I've done the alum tubs many times and I assume they
have the same crimp joint... I start the end and curve
the upper part of the tub so its close and tap the
crimp closed right at the end... its much easier to
have 2 people doing this job... once its started then
tap the metal into the receiver groove good and about
ever 6" to 10" tap the receiver closed then once its
all in go back and tap the whole flange closed using
a wooden block and hammer
Also I use a rope to hold the radius close(tied around
the tub on the radius... about 2" from the crimp joint)