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AD-41H rivet installation

D

Dave J

Member
Is there a best method to use when pulling this type rivet that will produce a respectable outcome? I have about 1 out of 5 that resemble a decent finished rivet. The rest end up looking bad and they also plug up the rivetgun nosepiece to where you have to unscrew it and pound out the rivet slag.
I’m using the smallest nose piece of 3/32”. The mandrel of the rivet is .063”.
I drilled a .068” hole in the side of a washer and slid over the mandrel and then pulled the rivet with similar results. It did make it easier to punch out the metal slag from the rivet instead of removing the nosepiece.
What am I doing wrong?

Thanks, Dave
 
In cases where the proper nose piece isn’t available for the tool and you don’t have a huge number to do, make a small tool with a scrap of .063 thick aluminum. Use a drill index to drill a hole, just barely bigger than the diameter of the mandrel.
Use it as a spacer between the head of the rivet and the tool by first, slipping it over the stem before inserting the rivet in the tool.
Stems getting jammed in the tool is related to the tool not being properly adjusted.
The manual that usually comes with them explains what to do.
 
rvbuilder2002 said:
In cases where the proper nose piece isn’t available for the tool and you don’t have a huge number to do, make a small tool with a scrap of .063 thick aluminum. Use a drill index to drill a hole, just barely bigger than the diameter of the mandrel.
Use it as a spacer between the head of the rivet and the tool by first, slipping it over the stem before inserting the rivet in the tool.
Stems getting jammed in the tool is related to the tool not being properly adjusted.
The manual that usually comes with them explains what to do.
Click to expand...
Yes, I basically did what you suggested with the edge of a small steel washer by drilling a small hole less than .005” over the mandrel size, then sliding it onto the mandrel and pulling the rivet. I don’t have problems pulling the mandrel, I am not getting consistent results setting the rivet. One may set and look like a good finished rivet but the next 5 look poorly done as they have for a better term, rivet slag pulled up with the mandrel and the mandrel breaking off proud of the top of the rivet.
I will get back to the shop and snap a couple pictures of the rivets.
 
rvbuilder2002 said:
In cases where the proper nose piece isn’t available for the tool and you don’t have a huge number to do, make a small tool with a scrap of .063 thick aluminum. Use a drill index to drill a hole, just barely bigger than the diameter of the mandrel.
Use it as a spacer between the head of the rivet and the tool by first, slipping it over the stem before inserting the rivet in the tool.
Stems getting jammed in the tool is related to the tool not being properly adjusted.
The manual that usually comes with them explains what to do.
Click to expand...
Here are a couple of pictures. One is a shot with the 41H rivets, bottom left looks good but the bottom right, not so much. The ones above are all lp4-3 on my flaperons (rv-12). It also shows the washer I tried to use as a smaller nose piece adapter the pull the rivet.
The other picture is a closer view of the little sleeve that is formed from the rivet slag into either the washer piece or the rivet gun nose piece if I don't use the washer. That piece needs to be punched out after most every rivet pull.
Looking ahead to the fuel tank, there are many of this type rivet to assemble the tank and I don't want to slow the riveting down while working with the limited timing of proseal hardening. 20240828_081617.jpg20240828_081647.jpg
 
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Dave J said:
Here are a couple of pictures. One is a shot with the 41H rivets, bottom left looks good but the bottom right, not so much. The ones above are all lp4-3 on my flaperons (rv-12). It also shows the washer I tried to use as a smaller nose piece adapter the pull the rivet.
The other picture is a closer view of the little sleeve that is formed from the rivet slag into either the washer piece or the rivet gun nose piece if I don't use the washer. That piece needs to be punched out after most every rivet pull.
Looking ahead to the fuel tank, there are many of this type rivet to assemble the tank and I don't want to slow the riveting down while working with the limited timing of proseal hardening. View attachment 69345View attachment 69346
Click to expand...
What tool are you using to set the rivets?
If it is a pneumatic rivet puller, what air pressure are you using?
 
I don’t have any experience with the AD41H but the AD42H with a longer grip length used for fuel tank repair worked perfectly for dozens of rivets with the Marson HP-2 puller
 

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Dave J said:
Here are a couple of pictures. One is a shot with the 41H rivets, bottom left looks good but the bottom right, not so much. The ones above are all lp4-3 on my flaperons (rv-12). It also shows the washer I tried to use as a smaller nose piece adapter the pull the rivet.
The other picture is a closer view of the little sleeve that is formed from the rivet slag into either the washer piece or the rivet gun nose piece if I don't use the washer. That piece needs to be punched out after most every rivet pull.
Looking ahead to the fuel tank, there are many of this type rivet to assemble the tank and I don't want to slow the riveting down while working with the limited timing of proseal hardening. View attachment 69345View attachment 69346
Click to expand...
Not saying this is your issue; but, two things that will certainly yield the results you're experiencing:

- Wrong grip length of fastener i.e. too long. (Most) Blind rivet mandrels are designed to break on the high side of any locking feature and below the top of the head. Yes, I know I'm being Captain Obvious here.

- If you apply any side or angle load with the puller relative to the surface. This adds stress on the mandrel at the I/F between the tool and head.

I'd double check the stack height and rivet lengths. I'd double check my technique (alignment). If both are good, I'd assume a tool or fastener quality issue. As the fastener lots get QC tested and they tend to be pretty forgiving, it's not the way I'd bet. I'd then consider borrowing a different puller and see if that makes a difference.

As mentioned, not saying this is the issue but can't think of another variable. Best of luck. Let us know.
 
Dave J said:
I've tried m12 milwaukee but have been using a manual puller most of the time with same result.
Click to expand...
I think you should investigate whether you actually have AD42H rivets that you think are AD41H.
Section 5 of the Manual has a rivet/hardware identification chart that you should be able to check the rivet against.
 
rvbuilder2002 said:
I think you should investigate whether you actually have AD42H rivets that you think are AD41H.
Section 5 of the Manual has a rivet/hardware identification chart that you should be able to check the rivet against.
Click to expand...
I have verified the skin to rib thickness of .032”. I’ve used 4 different rivet guns and spacer with minimal hole size to eliminate possible nosepiece variations of oversized holes. I have verified rivet length as AD-41H (attached picture), the AD41H is approximately .070” shorter than the AD42H.
The prediction of a good rivet vs a poor rivet set seems purely random by looking at them before use.
What I have figured out is a good rivet will pop the mandrel off with approximately one full stroke or maybe a slight second very short pull vs the bad performing rivets require a full 2 pulls. The force required to break the mandrel is very close between either rivet.
I’m questioning the hardness of the rivet material being too soft on the bad rivets allowing the mandrel to pull up too far bringing rivet material into the nosepiece? When it gets enough slag wedged into the nosepiece, the pull force is high enough to pop the mandrel?
I don’t have access to a hardness machine but would there be another creative way to check rivet material hardness.1FC7023A-38FD-4D28-B446-C2F4F9B7DE2D.jpeg
 
Dave J said:
I've tried m12 milwaukee but have been using a manual puller most of the time with same result.
Click to expand...
Have you tried one of these drill-powered pullers?

https://www.kincrome.com.au/riveters/ezi-riv-riveter-drill-attachment-kp45001

There are lots of different brands around, but they all look like they came out of the same factory.

I find they're good for a couple of reasons. First, it's easy to hold them square to the surface while pulling. Second, when used with a good drill on the screw setting the rivet can be pulled very slowly and steadily, avoiding jerk loads which can break the mandrel at the wrong position.
 
PaulvS said:
Perhaps try a different batch of rivets?
www.aircraftspruce.com

Ad-41H Closed-End Blind Pop Rivet | Aircraft Spruce

Ad-41H Closed-End Blind Pop Rivet 1/8 diameter. Used to seal tubing vent holes.
www.aircraftspruce.com www.aircraftspruce.com
Click to expand...
That would be my next move but now that I finished the flaperons, the only other place I had used them was on the doubler plates on the wings.
Looking through the plans, the fuel tank uses the 42’s so maybe I’m done with this problem. I’ve probably pulled about 10,000 rivets so far and these AD41H have been extremely inconsistent from one to the next. Very strange.
I may still try to find a machine shop that would Rockwell hardness test the few I have left over.
 
Dave J said:
That would be my next move but now that I finished the flaperons, the only other place I had used them was on the doubler plates on the wings.
Looking through the plans, the fuel tank uses the 42’s so maybe I’m done with this problem. I’ve probably pulled about 10,000 rivets so far and these AD41H have been extremely inconsistent from one to the next. Very strange.
I may still try to find a machine shop that would Rockwell hardness test the few I have left over.
Click to expand...
Did you notice any difference in the force that is required to set the rivets? Apart from the hardness of the rivet, it is also possible that there is a manufacturing variation in the mandrels that is causing them to not snap when the should.
 
PaulvS said:
Did you notice any difference in the force that is required to set the rivets? Apart from the hardness of the rivet, it is also possible that there is a manufacturing variation in the mandrels that is causing them to not snap when the should.
Click to expand...
I finally noticed the amount of pull pressure on the rivet gun was quite consistent as to when the the mandrel popped from the rivet. It was the fact that the good rivet took approximately one full stoke pull on the handle to reach the needed force to pop vs the bad rivets needing two full stroke pulls to reach the same force to pop.
Something is different with either the mandrel base shape or the material of the rivet that is requiring the mandrel to be pulled the extra length to pop. The first pull of the rivet gun would predict if it was going to be a good rivet to not. If it was a soft pull, it was going to be a bad looking rivet.
 
Dave J said:
I finally noticed the amount of pull pressure on the rivet gun was quite consistent as to when the the mandrel popped from the rivet. It was the fact that the good rivet took approximately one full stoke pull on the handle to reach the needed force to pop vs the bad rivets needing two full stroke pulls to reach the same force to pop.
Something is different with either the mandrel base shape or the material of the rivet that is requiring the mandrel to be pulled the extra length to pop. The first pull of the rivet gun would predict if it was going to be a good rivet to not. If it was a soft pull, it was going to be a bad looking rivet.
Click to expand...
I think this is an indication that the stem is pulling away from the tip of the rivet body for some reason.
Likely a manufacturing variability.
That is indicated by the stem pulling out through the top of the rivet and protruding once the stem has fractured.
 
rvbuilder2002 said:
I think this is an indication that the stem is pulling away from the tip of the rivet body for some reason.
Likely a manufacturing variability.
That is indicated by the stem pulling out through the top of the rivet and protruding once the stem has fractured.
Click to expand...
That could very well be the case. I hope I don’t run into this issue with the longer rivets when assembling the fuel tank and working with the pro seal.

Thanks to all for the ideas and suggestions.
 
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