Guitar and Bass Neck Threaded Inserts

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BeeTL
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Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Sun Dec 07, 2014 3:52 pm

There are a lot of approaches to attaching a “bolt-on” neck to a guitar or bass body, and the traditional method involves using #8 wood screws.

While that method isn’t bad, I have found it to be somewhat lacking as the neck mounting holes can become stripped over time.

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.

Image

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:

Image

- 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 329-008 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):

Image

Image

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:

Image

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

Image

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

Image

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:
Image

Image
Last edited by BeeTL on Mon Oct 16, 2017 3:25 am, edited 2 times in total.
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Re: Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Sun Dec 07, 2014 4:08 pm

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

Image
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Re: Guitar and Bass Neck Threaded Inserts

Post by kdanie » Sun Dec 07, 2014 7:12 pm

I also prefer using steel inserts but I've never used that kit. It works well with a neck plate too. I think it adds to sustain and tone while making it easier to assemble/disassemble the neck joint and makes it easy to get the joint really tight.

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Re: Guitar and Bass Neck Threaded Inserts

Post by Stereordinary » Sun Dec 07, 2014 7:30 pm

I've tried a few different inserts, and ultimately decided that the hardware and method suggested here and by Mr. Johnson is the best way to go. Some of those brass inserts can just really fall apart. I'm not a big fan of that red "epoxy" adhesive that comes on the EZ-Lok brand of inserts though. So I usually take a wire bristle brush to them to remove that crud, then just use CA glue on them.
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Re: Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Sun Dec 07, 2014 7:38 pm

Stereordinary wrote:I've tried a few different inserts, and ultimately decided that the hardware and method suggested here and by Mr. Johnson is the best way to go. Some of those brass inserts can just really fall apart. I'm not a big fan of that red "epoxy" adhesive that comes on the EZ-Lok brand of inserts though. So I usually take a wire bristle brush to them to remove that crud, then just use CA glue on them.
Good to know...I was reluctant to modify the system on the first one.



By the way, most of the photos are from others' builds except the two with the wood background.
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Re: Guitar and Bass Neck Threaded Inserts

Post by ARAMP1 » Mon Dec 08, 2014 4:01 am

Very nice write-up, thanks for doing it. I'm planning on doing this on my next build with a graphite neck.

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Re: Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Mon Dec 08, 2014 4:51 pm

Thanks!

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.
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Re: Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Sun Oct 15, 2017 6:04 am

A couple of updates.

First, I'm not sure if Chet offers these kits any more, but it doesn't hurt to check with him if you're interested.

I found that shipping really drove up the cost on small quantities of the EZ-Lok 329-008 inserts, so if offered, a kit could make sense if you can't source parts locally.

Second, I found it to be easier and more precise to locate the "pilot hole" after the hole for the insert has been drilled and tapped.

In the lower left hand corner of the photo, note that the inserts are painted red on the edge.

Those are "sacrificial" inserts that I use to locate the pilot hole after the fact.

Once the insert is in place and the CA adhesive is dry, I use an 8-32 tap to chase the threads of the insert and tap the wood walls of the pilot hole beneath it.

This ensures that the mounting bolt seats properly all the way into the wood and doesn't exert any back-pressure on the insert.

Finally, I follow Paul's advice above and clean the red adhesive off with denatured alcohol and a toothbrush.

Image
Last edited by BeeTL on Mon Jun 10, 2019 11:47 am, edited 2 times in total.
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Re: Guitar and Bass Neck Threaded Inserts

Post by mbene085 » Sun Oct 15, 2017 9:56 am

This looks like a great idea - but I have a question. If you choose to add a shim to the neck pocket (say, because you swap the bridge for a design that is lower or higher profile), would the metal threads of the insert become stripped since you'd be trying to insert the screw at, say, a 1 degree angle? Or would that be within tolerance for the insert?

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Re: Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Sun Oct 15, 2017 11:43 am

It's absolutely within the tolerance of the insert, especially if you ream out the mounting holes in the body just a little bit.

I have used these with shims on more than a few occasions.
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Re: Guitar and Bass Neck Threaded Inserts

Post by mbene085 » Sun Oct 15, 2017 3:39 pm

BeeTL wrote:It's absolutely within the tolerance of the insert, especially if you ream out the mounting holes in the body just a little bit.

I have used these with shims on more than a few occasions.
Wow, that's great. Can't think of a single reason why this isn't a superior way of doing this, then!

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Re: Guitar and Bass Neck Threaded Inserts

Post by Rgand » Mon Oct 16, 2017 10:45 pm

I have often thought about doing inserts. Thanks for this thread, it pushes me in that direction.

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Re: Guitar and Bass Neck Threaded Inserts

Post by hpr_hpr » Tue Oct 17, 2017 11:01 am

mbene085 wrote:Wow, that's great. Can't think of a single reason why this isn't a superior way of doing this, then!
it IS a superior way (larger diameter = more 'contact' = much more force needed to rip it out of the wood & it doesn't 'wear' noticeably even with repeated 'use'), but it adds cost (part & time to install) and wood screws are good enough in hard woods like maple thus a large scale manufacturer will not bother . . . .

I like the tapping though, hadn't thought of that . . . . should make fitting the insert easier.

re: locating the pilot hole using a sacrificial insert . . . I actually use a nylon brushing, it's easier on the drill bit. And I actually do the same for locating the holes (either for wood screws or for inserts) in the neck. I dill the holes in the body, fit the neck and then put nylon brushings in the holes and drill pilot holes for the neck screw (or insert) locations in the neck. If the neck pocket is correctly sized to the heel this makes for 0 error in the location of the holes in relation to the holes in the body as the pilot holes are exactly in the center of the holes drilled in the body.
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Re: Guitar and Bass Neck Threaded Inserts

Post by BeeTL » Sat Oct 21, 2017 4:52 am

hpr_hpr wrote:
Tue Oct 17, 2017 11:01 am
mbene085 wrote:Wow, that's great. Can't think of a single reason why this isn't a superior way of doing this, then!
it IS a superior way (larger diameter = more 'contact' = much more force needed to rip it out of the wood & it doesn't 'wear' noticeably even with repeated 'use'), but it adds cost (part & time to install) and wood screws are good enough in hard woods like maple thus a large scale manufacturer will not bother . . . .

I like the tapping though, hadn't thought of that . . . . should make fitting the insert easier.

re: locating the pilot hole using a sacrificial insert . . . I actually use a nylon brushing, it's easier on the drill bit. And I actually do the same for locating the holes (either for wood screws or for inserts) in the neck. I dill the holes in the body, fit the neck and then put nylon brushings in the holes and drill pilot holes for the neck screw (or insert) locations in the neck. If the neck pocket is correctly sized to the heel this makes for 0 error in the location of the holes in relation to the holes in the body as the pilot holes are exactly in the center of the holes drilled in the body.
The nylon bushing idea is intriguing.

Do you buy them or fabricate them yourself?

I use the same set over and over, so after a couple of uses the inserts were smooth on the inside.

The drill bit doesn't touch the insert, it's just a centering guide.

On the inserts themselves, it looks like Bill Crook uses the same EZ-Lok 329-008.

https://www.facebook.com/bill.crook.777 ... 2867975297
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Re: Guitar and Bass Neck Threaded Inserts

Post by marqueemoon » Sat Oct 21, 2017 8:33 am

I've also been intrigued by this for awhile. Rock Rabbit has a pretty detailed video of the process with their kits. I like the tapping idea.

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