My Fretting Process; Installing, Leveling, Crowning & Polishing

[Bruce Johnson]

We've had many threads here about the fretting process, covering people's different techniques, problems, and tradeoffs. I just fretted one of my Scroll Basses last week, and photographed all the steps. My process has evolved over the years. This is the current way I do it.

Here's the neck. It's one of my Walnut AMB-2 Scroll Basses; a walnut neck with a Macassar ebony fingerboard.

The fingerboard is radiused to 7.25" and slotted, then level sanded with 220, and fine-sanded with 400, grey Scotchbrite and white Scotchbrite. I check the depths of all the slots with a little gauge. The edges of the fingerboard get a small bevel. You've probably seen my other threads about how I do all that.

Two coats of Stew-Mac Fingerboard Oil, allowed to sink in, and the excess wiped off.....

After curing overnight, the surface is buffed on this ebony-only cotton buffing wheel.

Which brings it to a nice semi-gloss sheen like this. My preference for this model bass; it fits with the "1940's" style. I carefully clean out the slots with a hook tool.

That's the preparation of the fingerboard. It's all sealed up and in nearly-finished condition.

 

[Bruce Johnson]

Preparing the frets:

These days, I use stainless fretwire on all my basses, Jescar's 37080S. That's the small, low classic-size fret wire. I buy it in a 1 lb roll, and run the whole roll through my fret roller to bring it to 6" radius, which makes a 12" diameter roll.

I use this little machine to snip off a whole set of 21 frets (20 + Zero Fret) and put them in the numbered holes in the wood block.

This machine cuts each fret to right length, stopping them against the rotating cam. I covered this machine on its own thread a while back.

Then each fret gets its tang ground back a small amount in my little Fret Tang Grinder. It also has its own thread, if you are curious.

Installing the frets:

The secret sauce: I pour a spoonful of LMI glue into a plastic cup, and mix in a drop of black pigment.......

Then pour it into a plastic industrial syringe.......

Ready to install. There's all the tools. The neck is mounted securely in the holding fixture.

I install the frets in groups of 5 at a time. I use the syringe to lay a small bead of the black glue in 5 slots, then let it sit for 2-3 minutes to sink into the slots.

Then I set each fret in place, getting the ends of the tang started in the slot, and lightly tap the ends down with a rubber dead-blow hammer....

Meanwhile, I've rolled over my arbor press and plugged the 7 1/4" radius plastic caul onto the ram. And set the entire holding fixture on the table. Doing 5 frets at a time.

I use the press to seat each fret fully down against the surface of the fingerboard. It doesn't take much force, maybe 50 lbs max. This arbor press is obviously hugely oversized for the job. But it has the large throat to fit the whole fixture, and it's comfortable to use.

After the group of 5 frets are pressed in, I check them carefully to make sure they are all seated in the center. Light taps with a hammer and plastic block if needed.

Pressing the frets in will usually squeeze a little bit of the black glue out the ends. I tip the neck sideways and add an extra drop of black glue to the end of each slot to make sure they are filled.

When all the frets are in, I let the neck sit overnight to get the glue fully cured.

 

[Gilmourisgod]

Always fascinating to see your process and dedicated machines, that fret tang grinder is particularly slick, I’m still doing it with a Dremel cutoff tool and needle files, takes hours to do a full set of frets. I’ve done a couple basses using CA glue for the frets, what will be your substitute once the LMI glue runs out? Fish glue?

 

[TheReceder]

If I was your neighbor you'd probably have to file a restraining order to keep me from watching you work.

Nice job!

 

[ProbablyTooLoud]

Bruce I'm not a luthier and it’s best for me to let pros work on my basses for most stuff, but I just wanted to say the generosity with your time and the effort you put into sharing your knowledge here is really amazing.

 

[Level5wizard]

Thank you this is very helpful. With a maple fingerboard. Would you sand to 400 then polyurethane?

 

[CryingBass]

Very impressive Bruce. Thanks for sharing.

 

[Hurricane Jimmie]

So Anyway, thanks for posting your process. So much knowledge and experience on display.
Just stumbled across the Filmore Gazette article.
Love and Luck my friend.

 

[pbass888]

Thanks again for contributing so positively to the talkbass community Bruce!

 

[Cleezmo]

As someone who has anything other than string changes done by a pro, I really appreciate reading these types of threads where said pros are showing their methods. Always cool to see all the little details that go into making something Really Good.

 

[joeLowB]

So impressed! Love all the special tools!

Thanks for taking the time to share so clearly!

 

[MaxSpinrun]

As others have said, information you share reflects you vast experience and knowledge! I appreciate you sharing because I always learn something even if I never actually get to that level of execution. Thanks again.

 

[Bruce Johnson]

Thanks, everyone! Yep, this is what I do here in my Secret Underground Lab, and on Luthier's Corner. I've been writing these threads for about 12 years. I'm mostly trying to help out the hobbyist Luthiers to solve the problems of building basses. But you non-Luthiers are welcome to read along for your education and entertainment.

Here are links to some of my threads about particular machines and processes shown here:

The fixture for radiusing the fingerboard in my Pin Router:

Post in thread 'Pin Routers: The Old-School Production Workhorses'

Jul 16, 2025

Getting back to the Fingerboard Radiusing Fixture, which I showed a few posts ago;

I built it with 3 1/2" radius blocks and a cradle to hold that little electric upright neck. A prototype project. I tested the fixture on that neck, and it worked well. Now I'm going to fit it up with 4" radius and 7.25" radius block sets, and a cradle made to hold my Scroll Bass necks. The real job that the fixture was designed for. Those are the two fingerboard radiuses that I use on all my basses.

Making up the radius block sets. The first step, as usual, is to pick out a couple of...

• Bruce Johnson

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My Fret Slotting Saw:

Thread 'Fret Slotting Saw Upgrade: Better Indexing Mechanism'

Mar 28, 2024

Most of you have seen my Fret Slotting Saw here on Luthier's Corner. I originally built it over 30 years ago(!!) and it has slotted several thousand necks and fingerboards. For my own basses and many other Luthiers.

Well, it's time to do some upgrades on the old machine. In particular, I've come up with a new Indexing Mechanism. That's the mechanical parts that bring the neck-holding sled to accurate positions for locations of the slots. It has to be solid, accurate and repeatable.

This new design I've come up with is looking good. It's faster operating and almost fool-proof, and very...

• Bruce Johnson
• Replies: 46
• Forum: Luthier's Corner

• 

My Fret Cutoff Shear:

Thread 'Fret Cutoff Rig'

Dec 28, 2018

Here's another little specialty machine that I just completed. Keith and I are now doing more of our fret jobs in the binding style, which requires pre-cutting the fret wire pieces to pretty close to the final length, then notching the tangs.

You may have seen my thread about the Fret Tang Grinder that I built:

Fret Tang Grinding Machine

The Tang Grinder solved the problem of notching the tangs, but it was still taking us way too long to snip the fretwire to accurate lengths for each fret position. So, I decided to make up a special machine/fixture to do this.

The heart of the...

• Bruce Johnson
• Replies: 2
• Forum: Luthier's Corner

• 

My Fret Tang Grinding Machine

Thread 'Fret Tang Grinding Machine'

Sep 24, 2018

On a few other threads, we've talked about working with binding on the sides of fingerboards, and the problem of notching the tangs at the ends of the frets, so they overlap the binding. There are several pliers-type tang notching tools available, but we've never really liked them. Keith has one of the Stew-Mac tools. It kind of works, but it's not consistent, and the fret ends often need some additional hand filing. And they are painful on the hands to use. All of us here in the Lab are doing more of these bound fingerboards, and we need a better way to notch frets.

So, I decided to make...

• Bruce Johnson
• Replies: 27
• Forum: Luthier's Corner

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My Stone Bars for leveling the frets:

Thread 'Special Tools: Stone Bar For Leveling Frets'

Aug 8, 2017

Here's a special Luthier tool that I'm experimenting with.

I'm not really interested in making or selling these. I built this for my own use, and I may make up a few more for the other guys here in the Lab. Any of you are welcome to grab the basic idea and make your own.

I like leveling my frets using a flat sharpening stone. There are various reasons, but mostly because the stone is very precise, lasts approximately forever, and it minimizes scratches on the frets. I particularly like the stone method on stainless frets, which are what I mostly use these days. My favorite stone is an 8"...

• Bruce Johnson
• frets special tools
• Replies: 34
• Forum: Luthier's Corner

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[Bruce Johnson]

what will be your substitute once the LMI glue runs out?

Hello Alex;

At the moment the leading substitute for the LMI Yellow Instrument Maker's Glue is Gorilla Wood Glue.

Gorilla Wood Glue; 8 Ounce Bottle; Natural Wood Color; (Pack of 1) - Amazon.com

Gorilla Wood Glue; 8 Ounce Bottle; Natural Wood Color; (Pack of 1) - Amazon.com

www.amazon.com

This is not the original polyurethane Gorilla Glue! The Gorilla Wood Glue is similar to Titebond 1, with some improvements. I haven't done a lot of testing with it, but it appears to be fairly close to the LMI glue. They also sell Gorilla Ultimate Wood Glue, which is more like Titebond 2.

 

[Bruce Johnson]

Thank you this is very helpful. With a maple fingerboard. Would you sand to 400 then polyurethane?

I don't use maple fingerboards on my basses, but if I did, yes, I'd sand to 400 level and spray on several coats of polyurethane. Level sand the surface and buff it up just like the finish on the body. Then install the frets.

 

[Bruce Johnson]

Continuing on with the process:

Shaping the ends of the frets:

Because I've already pre-cut the frets to length before installing them, the ends are about even with the edge of the fingerboard. So, I don't have to do any trimming off of the ends with clippers.

First, I file the bevels on the ends using a long flat "safed" file. I hold the file angled like this, and make long strokes down the length of the edge of the fingerboard. I want the size and angle of the bevels to be the same on all the frets. Then, I tip the file up vertically and run it down the side of the fingerboard, to take off any ends of frets that might be sticking out.

This is what the Safed file looks like. It's a 10" Smooth fine-tooth flat file. On one side, I've ground the edges to round them off and take off the teeth. This keeps the edges from digging in and cutting grooves in the fingerboard, while the center is cutting the frets.

After the bevels are filed to size and shape, I go over them with my Norton Medium Oilstone. This takes out the file marks and brings them up to about an 800 grit level shine.

Not a great picture, but this is how the bevels are shaped. They are D-shaped, full width at the bottom, leaned back about 45 degrees, flush with the lightly beveled edge of the fingerboard.

Next is the Combi-Flap Wheel treatment. I showed these on that thread about rounding fret ends. It's a flap-wheel style sanding drum with alternating layers of cloth-back sandpaper and Scotchbrite. It's a great tool for gently rounding off and blending the ends of the frets and the edge of the fingerboard all at the same time. Held like this, I bring it slowly down the edge of the fingerboard in this direction......

Then go back the other way held like this. This rounds off both sides of the ends of each fret.....on one side of the neck.

Turn the neck around and do the same two passes down the other side.

After the Combi-Flap wheel, I go back over the ends of the frets with 400 paper on a soft rubber block. This finishes up the rounding and blending. Holding the block diagonally like this keeps the paper from catching on the ends of the frets and ripping.

Next up: Leveling the frets!

 

[Bruce Johnson]

Leveling the frets:

The first step, before leveling the frets, is to check the tightness of the truss rod. I back it off, then tighten it up partway, enough that I can see the neck beginning to bend back. This is an important step in making the neck stable. With the truss rod partially tightened like this, the fingerboard and frets should be pretty close to flat, because I also cut the radius on the fingerboard with the truss rod partially tightened.

The Sharpie Trick: A critical part of fret leveling. I lightly drag the side of the tip of a Sharpie-type marker down each fret, leaving a line of bluish ink. All the frets. I like the Milwaukee brand markers better than genuine Sharpies for this. Their ink sticks better to metal.

Doing the leveling with one of my Stone Beams. This is an aluminum bar with a row of grinding stones epoxied along the bottom edge. I covered them on that other thread.

I slide it in a straight line down the neck, back and forth in about a 6" stroke length. It's 18" long, which is a good working length for a bass neck. I stop short of the Zero Fret, only grinding frets 1-20. Here I'm taking a picture, but I use it holding it with two hands near the ends. Not really pushing down, mostly letting the weight of the bar do the work. I slide it back and forth, approximately following the string paths and blending between them.

If the fingerboard is cut straight and the frets are all seated carefully, it doesn't take long. Not much metal being removed. This neck only took a few minutes to level.

Here's where the Sharpie ink comes in. After every few strokes of the Stone Beam, I lift it off and look at the blue ink. Any frets where the stones are contacting and grinding will have a narrow silver stripe down through the blue ink. Those frets are the high ones and are being ground down. Any frets where the blue ink doesn't have a silver line are still lower than the others.

When they all have silver lines, the frets are level. Within about 0.001". That's the beauty of using long stones and blue ink. It's a classic method of leveling and flattening machine surfaces to high accuracy from 150 years ago.

In this picture, I'm almost done with the leveling. You can see that the 18th and 19th frets still have a few patches of untouched blue ink. About two more strokes and they were gone. On this neck, the 15th fret was the high one, for some reason. It was maybe 0.003" higher than the others, not quite as well seated. So it wound up with a wider silver stripe than the others around it. That's what the leveling process is for, to find the high frets and bring them all down to equal.

With the leveling finished, I use this dial indicator gauge to check the height of the Zero fret versus frets 1-3. I want it about 0.008"-0.010" higher. It came out right on the first try.

The final step of the leveling process is to slide the Medium Oilstone crosswise on all the frets. This makes the scratches on the top of the frets finer grit and going cross-wise. The little silver lines are shiny.

Next up: Crowning and polishing.

 

[Blues Daddy]

Fascinating !

. . . and so many bespoke tools ! Looking forward to the next chapters.

 

[Bruce Johnson]

Finishing up the frets: Crowning and Polishing

My favorite crowning file for these small stainless frets is the classic StewMac #4490. This is an old school steel tooth file. I like it better than the modern diamond files for stainless frets. I bought this one about a year ago; my previous one was 35 years old and was starting to show some wear.

Crowning the frets, one at a time. about 15 minutes to do them all.

While doing the crowning, I'm watching those silver lines through the blue ink. On the frets that got filed down the most, like the 1st one on the left, the silver line is wide. Those frets need the most crowning. The frets where the silver line is skinny, like the 3rd one, only need a little bit of crowning.

The process is to file enough to make the wide lines equal in width to the skinny lines. But don't file so much that the skinny lines disappear, because that will ruin the leveling. The goal is to make all the silver lines skinny and equal in width. Equal in width on all the frets and all the way across each fret.

To finish up the crowning, I do a couple of quick swipes on each fret with an old worn-out StewMac diamond crowning file. This cleans off any little leftover tooth marks along the sides of the crown.

Polishing the frets: I use a variable speed Dremel, at fairly low speed, with a StewMac Green Polishing Wheel. I prefer the Green wheels only for stainless frets. The stainless shield is StewMac's narrow one, held down with two strips of black electrical tape. It takes about 5 seconds to polish each fret, then lift up the shield, move to the next fret, and stick it back down.

The polishing wheels need to be cleaned off every now and then by touching them lightly against the end of a round file.

After the main length of all the frets are polished, I go back down the neck, gently touching the ends of each fret, without the shield. This polishes the rounded end.

And that's it, the frets are done! I clean the silvery dust off with another wipe of StewMac Fingerboard Oil, and re-buff it.

This is what the ends of the frets look like, with the tangs trimmed back and the slots filled with black glue.

 

[Lo-E]

As usual, another clear, concise and informative description of a core lutherie skill from @Bruce Johnson. Your generosity with your knowledge and experience continues to amaze.

I was in Ventura County last week and I had hoped to borrow a car and drive out for another visit, Bruce, but family obligations got in the way. I really wanted to see the new shop layout. Oh well…. next time, I suppose.