What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

At wits' end setting AD4 rivets

ToadMan8

Member
After a very frustrating session last night, I am here for help.

There's always more to learn, but I am finished with the tail, wings, and half the fuselage on my 7A, so I would figure I have had enough "practice" to be somewhat competent at this point.

I can drive AD3's just fine, but AD4's take an inordinate length of time to set and I often cut up the factory head so badly they have to be drilled out; it's beyond a cosmetic issue.

I see videos where people are setting AD4 rivets in under a second. If I successfully set one, it can take several seconds, all the while increasing the risk of chopping up the head.

I am using:
  • 3x gun from Isham/Planetools.com that's said to make "2,160 blows per minute with a 2-7/8” stroke"
  • 1# 6oz tungsten bucking bar (and I tried a heavier steel one the size of a red bull can last night with no different effect)
  • Pressure regulator on the wall
  • Little brass "flow restrictor" on the gun

I've tried between 40 and 100 PSI at the wall along with various settings of the little brass flow restrictor. It seems that enough air pressure to set the rivet makes the gun fly all over the place, and not enough pressure never sets the rivet (perhaps work-hardens it).

I'm pushing the gun as hard as I can against the workpiece, taking care to keep it precisely aligned with the rivet, and using light/medium pressure on the bucking bar.

Any thoughts or tips as to what I could be doing wrong?? I've watched at least a dozen videos, read every article I can Google, etc. I would be very happy to bring my equipment and some scrap to KHAO this weekend if somebody will be around.

Thanks in advance!
 
Last edited:
Sounds like your technique is right. What I found was that by removing the flow restrictor from my rivet gun and then setting the pressure regulator to 30 - 35 psi gives me much better results. You might consider giving that a try.
 
With all the experience you have had, this is most likely a basic suggestion but are you 100% sure you are flush to the work, and more importantly are you clamping your work so it doesn't move? Do you have a picture of the issue? I think I know what you mean and it happens to everyone, but unless the gun is moving or the rivet set you have is the wrong size it is tough to damage the head. I put a piece of packing tape on there too just to soften the blow.
 
I don't know anything about your rivet gun, but I suffered for years with setting 1/8 rivets. Then I treated myself to a Soiux 3x. Holy smokes, that thing makes them a breeze. Brrraap, done. I don't like the trigger as well as my old one, but I now know the old one hits too fast and light for 1/8".
 
AD4 Rivets

This sounds like the rivet gun is the problem. My first rivet gun was a 2X gun that said it would drive AD4 rivets, but it really didn't have enough power. I did a demo with the same brand 3X gun and it was so easy that I bought the gun. It 3X will drive AD3 rivets with the pressure turned down a bit and I rarely use the 2X gun at all.

Also found Snap-Soc replaceable ends on the rivet set a great help.
https://www.browntool.com/Listview/tabid/344/CategoryID/34/Level/a/Default.aspx

Suggest you remove the brass regulator and use the wall regulator and practice on some test pieces. Also suggest you borrow/demo other 3X rivet guns.
 
I'm dealing with a leaky Sioux 3X, but even at my 2nd try ever at setting 4 uni's last night I was making perfect rivets... in my expert opinion :)

I had the compressor at 90 and the gun air valve at 1/2 between 0 and MAX, seemed to set well at 1 or so seconds. It takes a firm grip but not actually all that much force the gun and rivet, you certainly shouldn't have to bear weight on it.

My first attempt was... horrible. Shop head smileys, over/under driven rivets, big dents in my part (poor toolbox...). Clamping the part is key, as it turns out :D

Anyway, the Sioux seems like a very nice tool, even though I don't have anything to compare it to.
 
Last edited:
My take

I would think the flow restricter needs to be openned a few clicks. When i use the offset, then i need more pressure. But normal i just dial in more flow restricter (open up) for the 1/8 (-4)rivets and leave the pressure at 35to 50psi If the air pressure is to high, I find the gun bucks off the shop head and either damages the shop head or causes a depression of the structure/substructure. Neither is desirable. So what i found: too much pressure, structure deforms, too little pressure: forever to buck; too much flow: gun bounces too much, too little flow: tail never deforms. The ideal is the rivet mushes over like it was made out of butter, gun doesnt bounce off rivet head or cause depression of surface.
JMHO.

One problem I did have was a low flow regulator. I replaced my stock Husky (home depot)regulator with a harbor frieght version. I never had good rivets. I changed it out with a high flow one from homedepot, and no more problems. With the low flow regulator, the inital hit was good, but then the gun would die and rivet get ugly.
 
Last edited:
How long are you holding the trigger full, should only take .3 to .7 of a second, just guessing, if longer than this I would think you have an air flow restriction or not enough PSI, on light material I would use 40-50 psi, but heavy material up at the fuse forward longerons I needed 80 PSI. I too messed up a lot trying to learn this new skill requirement. just take practice.
 
Regulator

Buy a mini regulator. I love the RTI. I have short HF tool pigtails. One high pressure and one low. That saves changing the regulator so much. Put the regulator at the gun with full pressure going to the regulator. Set for about 30 psi going up based on length.
Use a heavy tu gsten
Love my Sioux 3X.
I use black Gorilla tape over the factory side.
 
my -4 rivets all had an indentation around the periphery of the rivet head. I bought new sets - same @#$% thing. I tried different pressures, couldn't figure out the problem. Since the ring was symmetrical, I knew I was straight on the rivet. I tried pressing harder on the bar vs the gun and vice versa. What solved it for me finally was using a heavier bucking bar. The one I used for the -3 rivets just wasn't cutting it. So you could try that.
 
For -4 rivets I run 60psi, and that bucks pretty quick. Can take a bit longer in thicker material, so sometimes Ill bump the pressure up a bit.

As for the factory heads getting marked up, put a layer or two of masking tape over the end of the set. A structures guy I worked with once went as far as putting prop tape over the end. The biggest killer for me was side force on the gun, once I got used to straight down pressure it almost does away with the need for tape.

Maybe it'll help maybe it wont!

Good luck

Alex
 
My guess is the brass regulator is reducing the volume of air and making the rivet gun anemic, you are getting perhaps good pressure but no volume. Remove it as someone else suggested and set air pressure in the 50-60psi range and give it a go.
 
Restrictor? Get rid of that. I run my ATS Pro 3x wide open at 100-120 psi at the compressor on 3/8" 100' line, 80psi for -3AD rivets. Tungsten bar for 99.999% of my rivets. 2 flicks of the trigger for -3 and 2-3 for the -4s, usually 3. Sets my rivets like butter.

Yes I run my gun hotter than anyone else. But it works for me and for the people Ive taught to drive rivets on my plane. And I oil the gun regularly.

I dont lean in crazy hard on my gun. Enough to keep it in contact with the metal and slightly more than the bucking bar. For me I also found using painters tape over all rivets (426s and 470s) is da bomb. Cheap, way better than rivet tape in keeping the gun from slipping off mark and if it does, it gives some cushion to that errant hit. I also took the shine off my gun heads with some emery so they have less of a tendency to slip.
 
Last edited:
As mentioned here before GET RID of tye flow restrictor and use a regulator, just like you would use for a paint gun. Either attach it at the base of the gun, which sometimes makes the gun a little heavier and awkward, or just use the regulator in the line from the compressor.
The problem with the flow reducuer is that on the first few stroke you have ALL of the tank/line pressure available until the flow is enough for the restrictor to actually work. It's way too much, comes out hitting hard, and then slows down, making it really hard to control the gun and the quality of the rivets.
If you want to see a demo so you can better understand it, take your blower attachment or paint gun and attach them first to the flow restrictor, activate the device, and then attach it to a regulated line and activate the device. A picture is worth a thousand words. :)

Vic
 
Early on I too struggled with AD4 rivets, despite no problems with 3s. I referred to these very forums waaaaaaay back then, and was told to increase the pressure off my compressor. I goosed it up to 90psi from the previous 50 and that solved the problem completely. Never had a problem after that. :)
 
Another viewpoint......

All of the rivet guns in the shop at Van's have the brass colored flow restricter valves installed (have used them for decades). The line pressure in the shop is kept at max. except for pneumatic rivet pullers.
The brass valve is used to control the guns very precisely. IMO, If a gun won't work with one installed, it is either operator error or a problem with the gun (quality?).

The bigger the rivet, the more sensitive is the technique used.
A one pound bucking bar is too small. Bar pressure is important. The gun/rivet set has to be pushing on the rivet harder than the bar. The bar has to be free to bounce on the rivet.
 
Aha! So using a bar for a -3 is not going to cut it for a -4.

That depends on what you mean by -3 and -4.....

The dash #'s are the different rivet lengths

AN470AD3 and AN470AD4 are different rivet diameters

The diameter of the rivet has more influence on the size of bucking bar (and rivet gun) than the rivet length does.

For the ideal combination, as the rivet diam. gets bigger, you would use a bigger rated gun and bucking bar. Because we only have to use 2 sizes of rivets, we can generally get by with just one gun. But my personal preference for AN3 rivets is a good 2X gun and at least a 3X for AN4 rivets (and a bigger bucking bar).

The rivet length still has some influence on the riveting force that has to be applied because longer rivets usually mean they are being installed in heavier structure. The heavier structure isn't influenced/vibrated as easily as light weight structure but that can usually be compensated for by simply turning up the gun a bit.

It is for this reason that I always use an inline restrictor/regulator at the gun.

An example is if riveting on a wing skin. When out in the middle of the skin setting rivets that attach a span wise J-channel skin stiffener, it will take a much lower air setting than it will when you have moved to the spar and are riveting on the spar flange near wing ribs. The structure is much stiffer and more resistant to the influence of the rivet gun. With experience, you can learn to read the structure and the setting process of each rivet as you move about and make small adjustments with the gun mounted regulator as you move between different areas. If you are setting with a wall mounted regulator it is not practical to keep going and adjusting it.

Is this necessary to be able to do a decent riveting job?
No.

Once someone gets good with a particular rivet gun they can do an acceptable job on a wide range of situations with just one setting, but my experience has been that the best (flush riveting in particular) riveting finish is attained by picking the tools that match the overall situation, and then adjusting the gun to match the rivets being set at the moment.

Back riveting is a whole different situation. Because the rivet gun is not needing to have a vibration influence on the structure, the setting on the gun is pretty much a set it and forget it type of thing. This is just one of many benefits of back riveting flush riveted skins (which in our shop we do every chance we get).

One other thing that has a big influence on rivet setting performance (can cause problems even if everything else is perfect) is the relationship between pressure being applied to the rivet with bucking bar, vs pressure applied by the rivet gun.
The bucking bar has to be allowed to bounce. If you are pushing too hard, that will limit this ability and transfer back to cause the rivet gun to bounce.
So a common cause of smiles in AN470 rivets is that
1. The gun bounced because it wasn't being pressed hard enough against the rivet
2. the bucking bar was being pressed too hard against the rivet
3. a combination of 1 and 2.

Bottom line.... for any conventional riveting.... the set on the rivet gun should be pressing harder against the manufactured head of the rivet that the bucking bar is against the shank of the rivet.
For back riveting, it is exactly the reverse.... the bucking bar should be pressing harder than the rivet set.
 
Last edited:
I had purchased a used gun and had the same problems. I purchased a soiux 3* gun, set it at 38 lb at the wall and all my problems went away.
 
That depends on what you mean by -3 and -4.....

The dash #'s are the different rivet lengths

AN470AD3 and AN470AD4 are different rivet diameters


.


Ya I meant ad3 vs ad4. I have a small dia light weight hose for the last 25 ft. I bet I am getting major losses from that.

Your post was very informative Scott. thanks
 
Back
Top