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  #1  
Old 01-18-2012, 03:53 PM
chintangent chintangent is offline
 
Join Date: Sep 2010
Location: Loves Park, IL.
Posts: 10
Default Riveting Woes

Hello, I am currently working on the Empenage, specifically the Horizontal Stabilizer. I am riveting the skin to the rib/spar assembly. I am having a real tough time riveting the inboard section with the nose rib, forward spar, doubler plate, shim, and main rib come together. I was originally supposed to use AN470AD4, but after setting some really bad rivets, I ended up enlarging the hole trying to drill them out. Every time I use the rivet gun with the bucking bar on these rivets, the rivet always ends up bending or warping on the shop side. I am using a 3x rivet gun, set at 40psi. I've tried all different types of bucking bars, but am unable to set these rivets perfectly. I've also tried to use the Cleaveland Tools Hand Squeezer, but it doesn't seem to have enough leverage or reach to squeeze these things tight. All three holes are now different sizes: AD4, AD5, and AD6. I have not been able to work on the project for well over six months due to this roadblock. Please help!
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  #2  
Old 01-18-2012, 04:11 PM
fehdxl fehdxl is offline
 
Join Date: Mar 2005
Location: Bellevue, NE
Posts: 686
Default

I'm sure someone else will beat me to help, but if not I'll stop by next time I'm back home in the area.

I know there is a lot of help over at Poplar Grove...for example: http://www.motorcyclepilot.com/ or 'David Shelton' here on VAF.

Six months is tooo long...you'll get back on the horse in a jiffy.

Best,

-Jim

Last edited by fehdxl : 01-18-2012 at 04:14 PM.
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  #3  
Old 01-18-2012, 04:12 PM
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Don Don is offline
 
Join Date: Jan 2005
Location: Richmond, VA
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I don't claim to be an expert at riveting but I've driven most of the rivets in the airframe of my 9a, so I will claim to be an experienced amateur.

When I've bent a rivet it's usually because I picked one that was too long or the hole was too big (as a result of drilling out an earlier ooops). If you don't hold the bucking bar square to the rivet in both vertical axis, you tend to 'smoosh' the rivet. That is, drive it so it expands but the head is not symmetrically round. It is more oval and not parallel with the surface.

About the only two recommendations I'd have for you are to first, find someone in your area that can show you proper riveting techniques. There's nothing like seeing someone do it right and then have them watch you and tell you what you're doing wrong. The second thing is to practice. Van's sells two practice kits (one is a hypothetical airplane part, the other a tool box). It might be a good idea to get one or the other of these to practice on AFTER you get some one-on-one help. It might not be a bad idea to take one of the many workshops that are available.

As for 40 pounds of pressure, about all I can say is it sounds about right if you're measuring at the gun but...and it's a big but...pressure gauges differ. I've used 3 or 4 gauges during my build and I've used pressure readings from the low 30's to about 80 psi to drive rivets. In reality, 80 psi is way too much pressure but that's what my current gauge reads when I'm driving #4 rivets. I think it also depends on where you're taking the reading. That 80# is at the compressor. The rivet gun is about 75' away and I'm sure there are friction losses.

I'm not sure what to say about your parts - if some of the holes have been opened up to take a #6 rivet, frankly, I'd be inclined to buy new parts and use the old parts for practice. This may not be what you want to hear - again, I'm just an amateur and don't give my opinion more weight than it deserves. If your edge distances are okay, I'd call Van's and get their opinion.
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  #4  
Old 01-18-2012, 04:44 PM
SledDog SledDog is offline
 
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Location: Lac du Flambeau, Wisconsin
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I found these are the hardest rivets to set on the empennage. Here's what I did and they came out OK.

I used an offset rivet set with a little masking tape on the tip to keep the set from slipping. The manufactured head was placed on the forward side of the assembly.

Since the skin intersects the spar at an angle, there was some kind of optical illusion going on that made it hard for me to get the gun perpendicular to the rivet. I held a plastic drafting square against the spar and used it to see what 90 degrees looked like. I was way off without the square.

I used a tungsten bucking bar that had about a 10 degree angle on one end. This allowed me to get the bucking bar perpendicular to the spar. Also, lots of tape on the bucking bare kept things from getting dinged.

Most important, I had my ace rivet gunner drive the rivets while I held the bucking bar. Someone with a lot more skill than I have could drive these alone, but for me it was a lot easier with two people. It looks like you have a couple of offers to help. That's terrific.

If you end up sending for a few new parts, you have a lot of company.
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  #5  
Old 01-18-2012, 05:45 PM
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GAHco GAHco is offline
 
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Location: Paso Robles, CA
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Wink HI-LOKs, CherryMax or a good structural screw!

When its hard to rivet and you need it to be structural, you still have some good options beside a more expensive tool you will rareley use.

Any of these fasteners will work, with the proper head, Diameter, and Grip Length. Determine what will work best for the situation.

The Cherrymax is the easiest. (It will also expand and fill)

The Structural Screw is the cheapest.

The Hi-lok is the strongest.

Both the screw and the hi-lok should have a snug fitting close lolerance hole and a structural locknut or collar.
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  #6  
Old 01-19-2012, 07:40 AM
chintangent chintangent is offline
 
Join Date: Sep 2010
Location: Loves Park, IL.
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Default Awesome help

Thanks for the support fellas. Jim, I sent a PM to David Shelton, so hopefully someones able to swing by the garage.

Don, I've already the RV builders course, and have already set other rivets successfully. As sledog mentioned, its just a really akward angle. I have 120 psi showing on my compressor and 40 showing at my regulator right before the gun.

I hve ordered the 4" yoke from cleaveland to be able to get more reach, so we'll see how that turns out.

Ill keep you posted. Thanks guys!
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  #7  
Old 01-19-2012, 08:01 AM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Default

Quote:
Originally Posted by chintangent View Post
Thanks for the support fellas. Jim, I sent a PM to David Shelton, so hopefully someones able to swing by the garage.

Don, I've already the RV builders course, and have already set other rivets successfully. As sledog mentioned, its just a really akward angle. I have 120 psi showing on my compressor and 40 showing at my regulator right before the gun.

I hve ordered the 4" yoke from cleaveland to be able to get more reach, so we'll see how that turns out.

Ill keep you posted. Thanks guys!
Hate to see you get hung up like this for six months over one lousy rivet.

ATS http://www.aircraft-tool.com/default.aspx

has a Cherrymax Rivet Assorment and puller for less money than a set of tungsten bars.

Those hard to reach spots can be conquered quickly with Cherrymax if need be. (That won't satisfy a riveting purist but certainly will meet structural requirements.)

The name of the game here is get the airplane built and go fly.
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  #8  
Old 01-20-2012, 09:18 AM
swixtt swixtt is offline
 
Join Date: Oct 2008
Location: CAD
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Default Riveting

can you take a pic of the area you are working on?

those tight areas are so much easier with a buddy to help out. those extra yokes do help though, i must admit
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  #9  
Old 01-20-2012, 04:02 PM
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Av8torTom Av8torTom is offline
 
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Location: Yardley, PA
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Default Don't get discouraged

I had a very hard time with those rivets too; had to do them several times. I can tell you the masking tape on the machine head helps a lot as does someone else to help you buck. Alignment of the offset rivet tool is critical.

Good luck,

Tom
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  #10  
Old 01-20-2012, 05:06 PM
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bruceh bruceh is offline
 
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Location: Ramona, CA
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40 psi is too low for those AN470AD4-8 rivets. Try 75 psi.

Whenever I start messing up rivets consistently, it usually is the air pressure settings to blame.
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