 PM
rv7charlie rv7charlie is offline
 
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Bill,

If you can lay a flexible ruler along the rivet line & not see any dips, it's likely that the skin just wasn't pulled down tight when you set up your relative heights of the skin & canopy skin. That might make it tough to compensate now, since the sking would be where it's supposed to be.

Having said that...Here's the general technique I was taught to move a 'depressed' bulkhead tab out so there's no dip in the skin over that tab's rivet(s).

I use a hardwood (maple worked for me) 'punch' that's ~3/4" on a side by 5-6" long. I taper one end into an offset cone so the point is near one side. Blunt the cone's point to ~1/2" dia, and drill a hole in the end slightly larger than the shop head of the rivets you're going to work around. Make a similar tool with a wedge, like a very blunt chisel with rounded corners. Grab a hammer or mallet with a decent mass; something about the weight of a standard carpenter's hammer works for me.

Get inside the fuselage, & have a helper ready outside, with a bucking bar with a relatively large flat area, or another piece of hardwood.

Carefully coordinate where the low spots are with your helper. Have the helper place his 'tool' over an offending rivet/tab location, tangent to the skin over the rivet itself. Center the cone'd tool over the shop head, & bump it *gently* with the hammer. Only do this with resistance on the skin over the rivet. Check to see if/how much you've moved it out, and repeat if needed. Check after every bump.

To move the entire tab, use the 'chisel' tool. Hold the 'blade' parallel to the bulkhead, and work a line on the tab between the bulkhead and the rivet line. Idea is to shift the tab's bend radius closer to the rivet. The bulkhead will move a microscopic amount toward the rivet, but it will get noticeably longer, moving the tab 'out'.

That's my story, and I'm sticking to it. Might not do you any good at all, but if you think your tabs got bent down while riveting, it *might* help.

Hope it's of some use,

Charlie
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  #26  
Old 02-05-2017, 09:04 PM
BillL BillL is online now
 
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Default ahhh hammer and dolly

I was just thinking that today. A shaped internal forming tool. There is one tab that is depressed, Maybe a port-a-power, but where to put the other end??

When fitted the skin was pulled down with ratchet straps, big ones, it was very tight. When the skin was put on, it just went on too easy to what I was expecting. Maybe a custom skin will have to be fitted. I am determined it will get done right.

Edit: I have now made an anvil tool with an 8" radius, polished, and radiuses edges. It is welded to an old air hammer tool that will fit nicely in the rivet gun. I will post results and photos when done (if it works), or slink away and hide, never to post again.

Or it is micro time.
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Last edited by BillL : 02-12-2017 at 06:32 PM.
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  #27  
Old 02-06-2017, 06:18 AM
Ray Brunet Ray Brunet is offline
 
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After all my shimming of my canopy frame I thought I had mine perfect. However after riveting everything I still had areas that now ended up high. I used the edge roller and brought it down a little at a time until it looked ok. the plane is almost done being painted and hopefully it wont look bad.
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  #28  
Old 02-12-2017, 05:21 PM
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Redrock Redrock is offline
 
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Hi Kelly,
I built an RV7A tip up in Ogden and had many of the same problems you've described. I believe you were recently up in Ogden looking at Kent's RV6 tip up? I ended up re-riveting my splice to raise the center. I also increased the gap between sheets by trimming the 701 some. The other thing I did that helped a lot was to feather the rear top edge (only did this in the top "flat" area) of the 771 so it went almost to a knife edge on the bottom side. That seemed to keep the edges from catching on each other. I also noticed that the force applied by the struts moved things around quit a bit with things just clecoed together. That also came into play when trimming the final fit of the rear edge of the plexiglass (mainly I found that if the 771 wasn't firmly clecoed in place the hinge area moved due to the strut forces, thus changing the rear location of the plexi). I'll be in town till Wednesday if you want to come see mine.

Brad Smith
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  #29  
Old 02-15-2017, 06:08 PM
BillL BillL is online now
 
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Default Hammering the 771/subpanel - NO JOY

No joy with hammering up the F771 at the sub panel. I measured the stagger each inch. Then a tool was made with a piece of 1/2"X2" bar stock. The end was rounded to 8" radius and an old air chisel blade welded on the end. It was at and angle to allow the anvil to fit flat against the sub panel. A mask of 6061 was made to cover the backside of the set rivets and spread the load.

It did not do a little, it did nothing. I pushed the air pressure up to 140 psi with a 2X rivet gun. I could have used my Snap-on muffler gun, but since nothing was moving at all, a different approach will be pursued. I will review it with Vans before posting.
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  #30  
Old 02-15-2017, 06:43 PM
rv7charlie rv7charlie is offline
 
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Uhhh, I'm glad you didn't damage anything.

Hard to know for sure how you were doing this, without actually seeing it. But it sounds like you were using a steel tool, and you were driving it with a rivet gun. It also sounds like the tool was placed against the bulkhead, which sounds like it may have been driving against the bend of the flange (in the 'corner') instead of out at the dimple.

Is that correct?
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