Testing Threaded Inserts

by R.M. Mottola

Originally published in American Lutherie #101, 2010



Threaded inserts are used in bolt-on acoustic guitar necks, in the style of neck joint popularized by Taylor guitars. An example of a butt-joint neck heel with threaded inserts is shown in Photo 1. I have posted instructions for constructing this style of neck joint on my lutherie info website and not long ago received an e‑mail message from someone taking me to task for the type of threaded inserts specified there. For years I have used self-tapping machine screw threaded inserts and have had good success. But the writer pointed out that these inserts were “not for wood” and so I thought a test of these and other types of threaded inserts would be an appropriate thing to do. There may be better inserts than the ones I was using, and testing is the only way to find out. What I wanted to discover was how strong the hold of the insert was on the wood into which it is inserted.