Rivet Gun Slipped

[az_gila]

Originally Posted by jcarne

I almost always do this, it avoids a lot of mistakes. I also make sure to keep pressure until a second after letting go. The end of riveting is almost always where problems arise.

One thing no one has mentioned yet is my biggest personal rule, do everything possible to squeeze a rivet before shooting one, especially AN470 rivets. I keep a thin nose yolk, 1.5", 3", 4", and the all mighty longeron yolk for my two different squeezers. Many people will argue that if you develop good shooting skills you won't need to squeeze as often; to each their own but squeezing rivets almost never goes wrong.

I agree, to each their own.

However my experience is that when you are at the longer end of the length tolerance on the rivet, I find it's easier to "tip" a shop head when squeezing as opposed to using a rivet gun.

[JonJay]

The most common problem I see is not clamping the work down to a solid bench or fixture. The second most common problem is not getting into position to be able to squarely hold the river gun and bucking bar in an athletic, relatively fixed, posture.
If your work is clamped solid and your arms are not flailing about, the quality of your riveting will improve. You don’t need tricks to make it work, just good technique, as suggested by others, and practice.

[rapid_ascent]

These are more likely with a flush set. For this type of rivet head the set should never leave the rivet head and thus it shouldn't be possible to get into the situation that you have. Obviously though you do have the situation. So... Make sure you don't have too much air pressure. For #3 rivets that means for me about 38 lbs for #4 rivets its more but maybe 40-42 lbs. If you have more structure that your riveting then you may need to turn the pressure up a little more. Make sure you are pressing the gun down when you pull the trigger and as others have said don't release the pressure on the gun until after you have released the trigger. Then wait a second more. I use riveters tape on the rivet heads to prevent them from getting banged up. This can make the set more likely to slide so you need even more pressure but it does protect the head. Others may use different types of tape but its for the same reason. For a rounded head rivet you also need to make sure the set is inline with the axis of the rivet otherwise you can get smileys next to the rivet. Just take it slow and if the air pressure is lower then you will have more control. This is a skill that takes time to develop. I've set hundreds of rivets now and I'm still not an "expert", but I'm much better than I was at the beginning.

[wjb]

Also, how you hold the gun helps alot ... this is my favorite position; trigger activated by the ring finger .. much more stable this way for me

[Marc Bourget]

Like the emphasis on rivet gun control. Direct and to the point.

The majority of the previous were all good hints, but gun control was not stressed.

I solo riveted wings on another design that had me riveting almost at arms length. Nary a "smilie"

But I was taught by guys who worked for Northrup and Lockheed (Vega Dept).

Best to form a rivet with fewest # of blows. Depending on how "fresh" the rivet, this could require higher pressures. (Rivet) Gun control saves egos!

[JonJay]

Originally Posted by Marc Bourget

Like the emphasis on rivet gun control. Direct and to the point. (Rivet) Gun control saves egos!

Very important, but you can?t have good gun control if your work is moving around or you are not bracing yourself in a good position to keep the gun stable.

[sglynn]

Also, regulate your input air pressure. You don't need 90 psi. I use 40-45 psi for 1/8 rivets. 35 - 40 psi for 3/32.

You might also use rivet tape, that green tape that is sticky on the edges. It leaves the mfg. looking nice, although they get painted. It might help with slipping off.

[wjb]

Originally Posted by sglynn

Also, regulate your input air pressure. You don't need 90 psi. I use 40-45 psi for 1/8 rivets. 35 - 40 psi for 3/32.

You might also use rivet tape, that green tape that is sticky on the edges. It leaves the mfg. looking nice, although they get painted. It might help with slipping off.

Oh .. yea; 35psi for #3's, 40psi for #4's with my setup. Completely destroyed a flap skin by forgetting to switch to the regulator, and tried to shoot rivets at 125psi. Severe sailor language ensued (apologies to our Navy alumni; I was never in the Navy, so I'm sure I didn't do it right ;-)

[EXflyer]

Never worried much about high pressure more about low. Never tap a rivet set it with as few a blows as possible. One fellow a few months back was doing that and wondered why some heads were falling off. The more blows the more work hardened the rivet becomes and gets very brittle. Those will fail down the road some where.
I do just like when painting control the gun by the amount of trigger pull I used. Photos show the gun was not square with the rivet no matter what one does this will happen if its not on the rivet properly in the first place.

[StressedOut]

I keep my compressor regulator at 90 psi. When I use my rivet gun I have a regulator at the gun inlet to adjust the strike force. That way I don't have to fiddle with the pressure at the source.

Never say never. While it's a very good idea to strike with the fewest number of blows in general, there are always exceptions. The rudder trailing edge rivets are an example. Section 5.8 says to adjust the pressure low so that it takes about three seconds to set the rivet.

I suspect (but haven't verified) that the rivet material is also a variable. At work we have a standing note in our repair procedures that says "Do not wet install rivets". I was confused about this since we wet install rivets on RV fuel tanks all the time with no problems.

The reason for the prohibition is that the sealant around the rivet sets up a water hammer hydraulic effect that can shatter the rivet. I've talked to some of our experienced mechanics and they have personally experienced this problem and had to pick rivet bits out of the messy sealant. However, this phenomenon tends to happen only with rivets made from a harder material like Monel. AD rivets are significantly softer so we can get away with wet installing them. It's possible that this same property allows the trailing edge riveting without problem.