Countersunk rivet problems

[flyingtaran]

hi all,
i'm only fairly new to the rv and i've only just started riveting the horizontal stabiliser skin to ribs and i'm encountering problems with my countersunk riveting, I did the first one ok, but now on the second & third i reckon i've probably drilled out and re-riveted them about 10 times, they are just not sitting straight & flush, everytime I drive them they end up sitting up.
this has been doing my head in to a point where i haven't worked on it for a month, any suggestions would be great,
heres a few pics,



Thanks

taran

[FlyingArcher]

Hi Taran,

It would help to know which riveting technique you used here, but based on the parts, I guess you're using a rivet gun with mushroom head + bucking bar.

I think what you see is because your parts were allowed to move during riveting. I would anchor/clamp the assembly to the bench so that when you push on the skin with your gun, it stays in place. Also, don't push hard on the bucking bar, just prevent it from bouncing laterally out of the shop head you're forming.

You should try to find some videos on the net (there are many available, starting by the EAA website) that demonstrate the proper riveting techniques, I can tell you that it really helps. I NEVER had used a rivet gun or squeezer before starting my project and looking at these videos gave me much more confidence.
Hope this helps and don't give up, you'll be an "expert" soon.

[RV6AussieNick]

Hi Taran,

Looks to me that you may not be holding the gun square to the job, when you rivet do you see a slight mark next to the rivet, if so this indicates that your gun isn't square to the job, the hitting force is being delivered next to the rivet instead of into it. It may take a few rivets to get your eye in to square the gun up, if you have a rivet helper they might be able to help sight the gun up before riveting.

Cheers,

[Richard Connell]

Gday Taran,

Are you riveting by yourself?
This looks like the rivet gun is bouncing on the surface allowing the rivet to compress on the wrong side. The outside. And possibly between the rib and skin as well.
You need more force holding the rivet gun than the bucking bar- so the bucking bar does all the bouncing, not the rivet gun.
Where in Sydney are you? I'm happy to pop round and give you a hand sometime if you need.

Cheers

[flyenforfun]

One guy said not holding the rivet gun flush.. not sure if you are doing this or not, but the best flush riveting tool I used on my entire project was the pivoting rivet set for my rivet gun. It is a flat flush rivet set, surrounded with rubber, and its ball mounted so even if you dont have the rivet gun perfectly square, the set will lay flat on the surface.

Anywho, I think maybe you need to push harder with the rivet gun and let the bucking bar bounce a little more, let it to the work. Ive found the less you push with the bucking bar, the faster the rivet goes down, just dont let it bounce around and damage the metal around it.

If you don't drill the hole straight this is what happens. Use a drill bushing to get it square.

[Av8torTom]

taran,

Like others have said - looks like you're not holding the rivet gun firmly enought against the machine head of the rivet. When this happens, the bucking bar will push the rivet out back towards the gun. Also, if you don't already have one, I recommend a swivel mushroom rivet set. Allows you to be off slightly getting the gun perpendicular to the work. Don't get discouraged, you'll get there.

Tom

[rzbill]

+1 for comments about bucking bar pressure and clamping of the work such that you can apply hand force to the gun without the workpiece moving.

As a beginner, you have not developed the "feel" yet. Don't worry, I'm sure you will get it quick when you find that sweet spot.

What air pressure is supplied to the gun?
It is possible that it is too high, causing the gun to bounce no matter how much you try to hold it on the work.

For my equipment, around 40-45 psi worked well for #3 rivets. It may be different for you.

I agree with the other comments above, with the small caveat that when I want a rivet REALLY flush, I use a solid set with rubber ring and not the pivoting mushroom set mentioned above. The pivot does make a difference in how hard it hits.

Otherwise the pivoting unit is great for solo riveting.

[carrollcw]

I am also a fairly new builder. Just finishing my empennage. Definitely looks like not enough pressure at the gun / too much pressure at the bucking bar (been there done that).

Also, I too use the swivel flush head with the rubber around it. If you are using it too, you MUST shave down the rubber head so the surface will sit flush on the rivet. Otherwise, the rubber will keep the flush head too far from the surface (unless you use an extreme amt of pressure) and every rivet will turn out that way. If that is the problem, just use your scotchbrite wheel and carefully grind the rubber down flush.

[jrs14855]

The rating of the rivet gun is also a factor. The lower the rating the harder the gun has to work and the more it will move around.
economy gun not rated
2x gun 5/32 rivet
3x 3/16 rivet
4x 1/4 rivet.
I would recommend the 3x