DIY luthier tools
Build your
own neck jig.
Commercial neck jigs cost more than most people's first build. This is how to make one that does the same job for a fraction of the money.
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What a neck jig actually does
A neck under string tension isn't the same shape as a neck with the strings off. It bows forward, slightly, and that's the shape it will be in when somebody plays it.
So if you level frets with the strings removed, you're levelling a neck in a shape it never occupies in use. A neck jig holds the neck in its undertension shape while the strings are off, so the levelling you do is the levelling that matters.
The trick that makes it work: set the guitar up strung and at pitch, bring the supports up to touch, and zero the dial indicators. Then slacken the strings, the dials will move as the neck relaxes. Adjust the supports until the dials read zero again. The neck is now mechanically held exactly where string tension had it, and you have full access to the frets.
Cost, versus buying one
A commercial neck jig runs into several hundred dollars. This one is mostly scrap.
| Part | Cost | Notes |
|---|---|---|
| Dial indicators × 2 to 3 | The only real expense | Harbor Freight or similar. The only precision parts. |
| Locking handles × 4 | Cheap | Noticeably cheaper online than in a local store. Thumb screws work too. |
| Steel weld nuts × 4 | Pennies | Receive the handle screws |
| Rubber stoppers × 4 | Pennies | Dense ones. These touch the neck. |
| Steel rod | Cheap | Home Depot. Cut into posts. |
| Turnbuckle | Cheap | See the note below |
| Ratchet tie down strap | Scrap | Most people with a truck have a spare |
| Camera strap | Scrap | Holds the headstock end |
| Maple base, guides, blocks | Scrap | Dense, tight grained, takes screws |
| Screws | Pennies | #4 × 3/4″ |
The part with no name here is a turnbuckle. Two threaded eyes in a central body, turn the body and both draw in together, adding tension. Sold in any hardware store and online under that name, usually in the rigging or chain section. That's the part that tensions the headstock strap.
The numbers, in one place
| Dimension | Figure |
|---|---|
| Post rod hole | 5/16″ |
| Weld nut hole | 7/16″ |
| Post length | 5″. About 2″ embedded, 3″ of travel above |
| Post spacing from the nut | 1 1/2″, then 5 1/2″ intervals |
| Number of posts | 3 for guitar, 4 to also cover bass |
| Mounting screws | #4 × 3/4″ |
| Slide guides | ~1/16″ taller than the carrier |
| Carrier lock holes | 1″, 2″, 3″ |
| Thumb screw pressure block | 1/4″ × 1/4″ |
Laying out the posts
Draw a centerline down the base. The quickest way is the old trick of hooking a finger over the edge as a fence, locking your grip, and dragging your hand the length of the board with a pencil.
Then lay an actual neck on it and work out where it wants support. The nut position is the reference everything else is measured from.
The spacing that came out of this: one post 1 1/2″ from the nut, then further posts at 5 1/2″ intervals. Three covers a guitar. A fourth extends the same pattern to cover a bass.
Check your layout against both a guitar neck and a bass neck before drilling, it costs nothing at this stage and the holes are permanent.
Cutting the posts
Steel rod needs a Dremel with a metal cut off wheel. Aluminum can go on the bandsaw.
You rarely need to cut all the way through steel. Cut about halfway and snap it off, faster, and easier on the cut off wheel.
Work out the length from the travel you need. Deepest support in this build is 5 1/2″, so 4″ posts would do and 5″ gives margin. With about 2″ embedded in the base, that leaves 3″ of usable rise.
Drilling the rubber stoppers
The stoppers cap the posts and are what actually touches the neck. Dense enough to support, soft enough not to mark.
Drill them 5/16″ to accept the rod.
Go slowly and pull out often to clear the bit. Rubber grabs, heats and tears. And don't go all the way through. The post needs to stop inside the stopper, not poke out the top where it'll dent a fretboard.
Fitting the weld nuts
Weld nuts are designed to be spot welded, but they've got flange holes you can screw through, or you can simply epoxy them in. Drill 7/16″ for them.
Assembly with five minute epoxy:
- Stoppers: a small amount of epoxy on the tip of the post only. The rubber acts as a squeegee as it goes on, so more just makes a mess.
- Weld nuts: apply so the epoxy squeezes upward, out of the hole. Not down into it, where it would foul the thread. Let it come up through the flange holes and trim it off once set.
Then #4 × 3/4″ screws through the flange.
Don't overtighten these screws. Many will simply shear off flush, which is a genuinely irritating thing to drill out. Deck screws take real torque; drywall, zinc and especially brass screws snap easily.
If your nut has no flange holes
Two workarounds:
- Drive two or three large headed screws right alongside the nut so their heads trap it in place
- Or use a plain hex nut: cut a matching recess with a Forstner bit, drop it in, epoxy it, and add screws beside it
Test before you go further
Two checks:
- Crank the handle hard. The nut shouldn't pull out. You should be able to lift the whole jig by the handle.
- Hit the top of the post. It mustn't move down.
Why the second test matters: you'll be hammering frets in with the neck sitting on these. A post that gives under a hammer blow lets the neck move and leaves a mark in it, and a dent in a nearly finished neck is a bad way to find out your jig has play in it.
The dial indicator carriers
The dials need to be removable and repositionable. Two stations for a guitar, moved along for a bass, and potentially two side by side for something short like a ukulele. Build them as modules that drop into any station.
Method:
- Cut a slot in the base for the carrier, 2 3/4″ wide here
- Rout with a template and a bearing guided bit, in increments
- Once the cut is established, remove the template and continue against the cut itself
- Make one, then use it as the pattern for the rest
The slides
Glue wooden guides either side so the carrier can only move up and down. Make the guides about 1/16″ taller than the carrier: tight side to side, with a little leniency the other way.
Wood moves with the seasons, and these will loosen and tighten over time. That's acceptable here, what's not acceptable is vertical play.
A measuring device has to be rigidly mounted. A little side to side movement is liveable. Any up and down movement goes straight into your readings and makes the whole jig useless. Fix the dials down hard, and choose a screw with a head big enough to hold, but short enough that it doesn't come through the other side.
Drill a clearance hole so the dial plunger can pass down through the base to reach the neck, then drill lock holes at 1″, 2″ and 3″ through the top into the slide so each carrier can be pinned at height.
The body sled
A ratchet tie down strap holds the body down. Mount it solidly instead of using quick release fittings, the more rigid the whole assembly, the more trustworthy your readings.
- Cut a notch for the strap end and staple it down
- Whatever you fit on one side, fit on the other. An asymmetric sled pulls the guitar sideways as you tighten it
- Pad where the ratchet mechanism contacts the body. Leather, cardboard or a rag
- Deck screws lock the sled at the right position, and come out when you need to slide it for a bass
A nice detail: the sled extension here is Spanish cedar, chosen deliberately because it's soft. If anything is going to give, better it's the jig than the guitar sitting on it.
The headstock end
This is the fiddliest part of the build. The nut area needs to be held down firmly and adjustably, without marking anything.
- Forstner a hole at the nut position, sized to clear the strap, and open it out at the back with a router
- Knock two short rods through crossways near the front of that opening
- Run a camera strap through, passing outside both rods, and staple the end underneath
- Fit a thumb screw that presses on a small 1/4″ × 1/4″ wood block, that block is what pulls the strap tight
- Mount the turnbuckle in a block of wood with epoxy so it stands upright, giving you a second adjustment point
Pad anywhere the hardware touches finish. Cardboard is fine on a fully cured finish with a good roundover; leather is safer on anything delicate.
Expect to fit the strap, pull it back out and do it again. It's an awkward assembly and there's no elegant way through it.
Using it
The sequence matters. Getting it out of order gives you a neck held in the wrong shape.
- Fit the guitar and ratchet the body down
- Release all the posts so nothing is touching the neck yet
- Lay a notched straightedge on the neck and look for light underneath, a light source behind it makes this much easier to read
- Adjust the truss rod until the neck is as flat as you can get it. You're looking for the happy medium: relieve one area and another will grow. Within a paper's thickness is a good result
- Bring the posts up until they're snug. Snug, not pushing, you're supporting the neck, not moving it
- Zero the dial indicators
- Tighten the headstock strap
- Now slacken or remove the strings. The dials will move
- Adjust post and strap tension until the dials return to zero
- Level the frets
Step 5 is the one to be careful about. Pushing the posts up hard doesn't support the neck, it bends it, and then you level a shape the guitar will never be in again. Snug is the whole instruction.
Two improvements worth building in
- Grind a flat on each rod where the locking screw contacts it. A screw point on a round rod slips; on a flat it bites and holds far better.
- Put springs in the post holes so each post is always pushed upward. Drop a neck in and the posts find it automatically instead of you winding each one up by hand. My previous jig had these, and they're worth the extra effort.
On building your own tools
This is the third neck jig I've built. The previous one worked for years. The reason for a new one wasn't that the old one failed, it was that after years of using it you know exactly what you'd do differently.
That's the real argument for building your own: not just the money, but that the second one fits your work better than anything you could have bought, and the third fits better still.
None of this has to look good. It has to be rigid, repeatable and not mark a guitar. Use scrap, use what your local hardware store happens to stock, and look at how other builders have solved the same problems before committing to a layout. There are many valid approaches to holding a neck, particularly at the nut end.
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Last reviewed: August 2026