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is the suggestion that i tighten slowly
No, on the time scales you're working with, metal is insensitive to the velocity of deformation. You'll get spring back, so the former needs to be smaller than the desired final size if you're reducing, and larger if you're increasing.
If the size change is only small (e.g. from an EC34-based to tube to an EC30-based one), you are not going to have problems doing it in on step, assuming a thin ductile badge. For larger changes in some materials (mostly ones which work harden), you might have to do it in multiple stages and anneal in between, but I assume the head badge maker wasn't stupid enough to choose such a material as a base. The other potential gotcha is a badge with coloured decor, as many paints and true enamels are not ductile enough to tolerate such bending after application.
gbj_tester-
the badge looks like aluminium - its a basic shield shape and has no paint or enamel so hopefully should tolerate bending quite well.
pic shows the gap between badge and head tube i need to close -
the head tube is 41mm diameter - how much smaller a tube should i bend it around do you think in order to close the gap in the pic? the downtube is 40mm...a candidate perhaps?
carson
@gbj_tester @withered_preacher
thank you both - useful ideas especially tightening over a slightly smaller tube to compensate for spring back - is the suggestion that i tighten slowly / by small increments to allow the metal time to adjust to its new position and avoid spring back?