Recent content by Shannon Boal

Looking at the original photo, I count eight or nine threads pulled out. Nine threads at 1.0 mm, makes one and one half diameters engaged. In steel, that woulda been OK, in aluminum the longer the better.

So, you could get two diameters (12mm) of threads engaged, and be quite a bit stronger than the original threads.....which lasted a long time.

Part of the pullout problem is depth of the threads. (Thread depth rule of thumb; one and one-half diameters, but more with aluminum). I drill the hole full depth plus all I can get at the helicoil tap drill size. Then I tap it and follow up with a helicoil tap with the end ground off (homebrew...