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  #1  
Old 12-18-2018, 01:03 PM
romanov's Avatar
romanov romanov is offline
 
Join Date: May 2018
Location: Israel
Posts: 108
Question Question: strange result with a long pop rivet

Guys,

I need some advise here:

The pop rivet turned to be absolutely hollow ,
the ball and the pin who supposed to hold it
from inside are completely torn out by the rivet
gun (seems like uncontrolable process with
this kind of rivets). We aware to the fact that
this os defenitely reduces the rivet strenght ,
but how bad is it? May this be acceptable at
this specific place ? Moreover , there in an
open hole in that place , how bad is that?

The location it happened is the plastic that leads
the cable for the rudder control. Here some pictures.


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  #2  
Old 12-18-2018, 02:07 PM
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Raymo Raymo is offline
 
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Location: Richmond Hill, GA (KLHW)
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This likely occurred due to the soft plastic on the inside not providing enough resistance to the expansion of the rivet. It is non-structural, so you could leave it, but, if you have access to the back side, I would suggest drilling it out and re-riveting with a washer on the back-side that will provide the necessary resistance to the rivet expansion/compression. The washer would, of course, need to fit the rivet fairly well.
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RV-7A - Slider - N495KL - First flt 27 Jan 17
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  #3  
Old 12-18-2018, 02:15 PM
rv7charlie rv7charlie is offline
 
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If it were my plane, I don't think I would worry about it in that application, as long as you have enough of a 'shop head' on the backside to keep it from backing out. On the other hand, I've pulled a lot of rivets with several different hand pullers and a HF air puller, and I've never had one do that unless there was an issue with the rivet, or hole sizing, or *something*.

Did you make sure that they are the correct rivet for the application & hole size is correct? If so, compare the stem with one driven out of an unpulled rivet. You should see a partial cut in the stem near the ball, that creates a stress riser failure point as the ball comes up solid against the backing material. If there's no cut point, then the rivet is likely defective. (I've seen defective rivets.)

Charlie
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  #4  
Old 12-18-2018, 02:26 PM
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Mike S Mike S is offline
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Have you tried using a thin washer to spread the load when the rivet clinches ?
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  #5  
Old 12-18-2018, 03:00 PM
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romanov romanov is offline
 
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Cool

Quote:
Originally Posted by Mike S View Post
Have you tried using a thin washer to spread the load when the rivet clinches ?
The thing is that I really used the washer
and the correct rivet by the book but it looks
like the plastic on the back side yet not makes
enough resistance for the squeeze.
Anything I can do to improve it?
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Old 12-18-2018, 03:10 PM
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Raymo Raymo is offline
 
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Quote:
Originally Posted by romanov View Post
Anything I can do to improve it?

Option 1: A thicker washer on the back side might help.

Option 2: For this application, if it doesn't pull correctly the second time, go for a 3rd but don't fully pull the rivet. Stop when you think it should pop, then cut the steel center off with a Dremel.
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RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
All lines by TSFlightLines (aka Hoser)

Last edited by Raymo : 12-18-2018 at 03:12 PM.
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  #7  
Old 12-18-2018, 04:14 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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It appears to be the correct rivet based on the appearance of the end of the stem.

Are you by chance using a pneumatic rivet puller tool with the pressure set high?
If so, use a hand tool and pull the rivet slowly.
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  #8  
Old 12-19-2018, 04:58 AM
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romanov romanov is offline
 
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Talking

Thanks guys, from what I have seen so far
the best way for me is to squeeze the new
rivet just to the pop point and manually
to cut it with a Dremel.

Will order a new rivets and will post the results
here.


Cheers
Roman
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  #9  
Old 12-19-2018, 08:09 AM
rv7charlie rv7charlie is offline
 
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Did you check the stems for that 'notch' ? It should be close enough to the ball at the end of the stem that after pulling, the notch would still be inside the rivet. If there's no notch in the stem, there's nothing to help the stem snap off at the right point and at the right tension. Find a cheap hardware store rivet in your parts collection & drive the stem out backward; compare how it looks to the stem you pulled.
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  #10  
Old 12-19-2018, 12:12 PM
fixnflyguy fixnflyguy is online now
 
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Default What I do..

Pretty common for them to pull through soft material. Ultimately, the "hollow" portion will support the fiberglass fairlead. I always install these type items with Proseal on the mating surface, and dip the rivet as well. You can fill the hole and wipe it clean. it will look like a solid rivet and never come out..and it is paintable. if you keep drilling it out and re-trying, it will blow out the hole and you will have a mess. Epoxy works good also if you dont have some Proseal lying around.
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