rjcthree

rjcthree

Well Known Member
Hi, I'm riveting rear ribs to the main spar on my -9, (426-4-7) and getting a lot of edge 'smiles', I'm assuming due to gun bounce. MFG head to the rib, per instructions, requiring me to use a offset set on the gun. Any more pressure/volume, or for that matter, any less, and it gets worse. Tungsten bucking bar. About 1/3 of them now have marks that are best described in section 5 of the manual as 'ok but ugly'.

3x US Industrial gun. 60 psi, throttled about 1/3 open.


Any ideas?

Rick 90432
 
Keep the rivet set as square to the rivet head as possible.
Once the rivet is set keep pressure on the gun until well after you release the trigger.
Releasing pressure before stopping the gun means that there is a chance of a random strike from the gun and that can cause "smiley" rivets.
You might need a third or fourth hand - one to hold the bucking bar and one to stop the offset set from rotating and bouncing off the rivet head.
Just some ideas of what might be happening!
 
Last edited:
Rivet Help

Some guys use a small piece of duct tape on the face of the rivet set to minimize smileys; I just tried a product called "Snap-Soc" from Brown Tool and they work well for me-the plastic cap helps keep the rivet set centered on the rivet head. They come ten to a pack and are sized to fit various rivet sets.

http://www.browntool.com/productselect.asp?productid=659

Regards,
Mike
 
Yeah, offsets are a pain in the neck. Make sure you're letting your bucking bar do the work, too. There's a tendency to put a lot of pushback pressure on bucking bars and if that's done...the bar doesn't get the energy to do its job. (on Dan Checkoway's site, there's a really good explanation of this, using those balls where you let one end go and hits the row of balls and only the end ball moves).

Anyway, the suggestion to get some help is a good one. Get someone to handle the bucking bar, freeing a couple of fingers on your free hand up to hold it to the rivet.

If you're getting all sorts of marks on your manufactured head, your rivet set is, basically, acting as a bucking bar on it. You just need to control it better either by turning the pressure down, using a free hand to hold it on the rivet...or -- preferably -- a combination of the two.
 
Try using a different rivet set. I have one set that will "smiley" no matter what. I've looked at the set with a 10X loupe and can't see anything wrong, but I just can't make it work. All my other sets work great.
 
Good ol' 426 rivets. They were the hardests to train myself on because they are intolerant of bounce and rivet sets that are not perpendicular to the surface. Although I still use masking tape over the head for peace of mind it really boils down to technique, proper gun placment and proper pressure (psi) to the gun. FWIW Dan Checkoway has a rivet gun pressure guide for riveting on his site that I found right on for getting started. But!!:D Masking tape on the rivet head works wonders to improve your technique.
 
60 psi is too high and those regulators that mount on the gun just regulate air flow, not starting pressure, so your first blow hits with the full 60 psi. As you continue to rivet with restricted airflow, the pressure drops, and it may actually drop so low within the gun that it won't drive a 426AD4 rivet.

Dan Checkoway shows 50 as the highest pressure for 426's and 80 for 470's, and in my humble opinion 50 is too high & 80 is way too high. I rarely go much over 40, but small or excessively long air lines may require his 50 psi to maintain gun pressure. SynergyAir teaches that 40 is all you ever need.

Tony Bingelis wrote in Sport Aviation, "The proper pressure at the gun is a far lower pressure than that most builders assume to be essential. Would you believe a mere 25 psi is all you need for 3/32" rivets, and a slightly higher, 40 psi, for 1/8" rivets?" See his article at http://dad.walterfamily.org/rv/TonyBingelis/Rivet Gun Notes and Riveting Tips.html

My suggestion is to: 1. Throw away the gun mounted regulator, 2. Drop down to 40-45 PSI, and 3. Hold the rivet set with one hand while someone else holds the bar. If you do 1 & 2, you may not need the helper.

Richard Scott
RV-9A Fuselage
 
Sets and throttle...

Mel said:
Try using a different rivet set. I have one set that will "smiley" no matter what. I've looked at the set with a 10X loupe and can't see anything wrong, but I just can't make it work. All my other sets work great.
Click to expand...

Like Mel... I found one set I had was machined a bit "deep", and was absolutely not tolerant of any lack of perpendicularity. It marred almost 100% of the time

Really cheap sets may have sharper edges and will mar much easier. A ScotchBrite polish may help on these.

Try borrowing some other sets from other builders and see if it your set, rather than the technique.

I try and operate my rivet gun with the throttle near full open... perhaps with your 1/3 open the first hit is too hard (full pressure and no flow yet) and makes your set jump a bit?

Let us know what works for you... gil A
 
rjcthree said:
Hi, I'm riveting rear ribs to the main spar on my -9, (426-4-7) and getting a lot of edge 'smiles', I'm assuming due to gun bounce. MFG head to the rib, per instructions, requiring me to use a offset set on the gun. Any more pressure/volume, or for that matter, any less, and it gets worse. Tungsten bucking bar. About 1/3 of them now have marks that are best described in section 5 of the manual as 'ok but ugly'.

3x US Industrial gun. 60 psi, throttled about 1/3 open.


Any ideas?

Rick 90432
Click to expand...

Firstly, are you trying to drive these rivets on your own. If so, get a partner before you do more serious damage...like dinging the reinforcing bars on the main spar.
 
Thanks for the help

Guys, thanks fpr the help.

Experience has shown me that:

regulated and buffered (header tank) 25psi full-open throttle sets -3's nicely.

Previously 40 psi full-open throttle drove 426-4's nicely when I could get at them quarely.

I don't make smiles on the first hits - it's at the tail end of the set - like I'm losing control of the gun.

My rivet sets may suck - it was the kit from A/S US Industrial to start - it was cheap - funny how I replaced much of it. I keep learning that lesson . . .

Who's rivet sets are best? Avery? Cleaveland? I like Avery's stuff . . .

I'll be moving my regulated/header tank device to the back shop and removing my throttle from the gun next, along with masking tape, just to see . . .

Rick 90432
 
Last edited:
another use for tape - offset rivet set

When using an offset rivet set, I find it helpful to use a piece of duct tape or masking tape to hold the offset rivet set from turning in the gun as you shoot the rivet - just rotate the offset set to where the angles are best, and lock it in place to the gun with a piece of tape - eliminates another variable.
Bill
RV-6A
fuselage in progress,
Ottawa, Canada
 
OK, this is gonna sound dorky but... here goes. Become one with your rivet equipment.

See? I told you.

RV kits make lousy places to learn how to rivet. I, and this is only me, think that the psi guidelines are good guidelines....but I don't think stuff works just because you follow what others do just based on the numbers. They're a start. For example, I never use a psi lower than 60 for the "4"...and about 40 for the '3s". Why? Because it works for me, with my air hose setup (it's long).. and rivet gun setup (regulator).

Why does it work for me? Because I practiced first. Riveting is very much a 'feel" and "rhythm" thing as much as it is a technical process.

Ken Scott noted that his wife is a great riveter because she's a professional musician... she has an 'ear" for the rhythm that's involved.

I'm convinced you can take just about any reasonable set-up and make it work AFTER you get a feel for it and an ear for it. But I've also found -- and again this is me -- that you can't achieve this efficiently while working on your project.u

To me, the "feel" changes depending on the situation. An offset set -- and especially a double offset set -- is a whole 'nother beast from a short set...the bucking bar size (I'm from the stone age of RV building, I didn't buy the newfangled kryptonite-like thing ) makes a difference. How much pressure you apply on the bucking bar, how loosely -- or not -- you hold it in your hand, how long a rivet you're using. And the truly screwy part? (Again, for me and me alone)... the attitude you approach the shot with. It's very much like golf. Address the ball with no confidence... and you're screwed. Picture a good shot, be confident... and you at least still own the ball.

You really have to take some junk pieces and practice... just like any other "art." It's one of those cases -- for me -- where I've achieved a good relationship with my riveting now that I've run out of stuff to rivet. I guess it's like golf, too. A good shot on the 18th, and you want to come back and play again sometime... and build another RV.

YMMV, of course.
 
Last edited:
Knoweth What Thy Right Hand Doeth

I have to agree with Mr. Collins. Specifically, I have to concentrate more on my rivet gun hand and less on the bucking bar hand. Everytime I reverse the two I get smiles. It's a form of omphaloskepsis, or contemplating one's naval!:D
 
Rick,

Please let us know what turns out to work for you, how you cure your problem.

Also, I found that longer rivet sets tend to jump around less than short ones, which I attribute to the greater mass of the longer sets. I now use at least a 6" set unless the space is tight. Works for me.

Lastly, and FWIW, I found my Ingersoll Rand gun hits harder than my Chicago Pneumatic gun, and although both are supposed to be 3X or equivalent, there is a difference. OTH, the CP doesn't recoil as much. So there are real differences between guns that call for differences in technique.

Richard Scott
RV-9A Fuselage
 
Hockey tape

I use a bit of hockey tape (somewhat like clear electrical tape; available at sporting goods stores) on the end of the rivet set. Not sure what it does exactly (eliminates bounce?), but it helped a lot. You have to replace it every few rivets. Not my idea--sorry I can't remember where I saw it.
 
Partners

Rick... you never said if you were working alone...

If you have another person on the bucking bar, then you should use your non-rivet gun hand...:)... to actually hold the set near the rivet.

This should stop bounces and stop the set from rotating as you rivet.

I've noticed many builders do not think of holding the rivet set while riveting...
Probably thinking that you shouldn't touch the working end of a power tool...:D

gil A
 
One other trick is to use rivet tape (or something else) on each rivet. This keeps them from jumping out ever so slightly on the first hit and just makes a better looking rivet.

On my cupped rivet sets, I used duck tape. On the flat rivet sets, nothing.

Also, I used the swivel rivet set whenever I could.
 
Holding the tungsten bucking bars

Simple newbie question.....

Pictures in the Standard Aircraft Handbook illustrate the bucking bar being held 'end on' to the rivet, so the smallest face of the bar is impacting the rivet. I can understand that as the mass of the bar is aligned with the rivet and gun. Is this the intent with the tungsten bars too, or should the broad, flat face be held against the rivet? Does it matter?

Be gentle .......
 
RBR,

It is best to use the small end but whatever works works.

Here is a picture of my bucking bars:


Sometimes I use the the long side by the tip, if that's what fits.

Generally I would use the rectangular one and put the rivet on the small end.

Note the CS hole in the bar on the right. Sometimes I have used that with a rivet and rivet gun to dimple a hole.
 
"Rosie the Riveter" never met Mr. Tungsten.

RBR said:
Simple newbie question.....Pictures in the Standard Aircraft Handbook illustrate the bucking bar being held 'end on' to the rivet, so the smallest face of the bar is impacting the rivet...... Be gentle....
Click to expand...

Generally, I prefer to position any bucking bar so that the shop head of the rivet takes fullest advantage of the bar's greatest mass. Of course in the real world that is not always possible and as often as not you have to position the bar any way you can. I have no experience using a tungsten bucking bar.....we had no such tool when production types like me shot AD6 rivets all day long with common hardened steel bars. Going back a bit further, I guess "Rosie the Riveter" never knew what she was missing. Given the seemingly widespread popularity that tungsten enjoys, I'm sure to raise a cockle or two but I submit that setting those itsy bitsy teeny weeny AD3 rivets with a booster shot of tungsten is something of an optional and expensive nicety. No doubt, sales of the bars are successfully aided by glowing, even gushing field reports by satisfied users and abetted by the marketing savvy and sales skill of manufacturers and vendors of the uberbars. :)

Over time, you'll likely reach for a favorite bucking bar and I am no exception. When it comes to shooting and bucking rivets by hand, this little puppy has helped me set at least 90% of all the rivets I have ever shot into RV's or any other airplane for that matter including all the AD6 rivets set in my -6A wing spars.

​
 
Last edited:
Let me ask another newbie question:

When does one use the 2x gun? When does one use the 3x?

I searched the forum but no joy.

Thanks in advance.
 
Huck said:
When does one use the 2x gun? When does one use the 3x?
Click to expand...
Assuming you have both sizes...

Use the 3X gun on larger rivets where there is a lot of structure underneath them. Say along the longeron.

Use the 2X gun for smaller rivets and skin to bulkhead or skin to rib rivets.

I built my -9 with only a 3X gun and a friend built his -7A with a 2X. If I were to build again, I would use both.

Having used both sizes, if I had to pick one gun for the project, I would stick with the 3X. It can be turned down to drive the small rivets and doesn't have to beat the large ones a million times.
 
Last edited:
Use a long rivet set (straight)

Rick,
I rivet solo because I still don't have a partner and using the offset rivet set was almost impossible.
As you, I started riveting the ribs to the main spar with a double offset rivet set and the result was like your one... smiles!

I solved using a 7-1/2" long straight rivet set. This way I eliminated the need for a (double) offset rivet set and the partner on riveting the ribs to the main spar. There is almost no need to flex the rib apart riveting this way.

It worked very well for me.
 
You must log in or register to reply here.