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Repair

Article:    


The following article was generously provided by David Johnson of Scale Model Guitars located in Nashville, TN. David has worked on a few Travis Beans and was kind enough to provide some procedures for other luthiers out there that might not be familiar with Beans.

These articles are intended as informational resources to be used by professional guitar repair techs. The fact of the matter is that Travis Bean instruments have a very unique construction and therefore will require a different set of repair techniques. There is little to no technical repair information that exists online or in print because of the relative scarcity of these instruments.

A good repair tech is one who is experienced and informed. As I mentioned before, these articles are intended to provide information regarding repair techniques…more specifically, my repair techniques. They should not be taken as "the only way" to work on these instruments, I am simply sharing methods that have given me great results. My advice to any repair tech who gets one of these through their shop would be to read both articles through and use this information to proceed as you see fit, and with techniques that you are comfortable with. After reading, you will certainly have a greater knowledge of these very rare and remarkable guitars.

**Dave Johnson currently works as an in-house repair tech at Gruhn Guitars. He also operates Scale Model Guitars, a custom shop based in Nashville, TN. Dave can be reached by email at scalemodelguitars@sbcglobal.net.

Introduction.

In the following article, I will take you through the process of re-fretting a TB4000 that recently came through our shop. The purpose of this article is to provide insight as to exactly how Travis Bean necks will react during this process, and to document the techniques that I use to properly perform this task. Also, please keep in mind that Travis Bean guitars are in fact vintage instruments, and re-fretting a vintage guitar can in fact devalue it (certainly not as much as a refinish or changed hardware, but this is something to consider). In my opinion, there are only two instances in which a re-fret is appropriate on a Travis Bean guitar…when it is necessary to replace excessively low or worn frets, or when it is necessary to adjust neck relief in order to maintain playability. If the instrument has original frets that are in good shape and adjusted correctly, they deserve to remain on the guitar. These are factory-installed parts, and a part of that guitar's history. My advice to any of my customers would be to only re-fret when it is absolutely necessary.

Getting Started.

Here we have a Travis Bean 4000 Wedge bass that was brought to us for sale. Upon inspection, we discovered a substantial back-bow in the neck, even when under full string tension.

The first step is to measure the amount of neck relief with the strings both up to pitch (deflecting the neck) and then off of the guitar. Measuring with a 36" straight edge, I noticed 1/16" of back-bow on both ends of the neck when up to pitch, and 1/8" of back-bow on both ends with the strings removed. This particular bass also has a relatively thick neck, and is one of the models that incorporate a thick aluminum shim underneath the fingerboard. I need to make up about 1/16" of relief on both ends, in other words adding at least 1/8" of total neck deflection when under full string tension. The fingerboard is just 1/32" thicker than the depth of the fret tang, so a fingerboard level is out of the question, and at no point in the repair will I have the benefit of an adjustable truss rod. The TB neck itself is acting as its own non-adjustable neck reinforcement. Sometimes when a TB neck exhibits a minor amount of back-bow, you can "cheat" your way out of it with a light fret level focused on the center frets and/or increase string gauges. In this case, that is not going to happen. There is simply too much back-bow.

"So, why did this happen and what is the fix?" This particular TB neck is comprised of three parts: the fingerboard, the aluminum neck, and the shim sandwiched in between these components. I have had to remove and re-glue fingerboards on a number of these instruments, and have noticed on every singe one that once the fingerboard was removed, the neck itself was always perfectly level and true from end-to-end. Trust me, when it came to machining a perfectly true piece of aluminum, these guys definitely knew what they were doing. Where the design exhibits issues is with the use of a wooden fingerboard. Hardwood and metal have different expansion/contraction rates and will be affected by humidity changes differently. If you adhere a thin wooden fingerboard to an aluminum neck, the wood will expand and contract with the changing seasons, while the neck remains unaffected. Also, it is entirely possible that when these instruments were manufactured, they received their fingerboards kiln-dried and then manufactured them without any additional treatment. Over time, a kiln-dried piece of hardwood can take in moisture (humidity) and keep it. I would assume that when this bass was originally manufactured, it was setup with the correct amount of neck relief and then slowly over time developed a back bow. "So are you telling me that a thin piece of rosewood can cause such a dramatic amount of back bow on such a thick metal neck?" Absolutely…and the reason for this lies in the frets. As you know, a fret is attached to a fingerboard by its tang (the vertical part of the fret wire underneath the crown, the part that has "teeth"). When rosewood expands, it will wedge itself against each individual fret tang and therefore create a greater amount of back-bow. The way that you add relief to a neck with a non-adjustable truss rod is to remove material from the sides of the fret tang, you create narrower "teeth." Applied to just a few frets you might not notice any difference, but across an entire set of frets, you can make dramatic adjustments to control the exact amount of neck relief. Adversely, you can also move a neck in the other direction by "crimping" or expanding the fret tang. This technique has been around for quite some time, and it is the preferred method of repair when you are dealing with vintage instruments without an adjustable neck (for example, Martin guitars manufactured before 1985 all used a non-adjustable neck design). Also on this particular guitar, a fingerboard level would be that last thing that you would want to do. As I mentioned before, the fingerboard is just slightly thicker than the depth of the fret tang.

Pulling the frets.

At this point, I tap out the nut and begin to pull the frets. I used to use a 40-watt "wand-style" soldering iron to heat my frets, until I discovered the "fret zapper." It is basically a Radio Shack 140 watt "pistol-style" soldering iron with the tips replaced with lengths of brass. The brass is an excellent conductor, and can be easily bent to make contact with the fret about 1/4" inside the ends. You simply hit the fret for about a half-second before the glue is relaxed enough to pull. Way faster than the wand!

Immediately after "zapping" the fret, I use a diagonal cutter (sanded flush on the bottom side) to walk the fret out. I have used an end nipper style cutter as a fret puller before, but find the diagonal style to be way faster and cleaner. I can cleanly de-fret an entire fingerboard in less than three minutes using these tools. However, keeping in mind what I am working on, I think that I will take my time. It is also not a bad idea to save the original frets to be kept with the guitar.

Reading the fingerboard.

After pulling the frets, I then use a sanding block loaded with 220 grit sandpaper to lightly sand off any chatter surrounding the fret slots, this is a by-product of pulling the frets consisting of glue residue and wood particles and it is completely normal to see after removal. I then get another reading with the straight edge, this time with the fingerboard de-fretted. This time, I am noticing that the neck is still back-bowed but is way closer to true with the frets removed. The space that I gained was a direct result of pulling the frets, and gives me a very good idea of how to adjust the fret tang as I proceed. Preparing the fretwire.

At this point I have decided to "relax" the neck by removing material off of the sides of the fret tang. For this, I use a tool made by Stew Mac called the "fret barber." I start out by selecting a gauge of fret wire that has the same size crown and tang depth as the original frets and then pull it through this device. This is done before I bend or cut the wire (which comes to us in 2 foot lengths). I am only removing material from the sides of the teeth on the fret tang, stopping just short of removing all of this material. I need to preserve some of this rough surface on the tang in order to maintain rigidity of the neck and also to give the glue something to grab onto after the frets are installed and dialed-in.

Re-slotting and fretting.

The next step is to re-slot the fingerboard using a fret slotting saw with a depth gauge. I simply adjust the gauge to the exact depth of the fret tang and re-cut the slots. This cleans out any remaining glue residue from inside the slots and ensures that the frets go in clean. It is extremely important not to cut the fret slots too low. Nothing looks worse than a re-fretted guitar that has small spaces underneath the fret tang on the sides. I decided to go with Stew Mac wire #149 because it is very similar in crown size and tang depth to the original wire. This fingerboard is very thin, so it is important to select a fret tang that won't overshoot the wood line. Also, the thickness of the inner fret tang (in between the teeth) is identical to the original fret slot widths so I know that I will maintain rigidity in the neck. Next, I bend the fret wire. Travis Bean guitars all have a zero degree fingerboard radius, so I don't need to bend the wire excessively. Just enough to ensure that the fret ends sit down and seat properly. I would recommend applying a 16-degree bend. I then support the neck with a bag of shot wrapped in leather. This is the best re-fretting neck support that I have ever used, as there is absolutely zero kickback when hammering frets in. You can pick up a 25-pound bag at about any sporting goods or gun store that carries re-loading supplies; I would recommend the magnum shot, number 7 1/2. Next, I cut the bent wire to fit (extending about 1/4 inch over the sides of the board) and save them in a numbered block. There have actually been books written about proper fretting techniques, and entire chapters dedicated to the technique of hammering-in frets. The best advice that I can give is that the name "hammering" is deceptive…they should call it fret "tapping." Each light blow of the hammer should contact the top of the crown one single time with absolutely no "kick-back" or secondary-hit of the hammer. First, tap-in the fret ends, and then lightly work your way from the middle of the fret out to the end on either side. If you have ever experienced frets that kick-up when you are hammering them in, it is either because you are hitting too hard, your neck is not properly supported, or you did not properly over-bend your fret wire. The underside of the crown should "sit down" evenly and flush to the fingerboard, with absolutely no gaps whatsoever.

Testing neck relief.

After the frets are in, my next step is to re-string the bass and see how much the neck is deflecting under full string tension. Notice that I have not cut the fret ends yet, I have also not glued them in. I want to see exactly how much relief (if any) I now have after removing most all of the material off of the sides of the fret tang. I will admit that I did in fact get lucky the first time on this one…with the strings up to pitch, I now have about 1/64" of relief in the neck. This is just enough to work with, and is way better than the negative 1/8" that I started with! Hypothetically, in the event that I end up with too much relief, I would have pulled every other fret (remember, I didn't glue them in yet) and lightly crimped each one until I end up in the ballpark.

Gluing in the frets.

Now that I have the frets adjusted correctly I can begin to glue them in. I first apply paste wax to the fingerboard and fret edges making sure to leave a small space for the glue to work its way down into the slot. I just apply enough so that the glue will not stick to the top of the board.

Next, I use a super glue with a high viscosity to "wick" the fret in place (Stew Mac #10 thin super glue would be an example). After the glue is cured, I flush-cut the fret ends and begin the fret level.

Leveling the frets.

First, I use a sharpie to mark the tops of the fret crown.

Then I start my level with a short level sanding stick loaded with 220 grit sandpaper. I will begin by focusing my level in the middle of the neck with this short stick until I see that the sharpie marks are sanded away on each fret.

Then, I re-mark these frets and start over with a long stick that covers the entire fret span. It is extremely important for me to keep in mind that I am not shooting for a true fret level right now. The strings are off of the instrument at this point and the neck is back-bowed (since the strings aren't deflecting it). I have to compensate for this in my leveling technique, re-marking my fret crowns and focusing my sanding first in the middle, then toward the nut, then toward the end. I am essentially following the back-bow. Once I am able to remove all of the sharpie marks, then I know that I am finished and level. It is not a bad idea at this point to string it up again and play each note to see if I am getting any fret noise.

Dressing the fingerboard and fret ends.

Next, I use a 4mm bevel-edge chisel to remove any glue residue stuck beside the fret crowns. It is extremely important that you keep your chisels literally razor-sharp if you find yourself doing a good amount of detailed woodwork like this. A dull chisel can ruin your work in a second! Since I prepped the fingerboard with paste wax, the excess glue can be cut right off the top of the board with ease. On this step, I am following the edge of the fret crown and letting the tool do the work. You will clean up the rest of the area in between the frets on the next step.

I then take a razor blade and scrape the area in between the frets. This removes any remaining glue residue and leaves the fingerboard looking very clean. If I properly seated my frets, then I should be left with a fret job that looks as good or better than factory.

Next, I use a bevel-edge file to shape the fret crown ends. I am very careful not to overshoot the point where the edge of the fret crown makes contact with the edge of the fingerboard. This file will tear through wood in addition to metal, so I keep my eyes on my work.

The last step in dressing the fret ends is to flush up the ends of the fret tang protruding out of the fingerboard on the sides. The best method to clean this up is to take a fret end dressing file and work sideways, parallel to the fingerboard focused on one fret at a time. You want to be very, very careful not to accidentally hit any part of the aluminum with the file. Masking-off the sides of the aluminum neck would not be a bad idea here.

Finishing up.

Now we are at the finish line. The next step is to crown the frets. Since we are dealing with a zero radius board, it is important to keep the crowning file as flat as possible. I don't want to create a low fret by accident. The best way to avoid this is to re-crown the fret up to the point where you can still see a thin sanding line all the way across the top of the crown (the sanding mark left by the leveling stick).

Next, I use a fret guard and remove the sanding mark left by the fret level. I start with 320 grit paper.

Then, I wrap 400 grit paper around my index finger and sand the length of the fingerboard end-to-end hitting all of the frets along the way until the marks from the 320 grit paper are gone. Then repeat process with 600, then 800, then 1000, then 0000 grade steel wood. Notice that I do not mask off the fingerboard on this particular instrument. This is only because it is a rosewood board with small dot markers. If this were an "artist" model with pearl blocks, I would most certainly mask off the inlays before starting the final sanding steps.

The last step is to remove old glue residue from the nut slot before re-gluing the nut back in place. For this, I again turn to my 4mm chisel being very careful not to accidentally scratch the aluminum pegface surface. Before gluing the nut back into place, it is a good idea to check nut slot heights to see if they are tall enough. Since I re-fretted this bass with identical size fret wire, I did not have to adjust the nut. If you do in fact have to raise the nut height, I would recommend shimming it up with thin brass material (if your TB has a brass nut, most of them do) and then cutting the proper nut depths from the top. You can find this material at almost any hardware or art supply store. The last step is to re-glue the nut back in place using a five-minute epoxy, restring, and then adjust the bridge height and intonate.

A few final thoughts...

In this case, I was able to relieve a back-bow by manipulating the fret tang alone and without performing a fingerboard level. It is entirely possible that you may encounter a TB that has a dramatic back-bow…one where it is clear that manipulating the frets alone will not be enough. If you think that this is the case, then you might want to consider re-fretting with a tall fret wire and attempting a focused-level sand in the middle. Also, a light level sanding of the fingerboard is not entirely out of the question if it is one of the models that has a thicker board. Just be careful not to over-do it if you decide to go this route. You don't want to end up with a board that is noticeably thinner in the middle than at the ends, or even worse, one that "dips" in the middle when under string tension.

If all else fails, your final option would be to perform a fingerboard reset. By removing and then re-gluing the fingerboard you will essentially "reset" it back to level. Just remember to pull your frets before you re-glue the board back to the neck so it will conform to the aluminum, which should be level and true with the board removed. Then proceed to re-fret the guitar using the above instructions as reference.