Ran across this and thought that some folks might find interesting: Different thread repair inserts tested in 6061 aluminum.
Aluminum is not Cast Iron, but the testing methodology was pretty good.
I was not surprised at the results (consistent with my experience) and personally will continue to use the product that I have used in the past with great success (no failures)
Your mileage may vary...
Scott very informative . Thanks for posting. Cheers pete
you're most welcome. I'm glad you found it informative...I did, too.
Good stuff Scott, thanks.
The first part showing the inserts being pulled, got that. The 2ed part lost me and stopped watching at the helicoil. Not knowing how the device works that was shown in first part of that segment and not being able to see the whole thing, didn't have a clue what and how done. Other then that informative info.
Oh I can add, I replicated part of the test, pulling threads on the 6061 that I am using on the adapter plate. While unofficial, the threads started getting soft about 65-70 ft pounds with a 7/16 coarse threaded bolt. I think the tap was rated for about 75% thread but would need to check more.
the % thread would be related to the drill size, not the tap. An awful lot of folks just use whatever guide they have (usually what comes with the drill set or tap), but for different materials, different % threads are desirable, as often an increase in % thread vs. higher tap breakage is a losing proposition and very little extra strength is gained by increasing % thread depth. For aluminum, you're right on at 75% thread. For tougher materials you can drop the % thread and lose very little strength while preserving your tools.