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  #1  
Old 11-24-2017, 02:28 PM
_Alex_ _Alex_ is offline
 
Join Date: Sep 2017
Location: Bad Breisig, Germany
Posts: 7
Question RV-10 #41829

Hi all,

just started to work on VS and afraid of pure riveting quality. Herewith need your judgement on riveting of my VS stab.

If installing the Rudder Hinge Brackets I used a different rivets as Vans is calling. For VS1010 i used AN426AD4-8 instead of AN426AD4-7.
For VS1011 i used AN470AD4-8 instead of AN470AD4-7.







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  #2  
Old 11-24-2017, 05:28 PM
MartinACFactory's Avatar
MartinACFactory MartinACFactory is offline
 
Join Date: Jul 2015
Location: Montreal, Quebec, Canada
Posts: 95
Default Replace rivets ?

Hi Alex,

After installing thousand of rivets myself lately under the watch full eye of a professional aircraft assembler, please accept my comments regarding your riveting pictures:

Picture 1: From the picture quality, my impression is that all rivets on this picture shall be removed and replaced. It looks like you have overdriven each rivet, or either over squeeze them. If you do not have any, get a rivet go-no go gauge to make sure your rivets once driven are per recommended standards

Picture 2: Your rivet is dumped, it needs to be replaced. Other rivets appear OK. Maybe your bucking bar is not polished because it is leaving tool marks on the rivet

Picture 3: You may want to try to re-strike the rivet gently with the bucking bar strait to bring the rivet back to shape, else replace it

Picture 4: You have one smiley rivet head. This defect is more aesthetic than it is a problem, but it denotes good or bad quality work. I would replace. Other rivet looks overdriven and cracked. Need replacement.

This is only my own opinion. Ultimately choice to replace or keep as is is yours.

Regards,
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  #3  
Old 11-24-2017, 06:03 PM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 8,856
Smile

Try using the Rivet Specification from Vans web site and measure the shop heads carefully before replacing any -

https://www.vansaircraft.com/public/Specs.htm

As an example, the stepped rivet of the first picture may be acceptable (not pretty though) if all of the shop head is within the height limits...

c. In a stepped driven head where the minimum or maximum head height is outside Table III. (The high part may be removed to be within acceptable limits.) (See Figure 1C).
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Last edited by az_gila : 11-24-2017 at 06:07 PM.
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  #4  
Old 11-26-2017, 06:41 PM
Michael Burbidge Michael Burbidge is offline
 
Join Date: May 2006
Location: Sammamish, WA
Posts: 552
Default Quote from Manual...

You have to decide for yourself. But from the photos, which could be deceiving, none of these look that bad me. I'd take a rivet gauge to them.

I'm certainly not saying that you shouldn't continue to improve your riveting technique.

If it helps any, here's a quote directly from the RV-14 manual section 5.

"One of the common calls we get is "I had to drill out a bad rivet and now the hole is oversize. What do I do?" Sometimes this is done multiple times in the same hole and now the hole is so large that the builder has to use a bolt and nut instead of a rivet. To relieve the anxiety sometimes associated with an imperfectly set rivet and to avert potential problems arising from
ill-advised attempts at
repair, (not to say 'never
repair a rivet'), guidance
in the form of an excerpt
from the Alcoa Aluminum
Rivet Book, dated 1984,
is provided here"

"The standards to which driven
rivets should conform are frequently
uncertain. In addition to dimensions
and perfection of shape, inspection is
concerned with whether the drive head is
coaxial with the shank (not "clinched") and
whether there is excessive cracking of the heads.
It has been determined that even badly cracked heads
are satisfactory from the standpoint of static strength, fatigue strength and resistance to corrosion. (Poorly set and cracked) rivet heads were tested in tension to determine how well formed a head has to be in order to develop full strength. The tensile strengths of all the rivets were within five percent of the strongest. The test indicated that minor deviations from the theoretically desired shape of head are not cause for concern or replacement. The second rivet that is driven in any one hole [is] likely to be more defective than the first because the hole is enlarged and [the] rivet will be more likely to buckle and form an imperfect head. Tests have shown that very small rivet heads are sufficient to develop the strength of the rivet shank, even when the rivets are subject to a straight tensile pull....where a large head is not needed for appearance, smaller sizes of drive head should be used to decrease the required driving pressures."

Michael-
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  #5  
Old 11-26-2017, 07:31 PM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,510
Default I agree with Michael

Those pictures are enlarged and the exaggerated view makes them look somewhat imperfect. Certainly agree that your riveting technique will improve over time but my overwhelming concern would be that of ruining a perfect hole and installing rivets of even lesser quality as Michael has mentioned.
I also agree with the second and third poster. The rivets aren't perfect but I doubt that drilling them out and replacing them would result in a "better" installation.
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  #6  
Old 11-26-2017, 08:27 PM
sf3543 sf3543 is offline
 
Join Date: Jan 2005
Location: San Antonio, TX
Posts: 871
Default

Do a google search on MIL-STD-40007-Everyspec and look at the pdf. It will list all of the limits for driven rivets.
I think you will find that some of your rivets are within tolerance and would be better left alone.
Good luck.
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Last edited by sf3543 : 11-26-2017 at 08:30 PM. Reason: spelling
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  #7  
Old 11-26-2017, 08:47 PM
rivetshaver rivetshaver is offline
 
Join Date: Dec 2005
Location: Peachtree City Ga
Posts: 56
Default

Leave them be. They look fine. You'll do more harm replacing them.
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  #8  
Old 11-27-2017, 04:42 AM
_Alex_ _Alex_ is offline
 
Join Date: Sep 2017
Location: Bad Breisig, Germany
Posts: 7
Default Appreciate your feedback!!

Thank you all for a very useful information. IT helps me to be more accurate next time. Yes I am aware if I replace the rivet, it may cause even more problems with the new rivet due to bigger hole. I measured all of the rivets according the provided specifications.

So i replaced 3 rivets on the first picture as the thickness was at the lowest possible. This time i used AN470AD4-6 instead of ...AD4-5. I used this time also a GoNoGo gauge and sanded the rivet to get it to the right size. On the second picture i replaced that dumped rivet. On the third picture the rivet was inside of all acceptable tolerances. The rivet on the last picture was actually squeezed two times. Thats why its ugly formed, but its not cracked. But i decided to let it as it is, because its inside of accepted tolerance. This one is also the replacement for a bad one, so i decided to not to do it third time
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  #9  
Old 11-27-2017, 06:35 AM
bret's Avatar
bret bret is offline
 
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Location: Gardnerville Nv.
Posts: 2,683
Default

After doing the HS mod and drilling it all apart, I measured the rivets and holes they came out of, each hole was expanded by .010 to .015 larger from the rivet set processes, so even if you do get all the rivets out safe, now you have an enlarged hole and a loose rivet when you go to set and this sets up a problem for a redo, the rivet you reset will more than likely be worse than what the original one was.
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  #10  
Old 11-27-2017, 08:54 AM
rocketman1988 rocketman1988 is online now
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 734
Default Rivet tolerance

My tech counselor gave me an article on rivet replacement the first time he looked at my build. Reading through it verified what many have said...that drilling a rivet out for a minor error in driving it usually causes more issues than it solves. They actually did testing on rivets that had the typical errors and found that for most minor issues the overall strength of the rivet was still within 5% of a properly driven one. They also tested drilling the offending rivet out...the replacement ended up being within the same 5% due to the enlarging and or deforming the new hole when removing the old rivet.

The conclusion was that in a fair number of cases, a minor issue with a driven rivet is better left alone than trying to replace it.

I will see if I can scan the article and post it here...
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