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  #1  
Old 01-12-2012, 01:29 PM
JOEPILOT JOEPILOT is offline
 
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Location: STATEN ISLAND, NY
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Default Blind Rivets

Hi all my name is Joe Monderine. I'm new to this forum, but I've been following RVs since I started flying in 1993. I hope this is not a stupid question, but has anyone built an RV9 or 9A using blind rivets? If so any data on building time saved or performance lost. Thanks, Joe
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  #2  
Old 01-12-2012, 02:18 PM
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comfortcat comfortcat is offline
 
Join Date: Jul 2005
Location: Southern California
Posts: 616
Default Blind rivets?

Greetings!

Cons for pull rivets:
* Cost
* Weight

Pros for pull rivets
* Just as strong,
* All sizes available
* Nominally easier for tight locations and one person.

I actually asked this question before I started building my 9A but I did that for the wrong reason. I thought I'd need to use blind rivets because I was unskilled / unable to use regular rivets. As it turns out, Riveting is easy. Regular rivets are CHEAP (compared to pull-rivets) and lighter and look nicer.

The reality is you will probably not use very many pull-rivets to build your airplane. Can you? Sure. Pull rivets are just as strong as bucked. Can you use them in the tough spots where bucking is hard? Yup. I have lots.

I'm not one of those macho guys that see a pull rivet as a sign of defeat.

Hey, build a Van's tool box and you'll see what I mean.

Dkb
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  #3  
Old 01-12-2012, 02:51 PM
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KRviator KRviator is offline
 
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I used several hundred MK-319-BS rivets to close out the QB wing panels, and a few pop rivets on various parts of the tail as well. I'm building essentially single-handed a lot of the time, so they work for my application. And I saved a *lot* of hassle when it came to it. When it's time for the RV-10, I'll do the same thing.

There's nothing to be gained by tying yourself in knots tying to buck a solid rivet, when a pop rivet is just as strong and much easier. And you eliminate the risk of having to drill out a mis-set solid rivet in an awkward spot, perhaps several times...

The cost will be a factor in using pop rivets, but you can certainly offset the weight by using modern avionics. For example an Xcom radio over an SL-40 saves over a pound. A single EFIS & EMS will save perhaps 10 pounds over standard instruments.

Some will call it cheating, but these are probably the same people who thing anything other than a standard kit is cheating as well. But it's my plane, so it's my rules.
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  #4  
Old 01-12-2012, 04:00 PM
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Niko Niko is offline
 
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I would be carefull replacing all the solid rivets with blind ones as depending on what type of blind rivet you use they are not necessarily as strong as solid rivets. The problem comes in the head of the rivet which is essentially a hollow cylinder that has been turned over. Assuming same material for both, in tension, these rivets are much weaker than a solid rivet assuming same material for both. The hollow head, in certain cases, can also result in reduced joint shear strength because the head can't transfer moment as efficiently as a solid rivet.

You can make up for this by using a steel or monel or other material for the outer cylinder of the blind river. Another thing coming to play is that after many years of use, the mechanism that holds the steel stem in the center of the blind rivet could wear out and fall off leaving you with only a hollow aluminum rivet thats much weaker in shear than a solid rivet. Thats the reason the better (read more expensive) blind rivets like cherrymax are around. They have a much better mechanism for holding the steel stem in place.

In other words, if replacing a rivet here or there , as long as they are not in a critical area, I would not worry about it, however, I would not undertake a wholesale replacement of rivets from solid to blind unless the designer accounted for it.

Hope this helps
Niko
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  #5  
Old 01-12-2012, 06:56 PM
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Walt Walt is offline
 
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Quote:
Originally Posted by KRviator View Post
There's nothing to be gained by tying yourself in knots tying to buck a solid rivet, when a pop rivet is just as strong and much easier. And you eliminate the risk of having to drill out a mis-set solid rivet in an awkward spot, perhaps several times...
In the world I came from in aircraft repair and manufacturing, you could not substitute blind rivets (including cherry-max) for solid rivets. A repair done with cherry to save time would be time limited and considered a temporary repair.

"Pop" rivets of any kind are not equivalent to solid rivets and should not be arbitrarily used as a substitue for solid rivets unless approved.
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  #6  
Old 01-12-2012, 07:03 PM
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Vlad Vlad is offline
 
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Welcome Joe! Come to Linden some day I will show you all those blind rivets KRaviator is talking about If you like them we may go for a ride.
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  #7  
Old 01-12-2012, 09:18 PM
Lars Lars is offline
 
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Quote:
Originally Posted by Walt View Post
In the world I came from in aircraft repair and manufacturing, you could not substitute blind rivets (including cherry-max) for solid rivets. A repair done with cherry to save time would be time limited and considered a temporary repair.

"Pop" rivets of any kind are not equivalent to solid rivets and should not be arbitrarily used as a substitue for solid rivets unless approved.
You do realize that Alcoa, for example, doesn't even manufacture traditional driven rivets anymore. They do make blind fasteners, such as HuckMax rivets, that are anything but temporary. I've been helping a local A&P/sheet metal wizard manufacture a set of crop duster wings per plans to an STC with nary a traditional driven rivet in sight. Beautiful wings with steel (gasp!) spar reinforcements. The puller for the huck rivets makes an oh-so-satisfying sound when the pin snaps. Lots of Cherry rivets in that set of wings too.

OK, that said, I agree with you in principle. If you aren't familiar with joint design and the specification of rivets in structures, it's dangerous to make arbitrary substitutions. But pulled rivets/fasteners, properly chosen, are every bit as strong (or stronger) than the driven alternative.

And I have to admit that, as I type this, I'm looking at my well-worn 1958 edition of Alcoa's "Riveting Alcoa Aluminum".
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Last edited by Lars : 01-12-2012 at 09:40 PM.
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  #8  
Old 01-12-2012, 10:46 PM
chevytoo chevytoo is offline
 
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Location: Langley B.C.
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There is one great difference between blind rivets and solid rivets. A solid rivet when properly set will swell to fill the hole and give you a tight joint. A blind rivet will not. OK. The manufacturer of Huck blind rivets will tell you that the first action is to swell the rivet and that may be true but there is still a space between the mandral and the rivet so over time the rivet will work and smoke. Bell helicopters uses Cherry rivets in the tail booms of many of their helicopters but the joints are also prosealed to stop the joints from working.
With a bit of practice you will be setting solid rivets faster and easier than it is to install a blind rivet especially where you can use a squeezer.
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  #9  
Old 01-13-2012, 06:39 AM
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Walt Walt is offline
 
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Quote:
Originally Posted by Lars View Post
You do realize that Alcoa, for example, doesn't even manufacture traditional driven rivets anymore. They do make blind fasteners, such as HuckMax rivets, that are anything but temporary. I've been helping a local A&P/sheet metal wizard manufacture a set of crop duster wings per plans to an STC with nary a traditional driven rivet in sight. Beautiful wings with steel (gasp!) spar reinforcements. The puller for the huck rivets makes an oh-so-satisfying sound when the pin snaps. Lots of Cherry rivets in that set of wings too.

OK, that said, I agree with you in principle. If you aren't familiar with joint design and the specification of rivets in structures, it's dangerous to make arbitrary substitutions. But pulled rivets/fasteners, properly chosen, are every bit as strong (or stronger) than the driven alternative.

.

If the structure or repair is specifically designed to use some of the higher end blind fasteners like huck then that's great, but that is not really what is being asked by the original poster. I might also add that all of the huck and cherry max products are not available in a -3 size, minimum is -4 hence the use of the cheaper cherry 'N' rivet which is available in a -3.

Below is Quoted from another source:

"Two cheaper versions of Cherry rivets are available. These are called Cherry "N" and Cherry "Q". Cherry "N" rivets are non-structural. Cherry "Q" rivets have limited structural use. They do provide a high shear strength. A number of kit manufacturers use the Cherry "Q" type rivet in the construction of their aircraft."

The MK319BS rivet is an 'N' cherry.
Cherry 'Q' rivets are not available in the -3 size
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Walt Aronow, Dallas, TX (52F) RV7A, IO360, C/S, 1500+hrs

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154

Last edited by Walt : 01-13-2012 at 06:43 AM.
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  #10  
Old 01-13-2012, 08:58 AM
JOEPILOT JOEPILOT is offline
 
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Thanks to all who replied, Joe
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