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  #41  
Old 05-25-2015, 06:18 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
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Default F-770 conical bend

This one definitely can be a gotcha.
Start by deburring the relief hole at the forward bend radius. If you're building an "A" model, I recommend not drilling the step holes until after the bend is done. The hole creates a weak spot and the bend doesn't come out uniform.
A template of the bend helps.
You'll need two pieces of scrap angle.
One holds the skin down at the bend line. It needs to be longer than the bend. Sand the edge to a radius similar to the forward end bend. No sharp edges on the forward end. Clamp at both ends.
The other angle is "torque wrench". Clamp it in place and mark the holes. Remove, punch, drill #40 and debur. Sand the angle at the forward end of it and also round the end and make sure there's no sharp edges.
Now the tricky part. Clamp a vice grip on the end of the torque angle. Have a set of smooth jaw pliers or seaming pliers handy.
Twist the bend and try to form the sharp bend without allowing the part to relax. I know it sounds dumb but that flexing is sure to crack the bend at the forward end. My first one cracked. That's why I'm posting the solution I used on the second.
The sharp forward bend needs to be centered on the relief hole.
If you can't do both, get that forward bend first and try not to allow the bend to relax. Get as close as possible and disassemble to check the bend with the template. The less flexing the better. If you get close, leave it alone and see how it fits. Best of luck.

Edit 05/27/2015
I called Vans about the crack. It was about 1/8" long. The answer was to use a chain saw round file to remove the crack plus 1/16"-1/8" beyond then fill with proseal.

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[IMG][/IMG]
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/01/2017. Plus a little extra.
RV-7A #73391, N511RV reserved (1,800+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.

Last edited by wirejock : 05-27-2015 at 12:13 PM. Reason: add text
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  #42  
Old 05-29-2015, 10:26 AM
OLDSAM OLDSAM is offline
 
Join Date: Feb 2008
Location: Tucker GA
Posts: 190
Default

I got a crack in the second skin I bent, after getting the first one right. Van's told me the same thing, but I couldn't stand it, so bought another skin and was more careful about exactly where the edge of the bench was relative to the relief hole, and how aggressively I bent it.
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  #43  
Old 05-29-2015, 01:50 PM
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aeroaddict aeroaddict is offline
 
Join Date: Apr 2013
Location: KEUL
Posts: 217
Default

When starting this step, not only do you need to deburr the relief hole at the forward bend radius, but you need to POLISH the hole edges.

I deburred then polished the hole(s) and bent both skins without cracks. It is a big bend culminating at the relief hole, there is a lot of residue stress centered at the relief hole.

Cheers
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Last edited by aeroaddict : 05-29-2015 at 01:52 PM.
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  #44  
Old 05-29-2015, 07:49 PM
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wjb wjb is offline
 
Join Date: Nov 2012
Location: Half Moon Bay, CA
Posts: 784
Default Conical bend "pusher"

I found that using "pusher" used in conjunction during the bend operation with the vice grips worked well for me. I used the piece of PVC pipe with a T at the end (which resembled my tool for screwing in rod-ends to a stunning degree) to push back on skin from the inside surface when I was loading up the vice grips. This helped to bend the skin where I wanted to bend. No cracks.

I also did a dry run with some scrap sheet to practice the whole thing ... time well spent.

Too bad you have that "big hole" in the skin near the bend ... mine has only has a small rivet there. ;-)

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Last edited by wjb : 05-29-2015 at 07:59 PM. Reason: add photo
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  #45  
Old 05-30-2015, 09:20 AM
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SkyFlorida SkyFlorida is offline
 
Join Date: Mar 2013
Location: Orlando, FL
Posts: 72
Default Wing scarf joint

The instructions for the scarf joint appear in the plans AFTER they have you dimple the skins. But in fact, you need to scarf the skins BEFORE you dimple.

Otherwise, according to Vans, you shouldn't scarf the outboard skin with the dimples. When I mentioned that the order in the plans was wrong, they told me I should read all the plans before working.

Okay.
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  #46  
Old 06-15-2015, 10:51 AM
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rgodsy rgodsy is offline
 
Join Date: Dec 2013
Location: Peculiar, MO
Posts: 40
Default Rudder Stop

I spent a lot of time and material learning how to do a rudder stop on my RV-7A. I thought I would offer this to others because once I figured it out it was easy.

[IMG][/IMG]

Setup:
Use basic material as described by Vans. Set the size by requirement for hole clearance and align bracket edge with aft edge of fuselage skin. You will need to refer to Vans drawing for basic hole location and overall sizes. Im only covering the technique that really helps.

Red line:
Attach the rough rudder stop to the fuselage and mark the spot (see arrow in ISO view) where the rudder horn contacts the rough rudder stop. Verify that rudder to elevator gap is > 1 1/8" (more like 2"). Trim as defined by the red line. Attach to the fuselage and verify the gap is still > 1 1/8". Id drill and cleco all holes to ensure the stop to skin interface surface is in the position it will be in when riveted. Any tilt in the bracket will change your gap. Also back drill the aft two holes to ensure clearance from the vertical stabilizer brace. This helps when solid riveting the aft two holes.

Blue line:
Carefully and very gradually trim the red line surface following the blue lines until the rudder skin to aft elevator tip gap is 1 1/8".

Green line:
Clean up following Vans drawing making the bracket more aerodynamic.
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  #47  
Old 06-16-2015, 04:47 PM
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wirejock wirejock is offline
 
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Location: Estes Park, CO
Posts: 2,979
Default Firewall measurement

Maybe not a "gotcha" but a but it's annoying.
The manual says to draw a center line on the firewall bottom angle then position it and cleko the bottom skin, F-772. Then it says to align the center line with the second set of holes and drill one on each end. This supposedly positions the firewall. Then on the next page it says to make sure the forward face of the firewall is 5/8" from the edge of the side skins, F-770.
Ok but the plans clearly show a dimension of 5/8" from the AFT face of the firewall to the forward edge of the bottom skin. The center line does not position the firewall exactly at that dimension. Probably was my center line. It wasn't much. 1/32" on one end. Maybe it's not a huge deal but I used clamps every foot or so and used a caliper to measure .655" all the way around. That's 5/8" + .030" (the thickness of the firewall). That positions it perfectly square and where the plans show.
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/01/2017. Plus a little extra.
RV-7A #73391, N511RV reserved (1,800+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #48  
Old 06-25-2015, 04:51 AM
bill v bill v is offline
 
Join Date: Mar 2011
Location: zeeland michigan
Posts: 121
Default f644 tipup

page 8-20 under tip-up installing front deck. add note read page 9.1 for more instructions concerning f-644
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  #49  
Old 06-26-2015, 12:19 PM
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wirejock wirejock is offline
 
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Location: Estes Park, CO
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Default 7a Gear Tower holes in F-772 bottom skin

Here's a tip for others.
When you get to cutting the holes for the gear leg towers in the F-772 bottom forward skin, this may help.

Copy the template on DWG 34a. Make a few. Punch the rivet holes out with a sharp piece of 1/16" tubing.
Remove the nutplates interfering on the F-704 top flange. You can't get the gear tower in with them there. Reinstall them later. Thanks Vans.
Remove the two forward seat floors.
Remove the two F--782B Cover Support Ribs. Also in the way. Thanks Vans.
Lay the template on the skin. Mark the line. Do the same on the F-704 flange and center skin. I used a Dremel with a metal cutter bit for all the work including the gear holes. With a little pressure, it cuts along a line and with very light pressure it barely removes material. I can hold it like a pencil and draw along an edge very precisely. go in the dire tion of tbe rotation so it doesn't gouge.
Cut the relief hole including the extra shown. It's pretty close.
Cut the relief area on F-704 also but leave extra to fine tune the fit. Watch that one rivet hole. I checked with Vans. They approved busting the minimum edge distance but remember those five holes get double flush rivets so you will countersink the F-704 flange on the inside and the bottom skin layers on the outside. The final relief should leave enough material so the countersink doesn't encroach on the edge.
Fit the gear tower first. Slowly remove material till is fits flush against F-704C. Use drift pins to make sure you have the tower where it should land. Clean up the edges.
Cleko F-772 bottom forward skin in place. Note the edge where you relieved F-704. You need to relieve the skin hole to match.
Now try to install the gear tower. Note where additional material needs to come off. It's probably on the forward and inboard areas of the hole. I use a fine tip Sharpie to make a line along the edge. This helps to see how much material is being removed. Don't take more than a line off at a time.
Keep trial fitting till the gear tower plops right into place.
Now cleko a clean template to the perfect hole. Go inside and mark the hole. Remove and cut the new template hole. Cleko to the other side and you have a mirror that should fit perfect.

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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/01/2017. Plus a little extra.
RV-7A #73391, N511RV reserved (1,800+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.

Last edited by wirejock : 06-26-2015 at 12:43 PM. Reason: add text
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  #50  
Old 06-26-2015, 01:13 PM
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bret bret is offline
 
Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,775
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I see you are coming right along. one thing that I messed up on was the floor stiffner angles, yip, got them all riveted on then go to put the floor sheet on and the holes didn't line up....what a pain to drill those angle rivets out.
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