Pirate

Pirate

Member
I installed my first CS4-4 flush rivet with a hydro-pneumatic puller today and the rivet didn't snap at the end of the pullers cycle. So I cycled the puller to finish the rivet. The rivet snapped above the flush head.

Do I need to drill this out and go again? Or can I just remove the excess center? I installed 4 of these and 2 of them failed like this one.

Thanks,
Tim :confused:

tumblr_mkby1hLN1j1s32mfwo2_1280.jpg


tumblr_mkby1hLN1j1s32mfwo1_1280.jpg
 
Tim,

I'd knock out the mandrel and drill it out. The more important issue is whether you need a new puller that will pull the rivets as designed. Did you try using a hand puller on the CS rivets?

Rich
 
My plan was to switch to the had puller for the rest of the CS4's. I thought at first it was a one off but since it happened twice I figured it may be a puller issue.

What's the safest way to remove the mandrel since it's now raised above the rivet head?
 
Pirate said:
I installed my first CS4-4 flush rivet with a hydro-pneumatic puller today and the rivet didn't snap at the end of the pullers cycle. So I cycled the puller to finish the rivet. The rivet snapped above the flush head.
Click to expand...

Are you sure you are using the correct rivet?
Is it possible that CS4-3's are called for in this location?

When the stem pulls above the rivet head it is an indicator that the rivet is too long of a grip length for what is being riveted.

I also can tell that the tip on your tool has too large of a hole in it (the raised ridge being left in the rivet head around the stem. The hole should match the stem diam as close as possible. It is not likely that this is causing your installation problem, however.
 
Pirate said:
What's the safest way to remove the mandrel since it's now raised above the rivet head?
Click to expand...

Pirate... I use a modified spring center punch and a piece of wood with a hole in it as a backing plate to punch the mandrel back in below the manufactured head. Then I drill a #31 hole in the head. Then I break off the head using a stationary punch as a wiggling tool. Then I again use the modified spring center punch and wood backing plate to punch out the remaining rivet/mandrel. I second the ? if the rivet is too long for the application.

Jeff
 
I triple checked the plans (Page 09-03) and it only calls for CS4-4's. I think 4 of the CS4's called out in the plans could have been -3's instead of -4's due to thickness of the material. The puller I am using is from Cleveland Tools made by NUMATX.

Pic:
shpp3150lg.jpg


I struggle to think this puller wasn't designed to handle these rivets. All the other rivets were pulled flawlessly.

Jeff, I'll give that a go tonight.

Cheers,
Tim
 
Im with Scott's thought that the hole in your puller is too large. I didn't understand that you needed to change tips for the different thickness rivets and thought as long as the river fir in the tip, it was OK. After a few messed up rivets, I figured it out and never had a problem after the change.

It looks like it could have used a bit deeper dimple to be flush, but pictures are not always the best way to determine the depth.
 
I agree that the hole in the tip could be too large. But one further thing to check: spin off the nose of the rivet puller. Not just the tip with the opening, but the entire chrome nose piece. Inside, there is a heavy steel sleeve, that the rivet stems slide into. Sometimes this sleeve backs off from the other tailpiece, closer toward the back of the gun. Just make sure the inside pieces haven't worked their way apart somewhat. If so, and I've seen it happen a lot with my el-cheapo puller doing just this, sometimes it can break the mandrels in non-traditional places.

Just something VERY quick and easy to check.....
 
Pirate said:
I triple checked the plans (Page 09-03) and it only calls for CS4-4's. I think 4 of the CS4's called out in the plans could have been -3's instead of -4's due to thickness of the material. The puller I am using is from Cleveland Tools made by NUMATX.

Pic:
shpp3150lg.jpg


I struggle to think this puller wasn't designed to handle these rivets. All the other rivets were pulled flawlessly.

Jeff, I'll give that a go tonight.

Cheers,
Tim
Click to expand...

I also confirmed that it does call out CS4-4 's at this location so I suggest the following...

Change the nose piece on your puller to one with a hole that closely matches the stem on the rivet.
Turn down the line air pressure to about 60 PSI and try and pull a rivet.
If it won?t pull the rivet, turn it up in 5 PSI increments until it does.

It may be that your fancy puller is able to pull very hard, very rapidly with high pressure, allowing the stem to pull in further as it is breaking off.
 
Gary - This is a pic of what the puller looks like when I took off the chrome housing. I adjusted the mechanism as far aft as possible. This allowed the puller to correctly separate the mandrel on a few test rivets. If I adjust it forward like I found it, the rivets won't separate. The stop nut was loose too.

dsc00673ax.jpg


Scott - The puller actually pulls rivets rather slowly. Very similar to any other puller I've used. Here's what the tip looks like that came with it. Does it need to be tighter than this? Its the exact same size as the one that came with my hand puller for 1/8" rivets.

NUMATX head:
dsc00670m.jpg


Hand Puller:
dsc00671tx.jpg


Thanks,
Tim
 
Not being a -12 builder (yet!) I was wondering why a CS4 there instead
of a standard rivet when those on either side are? Can't use a squeezer
for that hole?
 
Tim,
In your top photo, the two black pieces to the right, are the exact ones I was mentioning. I'd bet that by mating these two pieces, you'll find the rivets much easier to pull, and breaking where they are supposed to! I see a small gap between them, and that's not supposed to be there. I believe the tip size is fine. I think you'll find it was those two black pieces being apart....the breaking of the mandrel obviously occurs within those two pieces. If it's out of adjustment, nothing will pull the way it is designed to.

Looks like the problem has been solved!?
 
My pneumatic puller from Cleaveland was very happy with 40 psi air. Nice smooth pull. Too much or too little pressure is not good. Built the whole plane with 40 psi.
 
Pirate said:
Scott - The puller actually pulls rivets rather slowly. Very similar to any other puller I've used. Here's what the tip looks like that came with it. Does it need to be tighter than this? Its the exact same size as the one that came with my hand puller for 1/8" rivets.

NUMATX head:
dsc00670m.jpg


Hand Puller:
dsc00671tx.jpg


Thanks,
Tim
Click to expand...

Most (but not all) pullers come with an assortment of tips for different size rivets. The one you are using looks like the hole is about 1/2 again the diam. of the stem. Ideally it would be just slightly bigger than the stem. It will not hurt anything, but it will effect the aesthetic appearance of the skin rivets on the exterior of the airplane. Call Mike at Cleveland Tools and see if it was supposed to come with other tips, or if they have them available.
 
Chino Tom said:
Not being a -12 builder (yet!) I was wondering why a CS4 there instead
of a standard rivet when those on either side are? Can't use a squeezer
for that hole?
Click to expand...

There are several rivet locations in the RV-12 that can't be accessed with standard yolk squeezers. And there is no requirement to use a rivet gun/bucking bar for the -12, so Van's specifies exactly where to use the flush pull rivets instead. You really need to follow the plans to the letter to avoid getting into trouble.
 
PilotBrent said:
<snip> You really need to follow the plans to the letter to avoid getting into trouble.
Click to expand...

Amen to that!!!
and I'll add... Make no assumptions of assembly logic or order. Case in point - if your building experience is based on any model less than -10, you may have wing walk doublers left over after you've finished riveting on the top skins. What?... wing walk doublers on the OUTSIDE?
Just sayin'
 
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Ernie,

For the most part I agree with your conclusion on build order, but I bought all the airframe kits at once and mixed it up a bit with the fuselage and finish kits which made the build a little easier in my opinion.

Rich
 
OK, I see that this is in the RV-12 post area...I built a -6A. I my case, there are a number of areas that call for flush head pulled rivets. Offhand, I don't recall the exact p/n or designation. I had a similar problem as the OP, and came up with a solution to prevent the raised burr left by a too-large rivet puller nose piece.

If you look at a Cherry-Max rivet, you will find that it contains a "driving mandrill" that looks like a very small washer resting on the flat part of the flush rivet. When the Cherry Max rivet is inserted into a hole and then set, the pin mandrel brakes as you would expect, and the little washer flies off /drops to the floor/ whatever. You can retrieve these little washers and use them on other types of flush rivets to eliminate the raised burr that is caused by the not so perfect fit with other pop rivet tools.
 
dsc00673ax.jpg


Tim,

Thanks for forwarding me the link to this thread. I have been absent from VAF for far too long as we have been consumed with tool development. The question here is one that many users of the power pop rivet tools don't understand, so I thought I should make the reply public.

As others have said you want to use the smallest nosepiece that the mandrel will fit through.

For the greatest stroke the hex nut shown in your photo above should be placed in the furthest aft position, then the two black barrels should be tightened up against them with no gaps. Normal rivets should then be able to be pulled in one stroke.

When pulling shorter rivets, you may want to run all three pieces forward a bit (still tightened together) to limit the amount of recoil experienced. If you are like me, I push a bit on the material to make sure the rivet is seated properly in the material. With too much stroke, the puller will recoil when the mandrel breaks and leave the material. The manual pressure being held causes the user to hit the skin with the puller head. When adjusted correctly, the puller should just click when the mandrel breaks, with no noticeable recoil. As a measure of security, I generally hold the puller nose in a saddle with my left hand, placing my thumb and index finger on opposite sides of the nose piece and against the skin. This allows me to control the nose as the degree of freedom is added when the mandrel breaks.

Now to address your actual question... I would think that it is either too long of a rivet for the material, or more likely the two barrel parts are not jammed tightly together as shown in the photo.
 
Quick Follow Up

Tim sent me a photo of the smallest nose-piece for his puller. There was a countersink where the maker had 'overdeburred' the hole. (Sounds like other common forum topics). This will have the same effect of sucking the rivets up into the nose-piece as using the wrong sized nose-piece. I have faced off flat, one of the nose pieces that we had here for Tim. Others may wish to do the same to control the look of the finished rivets. Feel free to send me your nose-pieces if you wish and I will do the same and return it to you. Really I am just trying to set the internet record for the number of times "nose-piece" is used in a paragraph.

-Mike
 
Canopy rivets

I ran into the same issue using a hand puller. I also had 3 or 4 rivets that were not CS type and didn't notice until after pulling a few. Sorted out the pack as received from Vans and found more!

Wally
RV-4 paint prep
 
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