Guitar and Bass Neck Threaded Inserts

[BTL]

There are a lot of ways to attach a "bolt-on" neck to a guitar or bass body, and the traditional method involves using #8 wood screws.

While not necessarily bad, I have found wood screws to be somewhat lacking over the years as the neck mounting holes can become stripped and loose with repeated dis-assembly.

When I went looking for a better solution I found a number of different approaches to solving the problem, most of which involved various types of EZ-LOK inserts for wood or metal.



After reviewing the merits each, I decided to go with Chet Johnson's system because it blends a variety of simple tools, supplies and materials into an elegantly simple solution that most players and builders can perfect easily on the first try with just a little skill and patience.

I also added one little "twist" to Chet's approach because my bodies have sculpted heels and each bolt will vary from the next as far as how deeply it penetrates into the neck.

Here are the supplies I use, including the instructions as provided by Chet in his kits:



- 5/16-18 Tap (kit)
- 8-32 socket head bolt (kit)
- 9/64" Allen wrench (kit)
- 8-32 oval-head stainless steel bolts, 1.25" and 1.5" (kit)
- EZ Lock inserts, 4 (kit)
- 1/8" twist drill (mine)
- 1/4" Forstner bit (mine)
- Harbor Freight Tap Handle (mine)
- Wood handled awl for marking the neck bolt holes (mine)

The kit Chet offers comes as shown (bit and tap optional if needed):





I mark each bolt hole on the back of the neck with the awl while the neck is clamped in place. 

Next, I mark the 1/8" bit with blue tape to the maximum depth the neck will safely allow and drill a pilot hole.

This will allow the bolts to extend past the insert and "self-tap" into the neck wood, eliminating any potential "back pressure" a bolt could apply on the insert if it bottoms out within the neck.

This is likely not a concern for a standard neck with a plate and uniform heel, but I use bushing inserts and have sculpted heels on my builds, so the bolt depths are not uniform.

This is my "little twist" on Chet's system.

Next, I use the 1/4" Forstner bit marked with blue tape to allow the insert to sit just below the surface of the neck.

A standard twist drill bit is shown here:



I use a drill press, but a steady-handed person could get away using a hand drill with a twist bit:



Once the 1/4" holes are drilled and the sawdust is blown out, the holes are TAPPED with the 5/16-18 tap.



Tapping  the hard maple neck and using hardened steel inserts designed for metal vs. brass inserts for wood is unique to Chet's approach.

Everything I've read and experienced firsthand leads me to believe this results in a more consistent and predictable result compared to the "knife-thread" brass inserts designed for softer woods.

Another of Chet's innovations is to use a hex bolt to drive the insert into the tapped hole.

This results in a clean and consistent installation vs. using a flat-head screwdrived as many would be inclined to do.

The installed inserts look like this:




The finished result looks completely "stock", but is significantly more durable and serviceable over the life of the instrument.

Most of the photos are of others' previous builds with Chet's system.

Here's my first bass using the inserts:

[BTL]

I went ahead and bought 10 kits directly from Chet to get me started because I wanted his detailed instructions and also to give credit where it's due.

For only doing a neck or two, I think his kits are the way to go, if only because of the consolidated shipping costs for the various parts if sourced from multiple locations.

If interested, Chet can be contacted directly at cjohnsoncustom@yahoo.com.

[Pilgrim]

Threading the drilled hole with a tap is a little feature I hadn't thought of.  That would be a nice way to prevent chipping and enlarging the hole when the insert is turned in.

[BTL]

Threading the drilled hole with a tap is a little feature I hadn't thought of.  That would be a nice way to prevent chipping and enlarging the hole when the insert is turned in.

Using metal vs. wood inserts, threading the hole with a tap, and driving the insert in with an allen bolt instead of a screwdriver are all things I would not have thought of on my own.

Learning those ideas and having written instructions with photos made getting the kits directly from Chet instead of driving all over town to source the parts a no-brainer.

[drbassman]

The key to making inserts work is drilling a hole large enough the insert won't crack the surrounding wood when you screw it in and tight enough to not work free over time.  I know, I've done both things wrong!  Nice job!  Correct installation is the key.

[BTL]

The key to making inserts work is drilling a hole large enough the insert won't crack the surrounding wood when you screw it in and tight enough to not work free over time.  I know, I've done both things wrong!  Nice job!  Correct installation is the key.

Agreed.

I was surprised at how beautifully the tap cut the threads in the maple neck and how firmly the steel inserts grab.

[Highlander]

Nice idea... engineering sources should also be considered... inserts aren't that uncommon and I used them back in my aviation days where a fixing required to be re-secured in an oversize hole... "helicoil insert" was one trade-name we used on Boeings... using a hex-key is a wise move to avoid strain on the fitting - virtually no "down-pressure".

[BTL]

Yes, it looks like EZ-LOK makes a heli-coil style insert.

Overall, a very clever fix.