Tubing Expander

[PS 1]

Why doesn't the 3/4" expander head work on 3/4" copper pipe? Fully expanded, it still slides in and out without any expansion. Does this mean I need a 7/8" head for 3/4" as well as a 5/8" for 1/2" copper? Thanks, Paul

[Marcus Rinaldi]

The sizing of the expander is probably by O.D., which would mean to expand 3/4" Nominal tubing you'd need the 7/8" expander. Hard drawn tubing (straight) is typically called by the I.D., while annealed tubing (flexible) is typically called by the O.D. This applies to expanders, swedgers and some benders. If you're not sure which one you need, take a scrap piece of tubing with you to match up the right one.