Stripped a thread? You need an insert
Aluminium threads have a nasty habit of stripping just when you don’t want them to. Here’s how to fix them for life with thread inserts
EVEN THE MOST cautious mechanic and fastidious applicant of the torque wrench will occasionally strip a thread. It’s frustrating and you never quite get used to the stomach-lurching sensation when a thread gives way just on the point of a fastener tightening.
Still, it’s all fixable and there are a number of thread insert solutions on the market. ‘Helicoil’ has become the generic term for stripped thread repair, much as ‘Hoover’ is to vacuuming and ‘Sellotape’ is to adhesive tape. The basic principle of all is that the stripped-out thread is replaced by enlarging the hole, tapping it oversize and fitting an insert with the same size and pitch as before. It’s a far more elegant solution than the once-popular bodge of tapping a hole out to take a larger fastener.
Another benefit of a threaded insert is that it often offers a much stronger thread than was there before, particularly when going into aluminium.
However they do have to be fitted correctly for the fastener to work as desired. If the hole isn’t properly tapped out, the insert can become thread-bound or offer too small a diameter for the fastener to go into. It must also be absolutely concentric with the original hole or the stud or fastener won’t line up with the components it holds together.
Here’s how to do it right.
Tools for the job
Cutting compound. Hammer. Drill. Tap. Thread insert tool. Tang removal tool. Tap
Pete O’dell: a champion of thread inserts and liberal thinking Only serious looking tools for a serious job