basenjib123 said:
... what is the functional difference between a plain ole air hammer/chisel and an actual rivet gun?
The major differences are in the trigger control, power regulation, and anti-vibration or handling of recoil features. Cheap air hammers are either ON or OFF, with little control of power (less turning down your air supply) or # of impacts. Whereas premium pneumatic rivet gun have progressive triggers, for power of strike and/or duration of # of hits; offering more response throughout the whole power range, with control down to an individual impact.
With that said, for my tin boat use the air hammers work perfectly fine. I do suggest you get some test pieces or pick an easily accessible spot ABOVE the waterline to 'tune' your setup to. I found I could pulse the trigger to deliver ~5 hits in a burst, more hits if held, less if quick off the trigger. Setup is key, especially keeping the bucking bar SQUARE to the rivet tail, as recall the one with the air hammer is hammering on the domed head.
To me, the one on the tail end of the rivet is the most critical element. When my 12-year old re-riveted her 12' skiff, she wanted to use the air gun and that was fine with me, as I had control of the bucking bar and to me, that has the most bearing on the results even when the tool/setup is optimized.
With earmuffs on, we'd bang the hull for communication. Once aligned for the next rivet, I'd tap the hull as a "Go' signal and she'd try to to deliver a ~5-shot or so burst. A single 'bang' on the hull meant, hit is again for a short burth. A double 'bang' meant hit it again for a longer burst. Many 'bang's meant OK or hold up, then we'd remove muffs and discuss.
Using a pancake compressor, we had to be patient to ensure the power built back up to the level I wanted. When I re-riveted that enire Starcraft stern (> 30 rivets alone), I used a huge 100-gallon air compressor, but with the same tooling. The point it, with either air sources the results were perfectly mushroomed rivet heads -
and that is the goal - regardless of how you get there.