Well that’s when the fun starts- trying to hold the plates, and the second snap, and the hammer, and trying to keep all square so the second snap doesn’t skid off and the head starts central because if it doesn’t……
In my somewhat limited experience double headed riveting was somewhat easier in theory than in practise, but I’m quite willing to accept that I may have missed a trick somewhere along the line.. .
Shortening – set the rivet with a plate of the right thickness, with an allowance for the excess left by a pair of small bolt croppers. Hold all steady and zap with an air hammer which has the dome cut in the tool. 1 second: perfect double round head rivet.
Air hammer – £20 from Axminster – No I don’t – wish I did