Fretboard hump above fret #12

[Howie Dewin]

Reply from Dave Staudte (rhymms with “Howdy”) NB Guitar Repair (New Braunfels, TX):

It happens in almost every acoustic guitar. We have a thin flexible neck running into a very strong mass with the heel, heel block and entire body assembly. The back of the neck stretches and the top of the neck (fretboard with frets) compresses and bulges up. The best way to get rid of it is to pull the frets and plane the fingerboard. Sometimes you have enough fret height to grind it out of the frets as well. I don’t think it could be preemptively avoided in a build, other than putting carbon fiber or suitable stiffeners inside the neck. That has been done at Taylor with steel, and it works, adds weight though…they abandoned it for many years, it’s back now.

[Howie Dewin]

Thanks for a great answer. I am a retired sonar engineer, so your explanation makes perfect sense to me. I figured it had to be almost an endemic problem with acoustic guitars.

Next question: Can you recommend a ‘how to’ video with the best procedure for pulling frets to minimize damage to the fret slots?

Also, are there any rules of thumb regarding when to pull frets vs. file some down?

For example, my oldest acoustic is a Tama dreadnought that I have owned since the 1980s. The lowest 5-6 frets have deep scalloping under the two unwound strings. Another professional luthier recommended filing all the other frets down to the lowest scallop. Do you concur?

[Bryan Hutchinson – Hobbiest guitar tech]

Hi Howie @patreon_180038859,

Just saw some of your questions in your last post were not answered yet. Like you, I’ve been on a very steep learning curve since I started with guitar tech work on a hobbiest-level 5 years ago and I’ve learned everything from countless hours of watching YouTube videos and internet research (which often involves wading through reams of utter garbage, but as an engineer you should be able to see through that).

Regarding minimum fret height (i.e. new fret or file existing fret), this blog article by Gerry Hayes gives a great explanation and suggests minimum fret height measurements (you can sign up to his newsletters and follow him here on Looth Group if you like): https://hazeguitars.com/blog/fret-levels-and-refrets-redux

Regarding best procedure for pulling frets to minimize damage to the fret slots, just Google it and wade through videos.

At the risk of imparting unwanted advice, here are the some key considerations that were important for me when I started refretting guitars, maybe one or two points may be useful for you:

– Do you have a notched straight edge or similar tool to ensure the neck is truly straight before filing or levelling frets?

– Will something like the Stewmac “Fret Kisser” be suitable to achieve the remedy, or is more required?

– Does the issue warrant “compression” fretting to help remedy it? If so, do you have a suitable tool (e.g. fret crimper) to achieve this?

– Will it be necessary to plane and/or sand the fretboard to best remedy the issue? If so, do you have suitable tools and supplies? Additionally, if you do this you will probably need to deepen the fret slots, do you have a saw with the correct kerf width for the fret tang (e.g. refret saw or fret saw)?

– Will you use “chip stoppers” to help prevent chip out, or not (you’ll find them listed on Stewmac’s website which includes videos)

– Will you heat each fret with a solder iron immediately before pulling, or is there a possible risk to the finish on the fretboard? Do you know why heating the fret is a common practice?

– What quality of fret pulling tool will you be comfortable using if it’s a small job and you don’t plan on doing more guitar work (i.e. will lower quality tool result in damage?). Or can you borrow the correct tool (you can see different versions of fret pulling tools on Stewmac’s website)

– Make sure you have the correct sized fret wire to replace the existing frets (measure width, height and tang dimensions). Do you have suitable callipers to make the measurements and will you have to pull one fret first to check the tang dimensions?

– Do you have the correct tool(s) to radius the fret wire or can you buy the correct sized fret wire pre-radiused (to correct radius)?

– Do you have a suitable tool for cutting/nipping the fret wire without damaging it?

– Make sure your replacement fret wire is over-radiused correctly for the radius of your fretboard and the type of wire, and cleaned with naptha before installing. Do you have access to suitable radius gauges (Gerry Hayes had some free pdf’s on his website so you can print them on paper and then attach them to carboard and cut them out – that’s how I found his website 5 years ago)?

– Will you be gluing the replacement frets, or not (and why)? What type of glue will you use and will the frets need to be clamped or not once glued?

– Is you fingerboard bound or unbound? If bound, do you have suitable tools for undercutting the fret tang ends? Here’s a link to a great Stewmac video covering that process as well as the entire refret procedure: https://www.youtube.com/watch?v=BYTVAYgN1RE (worth watching regardless of whether you fingerboard is bound or not, it covers many aspects of refretting, and Erick Coleman is always a joy to watch!)

– Here’ another Stewmac video that has many nuggets of good info related to fret levelling that might answer some questions you may have in your mind. You can follow Gene Imbody here on Looth Group: https://www.youtube.com/watch?v=pN8leRZgnxM&list=PLtfY51hxxbEfBSJlOyqUibnWBEAgsawUG&index=4

-Do you have access to suitable tools for all aspects of the task? For example, is the beam you will use to level the frets truly dead-flat or would you be better off with a purpose built fret level beam (e.g. Stewmac has the cheaper “understring fret level beam” that I can recommend). Do you have a suitable tool and method for cleaning the fret slots before installing the new frets? Will you need a fret slot depth gauge, or not? Will you use a triangular file to gently chamfer the fret slots before installing the new frets?

– Do you have access to suitable tools for filing down the ends of the replacement frets (without damaging the sides of the fretboard) and do you have suitable materials to refinish any lacquer on the sides of the fretboard if it is damaged in the process?

– Is the fretboard suitable for filling with a wood dust and glue mixture to remedy any chip out? If so, do you have suitable wood to generate the required dust if you will not be sanding the fret board?

– Most importantly, do you have suitable tools to recrown the frets after filing/levelling them? If you don’t have a purpose built tool, will you grind of the edges of a suitable tri-corner file and be able to practice on a non-critical guitar first (it took me some time to master)?

– Do you have suitable abrasives in suitable grits for polishing out all tool and scratch marks after fret levelling, recrowning etc? Do you have suitable tape to protect the fretboard during the refret process?

In addition to the considerations above, let me leave you with links to some YouTube Channels that were real lifesavers for me when I first started learning guitar tech work (as your request for video links suggests you might not have already started the long process of sorting garbage from gold on the internet):

– https://www.youtube.com/@stewmac

– https://www.youtube.com/@OBrienGuitars

– https://www.youtube.com/@BeauHannamGuitars (you could also follow him here on Looth Group)

– https://www.youtube.com/@flameguitars5770

– https://www.youtube.com/@HighlineGuitars

– https://www.youtube.com/@harpethguitar (you could also follow Scott here on Looth Group)

– https://www.youtube.com/@twoodfrd (you could also follow Ted here on Looth Group)

– Any video on YouTube that has Dan Erlewine in it! (you could also follow him here on Looth Group)

I hope at least some of this is useful to you! It might give you a couple of things to consider and research before you finalise a plan.

Cheers, Bryan

hazeguitars.com

Fret levels and refrets: Redux — Haze Guitars

When can you get away with a fret level and when do you need to go all out and refret an instrument? There's a time and a place for both jobs. Read on to get a feeling for when you … Continue reading

[Ian Davlin The Looth Group]

Perfect!

[Ian Davlin The Looth Group]

You can definitely do that. One thing I might add is that you can measure first to make sure the frets have enough meat to effect positive change. Adjust the neck straight, put a straight edge on the board that covers at least back the the 7th fret and then forward over the hump. There should be a gap forming between the straight edge and the frets, before the hump. Measure the gap with feeler gauges. This will give you an indication of how much you will need to remove from the hump.

Below is my fret leveling rig. Home Depot sells a construction level with machined aluminum surface which is actually quite reasonable.

I like to only put abrasives on the area of the beam making contact with the hump. Then I add tape to make sure the rest of the beam is coplanar with the abrasive. This prevents me from sanding a dip into the start of the hump.