Why should fret crowning feel like punishment?

All other fret crowning files force you to death-grip. SharkFin changes that.

You can literally un-grip during the cutting stroke – and be relaxed on the back stroke – because the SharkFin handle conforms to and grips your hand, which is directly on top of the action, so you’re not gripping and steering from behind a long handle.

If you’ve done enough fretwork, you already know the moment – forearm tight, wrist getting cranky, dented fingertips, grip turning into a death-claw… and you’re only halfway through the fret job.

I know it because I’ve lived it.

Repetitive stress took my fret crowning hand out of the game for quite a while. I was able to avoid surgery, but it took rehab, cortisone shots, and a whole lot of patience to earn the use of my hand back. I promised myself two things: Never again for me – and if I could help it, never – at all – for you.

That’s why SharkFin exists.

Here’s the counterintuitive truth: a typical file handle doesn’t give you leverage over the work – it gives the file leverage over your hand. The longer the handle, the less direct downforce and control you actually get at the teeth.

Here’s a thought experiment: If you were to double the file’s handle length, you’d also cut your effective downforce (and control) by 1/2. That’s why crowning often feels like you’re fighting the tool, not shaping the fret.

So we flipped the whole pre-conceived notion of what a fret crowning file is, on its head. And then set out to create what a fret crowning file can – and should be.

The new SharkFin file is the most advanced and accurate guitar fret file ever created, and the first crowning file worthy of being a FretGuru.

Avoid deep scratches in your frets and fingerboard with the FretGuru SharkFin's precisely shaped, sharp cutting teeth and smooth file edges, that give you total control, cutting accuracy and safety.

A precision tool designed to deliver exceptional fretwork results. Crafted with from high carbon European steel, which is heat treated and hardened to extreme levels, this file ensures smooth, clean, and accurate fret crowning, with superb control of your fret centerlines.

The Diamond SharkFin version features a high quality steel body with finely graded 300 grit industrial diamond – which we've found is the sweet spot for controlled yet effortless cutting, without creating deep scratches that are difficult to sand and polish out.

The diamond version also has the benefit of cutting in both directions, and is less prone to filling with gummy nickel silver fret debris than steel teeth files.

With the top-secret and proprietary D.I.A. (Dual Integrated Arc) cutting geometry, and the unique, soft, molded handle, this allows for precise shaping and crowning of frets, enabling luthiers and guitar technicians to achieve impeccable fretwork with ease.

Available in 2 sizes (identical sizing to the Dagger 2.0):

• MD/LG/XL covers fret widths in the range of ~0.085” to (barely) ~0.110”. If you’re doing vintage or 6105 frets, this is the file to get.

• LG/XL/XXL covers fret widths in the range of ~0.095” to ~0.118”+.

  • This is the file to get if you’re doing “modern” electric guitars, with typical jumbo frets, all the way up to Super Jumbo and huge frets.
    
    This size is also ideal if you have ~0.104” to 0.110” frets that have been significantly worn or leveled, where it can be helpful to start with the XXL side, which is able to take a wide enough “bite” of the fret, in order to bring the sides in. From there you can switch back to the LG/XL side to create a more clearly defined fret centerline.

**Both file file sizes share the same LG/XL/6100 side**

Whether you're leveling, crowning, or shaping frets, the revolutionary FretGuru SharkFin file is an indispensable tool for creating the tightest possible fret crowns, while achieving professional-grade fretwork and maintaining optimal playability.

MAXIMUM TONE & PLAYABILITY STARTS HERE:

FretGuru XT is the Mother of All Guitar Gauges*.

The most advanced, accurate, precise - and capable - guitar measurement tool ever created. 

After many years of development, testing, and perfecting, the new FretGuru XT (10-in-1 Advanced Ultra-Precision Guitar String Action Gauge with *MOAGG Technology) is ready for action on your workbench (and way more than just “string action”).

Building on the foundation laid by the original, compact-yet-mighty FretGuru 2 (8-in-1 Guitar String Action Gauge) the expanded format of FretGuru XT (10-in-1 Advanced Ultra-Precision Guitar String Action Gauge with *MOAGG Technology) has allowed us to maximize the useful features of the original, while bringing new and exclusive, game-changing capabilities to your workbench. 

It's an ultra-precision, professional, heirloom grade tool worthy of any workshop or guitar factory - yet still pocket-sized.

Many of the world's busiest A-List guitar shops, leading techs, and brilliant luthiers have told us their most often reached for tool is the original FretGuru 2 gauge, as there's no quicker, easier way to evaluate a guitar when a new client walks in the door … The new FretGuru XT Gauge is about to change that.

While we didn't specifically design FretGuru XT to replace the original FretGuru 2 Gauge, FretGuru XT is a significant upgrade in function, features, readability and ease of use, making it the perfect choice for any demanding, precision-obsessed guitar tech or luthier.

FretGuru XT MOAGG Technology & Feature Exclusives:

• New Bridge and Pickup Spacing Ruler: This exclusive, first of its kind function eliminates the guesswork of knowing which bridge and pickup spacing you have, or need ( or want ;- )

  • No precision calipers? No problem!

  • SAE and Metric for F-Spacing, G-Spacing, acoustic and many more!

• New Nut Width and String Spacing Ruler - Gives you a quick and handy evaluation and reference for measuring existing nut or neck widths, or setting up a new nut.

• Expanded, 4-sided Fret Rocker Functionality, with Extra Thickness: Moving beyond FretGuru 2’s 3-sided Fret Rocker functionality, FretGuru XT expands the capability with a 4-sided Rocker to help you accurately and seamlessly find any high frets up to 24th fret and beyond on many guitars and smaller stringed instruments!

  • FretGuru XT is over 40% larger in surface area and nearly 40% thicker than the already incredible, previous iteration FretGuru 2, meaning you’ll feel less need for a separate, dedicated fret rocker.

    • It’s your ideal guitar measuring tool, without constraint / size limitations, and, mind-blowingly, as much as 70.6% thicker than competitors.
      

• New, Angled-Depth Gauge / Rule Placement: Allows for easier maneuverability when measuring pickup height, with improved clearance of the neck and bridge.
  

• Redesigned Fret Height / Fret Wear Notches: Provides a positive tactile feel during use, with effortless and accurate fret measurement.

  • You can now feel it working.
    

• New Hang Hole: Smooth, elegantly chamfered hang hole means your FretGuru XT gauge will always be within easy reach on your pegboard or tool wall with your other tools for quick-draw measurements.
  

FretGuru XT / FretGuru 2 String Action Gauge Shared Features:

• Laser-Etched Markings & Anti–Glare-Coated Black Finish: Supreme readability with no printing to rub off.
  

• Microscopic Flatness On All Sides: Ensures precise measuring and fret rocking, thanks to every FretGuru Setup and Evaluation Gauge being individually laser cut/ultra-precision CNC machined, and then diamond honed and polished edges.

  • A joy to hold, with no scratched frets guaranteed!: You'll marvel at the silky smooth edges, and how much effort and obsessive attention has gone into them.  

    • There are 45+ steps and separate moves by CNC machine or by hand that go into the edges alone for FretGuru XT.

      • Competitor gauges are lucky to get a quick run on the belt sander (if anything at all).
        

• High-Quality, Precision Stainless Steel Construction: Engineered from the ground up as precision measuring and evaluation gauges (not just re-purposed, imprecise metal business cards like competitors).

  • (FretGuru is also proud to highlight that the latest batches of FretGuru 2 also feature the same, nearly 40% thicker construction! as FretGuru XT

    • *Compared to previous iteration FretGuru 2 batches.
      

• Exceptionally Comfortable: Holding it in hand feels great thanks to masterfully beveled edges and rounded corners.
  

• Dual Precision String Action Rulers: For 0.010” measurements (ten thousands of an inch up to 0.130”) or 64th” measurements (1/64ths of an inch up to 9/64” ) — including half increments in .005” and .5/64th (½ of a 64th) measurements!
  

• Shop Rule Function: For general precision measuring up to 2-1/4” in 1/32” increments.
  

• Depth Gauge / Rule Function: For measuring pickup heights, saddle height, acoustic saddle slot depth, and more.

  • FretGuru XT: Up to .750" in .025" increments / up to 19mm in 1mm increments with MOAGG Technology for better measuring clearance near other guitar parts.

  • FretGuru 2: Up to 1.00" in .025" increments / up to 16mm in 1mm increments

• Fret Height / Fret Wear Depth Notches:

  • Helps you quickly decide on just a setup or more advanced fret leveling without specialized calipers.

  • Instantly figure out fret size when guitar shopping.

  • Quickly evaluate your guitar and determine whether your frets can be leveled, or need replacement.

    • FretGuru XT: Notches from .025" to .055" for visual reference with MOAGG Technology for tactile feedback

    • FretGuru 2: Notches from .025" to .055" for visual reference
      

• Extra-Thin Nut Slot Height Measuring Corner: The thin corner is an engineering feat in itself, measuring just 0.0095” thick, which allows you to rest the gauge in any nut slot (as small as the high e-string, .010”) and then across to the second fret, so you can glide a feeler gauge between the gauge and 1st fret.

  • This helps you avoid tone-killing fret buzz and notes that pull sharp on the fret few frets.

  • FretGuru XT also includes a new on-gauge diagram and specs chart for easy referencing!
    

• Inch/Metric Conversion Chart: Etched on the back to save you time when working between SAE and metric parts. 

  • Larger type on FretGuru XT for easier readability, thanks in part to its over 40% larger surface area!
    

• Included Genuine Leather Protector Sleeve: Expertly crafted and heavy-duty stitched for long-term durability. 

  • A very premium addition, truly worthy of the heirloom-quality, precision tool it protects, which guarantees your investment lasts a lifetime. 

  • Also features a pegboard hang hole and a classy hot-branded FretGuru logo.

The latest Dagger 2.0 file is the most advanced and accurate guitar fret file ever created, and the first crowning file worthy of being a FretGuru.

Avoid deep scratches in your frets and fingerboard with the FretGuru Dagger 2.0's precisely shaped, sharp cutting teeth and smooth file edges, that give you total control, cutting accuracy and safety.

A precision tool designed to deliver exceptional fretwork results. Crafted with from high carbon European steel, which is heat treated and hardened to extreme levels, this file ensures smooth, clean, and accurate fret crowning, with superb control of your fret centerlines.

With the exclusive D.I.A. (Dual Integrated Arc) geometry, and the unique dagger-shaped profile, this allows for precise shaping and crowning of frets, enabling luthiers and guitar technicians to achieve impeccable fretwork with ease.

Now available in 2 sizes:

• The original Dagger 2.0 MD/LG/XL covers fret widths in the range of ~0.085” to (barely) ~0.110”. If you’re doing vintage or 6105 frets, this is the file to get.

• The new Dagger 2.0 LG/XL/XXL covers fret widths in the range of ~0.095” to ~0.118”+.

  • This is the file if you’re doing “modern” electric guitars. This size is also ideal if you have ~0.110” frets that have been significantly worn or leveled, in which case the XXL side is able to take a wide enough “bite” of the fret, in order to bring the sides in to a more clearly defined fret centerline.

**Both file sizes share the same LG/XL/6100 side**

Whether you're leveling, crowning, or shaping frets, the FretGuru Dagger 2.0 file is an indispensable tool for achieving professional-grade fretwork and maintaining optimal playability.

Looking for a FretGuru Dagger Crowning File with a Diamond cutting surface and an additional curved side that makes spot leveling and upper fret crowning even easier? Explore the new Diamond Dagger 2.0 Guitar Fret Crowning File, featuring the same advanced geometry as the original with a diamond cutting surface that many luthiers and guitar techs prefer.

*Box graphic is for illustrative purposes only.

The Diamond Dagger has evolved…
into the Diamond SharkFin

Diamond Dagger DNA. SharkFin control.

If you came here looking for the original Diamond Dagger, you’re not lost.

The Diamond Dagger earned a loyal following because it brought FretGuru’s D.I.A. crowning philosophy into a diamond format many luthiers prefer – smooth, controlled, accurate, fast-cutting, and built for tight fret crowns.

But rather than simply repeat the same design, we carried that diamond concept forward into our newest crowning platform.

Meet the FretGuru Diamond SharkFin

The Diamond SharkFin gives you the diamond crowning experience that demanding luthiers, repair techs, and passionate guitar geeks loved in the Diamond Dagger – now with the top-down control, relaxed grip, and natural hand position that make SharkFin feel so refreshingly different at the bench.

In head-to-head testing, the Diamond SharkFin delivered everything we loved about the Diamond Dagger – but with better comfort, control, speed, and cutting feel.

Same precision-first D.I.A. philosophy.

New SharkFin control.

And now with a durable, fast-cutting 300 grit industrial diamond surface that cuts smoothly in both directions.

The Diamond Dagger didn’t disappear.

It evolved.

Or, less formally:

It got swallowed by a Shark.

Diamond cutting feel. SharkFin control.

The SharkFin design puts your hand directly over the cutting action, giving you more direct control over the fret crown and centerline. Instead of death-gripping a long handle from behind the work, you can guide the file from above with a more relaxed, natural stroke.

With SharkFin, the shape of the handle plus the natural weight of your hand, combined with D.I.A. geometry and fast-cutting diamond grit, do most of the work for you.

Luthiers who’ve used the SharkFin have been thrilled with the fatigue-reducing benefits of the design. It’s counterintuitive just how little effort it takes compared to conventional crowning files:

—————————————————————————————————————————

Very Comfortable!
5 out of 5 stars

This thing is amazing. My hands get fatigued very quickly. I was actually able to crown the entire neck in one sitting.

SD – Amazon Verified Purchase

—————————————————————————————————————————

For those who’ve spent years, or even decades, crowning with traditional files, it can be helpful to do a quick mental reset when beginning to use SharkFin by asking:

How lightly can I grip?

How little pressure can I use?

The 300 grit industrial diamond surface cuts fast, clean, and smooth in both directions, making the Diamond SharkFin an excellent choice for stainless steel, nickel-silver, and precise high-control fretwork.

And with a diamond cutting surface, there’s no need for constant cleaning to stay ahead of fret debris getting stuck in the teeth.

Just durable and precise diamond cutting performance, with the most comfortable and controlled fret crowning format ever: SharkFin.

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Life changing for fretwork!
5 out of 5 stars

This thing is unbelievable, completely changed how I approach fretwork. Used to dread it, and felt like I was guessing – with this hand position I know where I am on the fret, and have way more control.

Also super easy to throw on various grits of sandpaper to get to a final polish. Game changer!

Chapman Swaine – Amazon Verified Purchase

—————————————————————————————————————————

First batch is limited

This first production run is very limited, and people on the waitlist are getting the first heads-up (and the waitlist is much larger that the amount of files on hand).

If you were waiting for the Diamond Dagger, this is the evolution of that design philosophy:

Diamond Dagger DNA.

SharkFin control.

300 grit industrial diamond cutting power.

Features the same exact MD/LG/XL size and D.I.A. cutting geometry as the Diamond Dagger, which covers fret widths in the range of approximately 0.085" to 0.110".

If you’re working on vintage-style wire, 6105, medium jumbo, or most common modern fret sizes, this is the Diamond SharkFin to get.

The Diamond Dagger set the direction.

The Diamond SharkFin moves it forward.

—————————————————————————————————————————

Excellent file - no pain and excellent results!
5 out of 5 stars

I’m part of the way through my first level and crown with the SharkFin file and I can already say this is a HUGE upgrade from the baroque file and the copy of the dagger file that I’ve been using.

It makes a much nicer crown with very little pressure, and the file shape makes it completely painless. I have psoriatic arthritis, so anytime I did a crown and level I was out for the count the rest of the day and often the next.

Pain from other files made my neck, shoulders, and hands feel like they were on fire, then locked up. This is going to make it so much easier and the result are going to be better.

I bought the diamond coated version, and I’m glad I did that, I’m sure that has a lot to do with the minimal pressure needed.

But the handle shape, putting your hands right over the file as you use it, is making a big difference too.

I could feel what I was doing much better, and I didn’t have to tilt the file as much at the edges, which will lower the chance of fretboard damage as well as being more consistent with the neck radius.

This is 100% recommended.

• The most advanced and precision fret end dressing file available - designed from the ground up specifically for fret ends - this is your most effective weapon in the battle against sharp fret ends, "fret sprout,” and a must-have for a smoother, faster playing guitar that inspires you to play more often.

• Precision flat ground, diamond honed and polished bottom - so the file glides across your fingerboard without scuffing the wood, finish or binding. We've teamed up with one of Europe's oldest and most respected file makers to help us create this finely crafted file, then we put the finishing touches and final diamond hone and polish here in our shop.

• Top of file has a smooth, safe ground edge, and the upper corners and tip are completely rounded and beveled to prevent damage to your fretboard and guitar. Also comes with a top quality, made in USA hardwood handle that feels comfortable in your hand, and takes the pain out of working on your frets.

• Innovative Double Ski-Tip design, to protect your guitar top from scratches and dings.

• Comes with a “hot-rod” orange TPU (thermoplastic polyurethane) sheath to protect the file and allow for hanging on a pegboard.

*Box graphic is for illustrative purposes only.

The hyper accuracy of the second edition FretGuru 8-in-1 Precision String Action Gauge will help you bring your guitar into another world of playability that’s measurably unmatched.

Here are the highlights:

• Precise String Action Rulers for 0.010” (ten thousands of an inch) or 64th” (1/64ths on an inch) measurements — including halved measurements!

• Laser-etched markings deep through the durable, anti-glare-coated black finish and metal mean supreme readability with no printing to rub off.

• Microscopic flatness on three sides ensures precise measuring — you can even use it as a fret rocker in a pinch — thanks to being individually laser cut, CNC machined and then diamond honed and polished.

  • Also ensures our gauge is less likely to scratch guitars thanks to a silky smooth finish (no belt sander marks here!).

• Made of high-quality stainless steel and engineered from the ground up as a precision measuring and evaluation gauge (not just an imprecise metal business card like many competitors).

• Shop Rule / Depth Gauge function for up to 2 1/4” / 16mm for everything from pickup height to string spread.

• Fret Wear Depth Notches help you quickly decide on just a setup or more advanced fret leveling without specialized calipers.

  • Also great as a Fret Height Checker!

• Extra-thin Nut Slot Height measuring edge lets you rest the gauge in any nut slot (as small as the high e-string, .010”) and on the second fret, so you can glide feeler gauges under the 1st fret.

  • This helps you avoid tone-killing fret buzz and notes that pull sharp on the fret few frets.

• Inch/Metric Conversions on back to save you time when working between SAE and metric parts.

• Exceptionally comfortable to hold thanks to front-to-back beveled edges and rounded corners.

• Includes durable, genuine leather protector sleeve.

• Also available in Metric+ version.

Level frets are part of the key foundation to making your guitar play like buttah. A fret leveling beam lets you establish level frets across your guitar's entire neck. Did you know that a fret only .001" (one thousand of an inch) higher than its neighbors can cause frustratingly noticeable playability issues? Things like fret buzz and decreased sustain that will negatively impact your playing experience.

Most other "precision" fret leveling beams out there only guarantee leveling accuracy to within .0015" across a 12-inch span. We believed we could do better and we did -- made right here in California:

FretGuru's leveling beam isn't just precise, it's ultra-precise. How? Made from 6061 T6 seamless aluminum, it's meticulously ground (not milled), and lapped to within an unmatched, seemingly impossible .00015" (fifteen hundred ten thousands of an inch) accuracy across the entire span of each beam. Yes, that's 10x more precise.

That means being able to achieve the lowest string action possible with ease come setup time after recrowning the frets with one of our Dagger Fret Crowning Files.

Not only that, it ships with a few complimentary strips of our most advanced Ceramic Sandpaper Strips for Fret Leveling Beams with Advanced Film-Backing (Peel and Stick).* These strips are specifically made to compliment this level of ultra-precision that only FretGuru offers.

Additionally, we added some bonus features that make FretGuru Leveling Beams a joy to use:

• Removable plastic end caps: Ensures you don't damage your guitar's pickups, nuts or tuners during a fret level.

• Durable, anodized finish: Easy grip, and finished in a hotrod-esque, candy blue with laser etched logo.

• Hang hole: When you’re done leveling, you can proudly hang it with your tools thanks to a strategically placed and beautifully countersunk “hang hole.”

Available Lengths:

• 8" – Great for spot leveling, ukulele / uke, mandolin (8” x 1" x 2")

• 10" – Ideal for ukulele / uke, mandolin, cigar box guitar (10” x 1" x 2")

• 16" – The ideal and go-to size for professional grade guitar fret leveling (16” x 1" x 2" )

• 21" – Ideal for bass guitars and can be used on guitars with great results (21” x 1" x 2")

*Ships with premium 240, 320, 400, & 600 grit peel and stick sandpaper included.

THE MOST ADVANCED SANDPAPER EVER CREATED FOR GUITAR FRET LEVELING:

(240, 320, 400, 600 grit is Advanced Film-Backed Ceramic. 100 grit is our red premium aluminum oxide).

Close collaboration with our state-of-the-art sandpaper factory has created a fast and smooth cutting, highly consistent and durable sandpaper of unrivaled performance.

Starting with polymer film backing of perfect thickness (instead of flimsy, lumpy paper), with a fine layer of precision graded industrial ceramic super-abrasive – the gold standard for metal working. Even so-called premium sandpaper can’t compare.

The benefits of this sandpaper are how precise and uniform thickness the poly film backing is compared to paper, as well as a proprietary gluing process that is also super uniform, along with precisely graded ceramic grains, makes for superb accuracy and durability.

It's also much easier to remove, comes off in one piece when it's time to replace it, as the film backing removes in one piece, rather than scraps of paper.

*Each 5-pack includes a storage case and naphtha-based adhesive removal wipes, which work great in removing sticker adhesive without damaging the finish. The single strip options do no include the case or adhesive removal wipes.