Lesson's From LIfe's Workbench - Working with Helical Inserts

Ahh. The helical insert.   If you've run into a mangled thread, there's a good chance you've had to use one.  Most likely it's come in the form of a tightly wound, diamond shaped wire which forms the insert.

The common helical-insert.
By The original uploader was Boellhoff at German Wikipedia - Transferred from de.wikipedia to Commons by MichaelFrey using CommonsHelper., Attribution, https://commons.wikimedia.org/w/index.php?curid=7363606

You may also know them as "Heli-Coil" inserts.  Heli-Coil is actually the name of a specific brand of helical inserts, but the names have become interchangeable, much like Teflon (PTFE), Kleelex (facial tissue), and Inconel 718 (Nickel 718).

Many of us have used them to repair stripped threads, they can also be used in softer materials, such as aluminum, to create a more durable thread.

A helical- insert used to repair a thread.

But like any fastener, they need to be placed into a threaded hole, which requires drills to tap holes, and depths for threads

Luckily, I found a great website that has the recommended taps, and hole diameters for helical inserts.

Our friends at Noble Aerospace have provided a recommended drill size chart, and a tap chart for both Imperial and Metric threads.

It's a nice resource if you're using helical inserts in your next design!

How Noble of them indeed! 

Additional photo credits:

photo credit: rustyheaps Repairing exhaust manifold, XK engine via photopin (license)