Although I had previously dimpled the left hand structure using standard 3/16" dimple dies, some Internet research shows that other builders have used the very slightly deeper dimples provided by the 3/16" Tank Dies.
Consequently I went over the left sub-structure again with those dies, and also used them on the right sub-structure. This time I used the dimple dies in the pneumatic squeezer rather than the modified vice-grips I'd used last time. What a difference! The pneumatic squeezer is an expensive bit of kit, which cost me about $450 *without* the yoke - and after today I don't grudge a cent of it!
