Helicoil Shrinkage at Installation

Might I add to Always be sure to use the correct Heli-Coil Tap and keep that Tap separated from the rest of your Standard Taps. I can't tell you how many guys I've seen grab a Heli-Coil Tap without paying close attention to it and use it to Tap a NON-Heli-Coil Thread = Scrap Part in my Industry.

Heli-Coil Taps will have an STI marking on the Tap = Special Thread Insert and they thread the hole oversize to receive the Thread Insert.