Hardtop Assembling - need rivet peening assistance

[Gerry P.]

I'm assymbling the hardtop for a '56-57 and having trouble peening the solid stainless steel rivets. I'm at the point of attaching the the side hold down brackets (Y bracket). In talking with Matt at Glassworks, he said to apply the air hammer to the head (rounded top) of the rivet and hold the bucking bar to the side which gets peened. I've done this with the rat-a-tat for a minute or more and the picture below shows the result with very little peening (peened rivet on the left, right rivet is unpeened). I've tried with 30 to100+ pounds of pressure through the air hammer and held the rivet shank tool tight against the rivet. If I let off a bit on the downward pressue, the tool bounces uncontrollably. For a bucking bar, I've used everything from the CV axle end in the picture to a rail road rail to a large heavy anvil. Result is the same. On practice rivets, I've used the air hammer on the side to be peened with a little more success, but still took a long time.
Advice welcomed on how to properly peen the rivets or what I'm doing wrong.
Thanks, Gerry

[Richard G.]

Re: Hardtop Assembling - need rivet peening assistance

Have you tied a lower pressure at the rivet gun?

[Gerry P.]

[Perry M.]

Re: Hardtop Assembling - need rivet peening assistance

I believe the problem is with your air tool. I used to get similar results with my air tool that is small like yours till I bought a heavy duty gun from Boeing surplus. Now I don't have a problem, even replaced the rivets on my '57 Nomad ball joints with it.

[Gerry P.]

Re: Hardtop Assembling - need rivet peening assistance

Thanks Perry - I was wondering if that was the problem. I have the air tool pictured which originally was my dad's and who know how old it is and I have another smaller one which came from O'Reilly's. I hate to buy another one for just a handful of rivets so may try a rental store and see what they have. Right now, as much as I try, the rivets just won't peen with the air hammers I have.

[Perry M.]

Re: Hardtop Assembling - need rivet peening assistance

A stainless rivet is the hardest material to peen. The gun I have has a longer barrel so you can use one hand to pull the trigger and the other to hold onto the barrel which gives you better control. If you were in my area, I would let you use it. Good Luck

[Rod K.]

Re: Hardtop Assembling - need rivet peening assistance

I've done this with a cheap Harbor Freight air hammer, but I did it the opposite from what Matt suggested with the air tool against the end being peened and the head being backed up with a formed seat so it wouldn't deform the head. I believe you need to be sure the rivet is backed up solidly like on an anvil sitting on the floor. Hand held anything I think would allow the rivet to move enough to negate the peening force. I did mine against a workbench mounted vice and it worked well with just enough air pressure to insure the hammer cycled positively. I also had a tool with the tip hollowed out to form a dome like the original peened shape. Start with low air pressure and increase until you get the desired result.

[Gerry P.]

Re: Hardtop Assembling - need rivet peening assistance

Perry, thanks for information and offer for using your gun but we're too far away to make that practical.
Rod, your approach has merit but what I think I need is a better air gun that has the power to peen, then it is a matter of technique. You mentioned you used a Harbor Freight gun. Their website only shows one for $14, is that the one you used?
Thanks again for your feedback.
Gerry

[Rod K.]

Re: Hardtop Assembling - need rivet peening assistance

Gerry, I've had this hammer for a lot of years so can't really say whether it's the equivalent of the current HF offering, only mentioned it to say that it probably shouldn't take anything very special to set these rivets even tho they're stainless. I'm sure they'd be a fairly soft grade of material since they're intended to be deformed. Also set a lot of aluminum body rivets with this gun and had to set the pressure pretty low to prevent damage to the fiberglass.

[Gerry P.]

Re: Hardtop Assembling - need rivet peening assistance

Follow up, I took another look at my rivet gun and realized the barrel wasn't completely screwed tight. After tightening, it has a lot more oomph and now does the job. It then became a matter of air pressure adjustment.

As a side note, the newer (and a little smaller) gun I purchased from O'Reilly a few years ago has a slightly smaller barrel than my larger & older gun. The peen tools I'm using have a diameter of .40" (10.15mm). The O'Reilly gun tools have a .395" (10.0mm) diameter. At first I didn't think too much about it except I had to take the rivet gun apart to get the rivet tool dislodged. I then realized, the tight fit impeded the rivet action. The rivet tool at home depot I looked at had the .395" diameter tools so am thinking all newere guns are metric. The rivet tools I have are inches so a new gun would require diff ritvet tools.

Sorry for the long diatribe but thanks guys for your assistance in helping me get to the endgame.
Gerry