[EJWash]

Sooo... After setting umpteen flush-head (AN426ADx-x) rivets in practice projects and on my RV-14 build, the manufacturer heads of my rivets are setting slightly proud of the surface. Not sure what I changed in my technique. Using a Boeing Urethane flat set, tungsten bucking bar, setting AN426AD3-4 rivets. Running 90psi to gun, pressure reduced with valve on gun.

Thanks in advance!

 

[bertschb]

Some possibilities:
1- Dimples aren't properly set (not deep enough)
2- Too much pressure on the bucking bar relative to the gun
3- Holes not straight and true

 

[wirejock]

Sooo... After setting umpteen flush-head (AN426ADx-x) rivets in practice projects and on my RV-14 build, the manufacturer heads of my rivets are setting slightly proud of the surface. Not sure what I changed in my technique. Using a Boeing Urethane flat set, tungsten bucking bar, setting AN426AD3-4 rivets. Running 90psi to gun, pressure reduced with valve on gun.

Thanks in advance!

90 PSI! A valve may work, but you don't really know what pressure is going through the gun. Everyone works different. I prefer a mini regulator on a pigtail. I set it at 22 psi for #3 rivets. 30psi for #4. Tungsten bar. 3M heavy packing tape over flush 426 rivets. Gorilla tape over 470 rivets.