Welcome to the Workbench!

You have found your way into the Ithaca Guitar Works' repair department web page.  Located on the first floor of the Dewitt Building directly above the store's sales floor we perform repairs and modifications to stringed instruments of all types.   We do everything from major restorations to set ups.  Within this section of the store's web page you will find useful information regarding the care and maintenance of your stringed instrument, lectures on what not to do to your instrument and descriptions of some of the more common repairs we perform.  You can also find photos and text relating to some of the more interesting projects we've been working on.

above: bridge reglue/replace and finish under pickguard

Extreme Changes in Humidity and Your Fretted Stringed Instrument

1/17/06

As winter sets in here in the North East U.S. the air gets extremely dry.  Guitars, being constructed from wood, are often damaged by these extreme fluctuations in humidity.  Most professional fretted stringed instruments are constructed from solid woods, which are particularly vulnerable to changes in humidity.  We see a multitude of dried out instruments cross our workbench each winter. 

The symptoms of a dried out guitar are many.  Look for protruding fret ends (the nickel/silver frets don’t shrink as the wood does so the fret ends protrude from the side of the neck) and a concave or underbowed neck which will cause buzzing and high action.  

Flat top acoustic guitars are even more susceptible to changes in humidity since the wood that makes up the box are thin and typically unfinished inside the instrument.  Beyond the usual fair regarding the neck as described above, an acoustic guitar will suffer cracks in the body.  Also, the top of the guitar will sink as its moisture content is diminished causing low action and buzzing.  Since an acoustic guitar has so many glue joints (the bracing, side/back, side/top, bridge, etc…) when the instrument expands and contracts with extreme fluctuations in humidity these glue joints will fail causing loose braces, lifting bridges and, well you get the idea…

The solution is simpler than most folks anticipate.  Keeping your instrument in its case when not being played and utilizing a soundhole humidifier will keep most instruments (even electric guitars, remember, necks are made from wood too!) from getting extremely dried out.  The type that I recommend is the “damp-it” brand.  Damp-its are essentially a cylindrical sponge encased within a rubber hose sporting multiple holes.  The damp-it must be re wetted and monitored on a regular basis.  They are made in a multitude of sizes for instruments ranging from dreadnaught guitars to violins.  I use two of these devices in my guitar each winter and one in my mandolin.  If you’re not sure which damp-it is right for you or have any questions about how to use it feel free to contact us.

Happy playing!

Interesting Projects

Adjustable Dreadnaught Form

Well I finally did it.  I bit the bullet and made an adjustable form to allow for the faster regluing of plates with greater accuracy.  Every now and again we have to take apart a guitar to get at its insides to perform some pretty serious repairs.  Whenever possible I like to reuse the guitar's original binding and keep the factory finish as intact as possible.  In order to better achieve this I began using an adjustable form  to allow for more accurate alignment of sides and plates (tops or backs) during a "buttoning up" (putting a guitar back together).

Onto the pictures...

Although I didn't have the foresight to document the first stage of the project, suffice it to say that I painstakingly handmade a half cutout of a martin dreadnaught guitar to use as a template out of a piece of 3/4" plywood. 

After I rough cut all the pieces I would need for the form with a band saw  I stacked them and drilled holes through them all to allow for a means to accurately align the rough cut wood with my template via 1/2" dowels.  I then cut the individual pieces to size with my homemade router table and a flush cutting bit.  The idea is that the ball bearing on the shaft of the bit runs along my template and the flutes (cutting surfaces of the bit) trim the rough cut piece to size.

Then I glued and clamped all of my pieces of plywood.

Here you see the glued form laid out on a work board I've cut out of yet another  piece of plywood.

Once again I forgot about the camera but the last two steps were to cut my form up into 14 small pieces (with material removed from in between) and bolt those pieces to the work board.  The work board has slots I cut with the router that allow me to move the blocks that make up the form fore and aft.  Obviously, the bolts, when loosened, allow the blocks to turn from side to side.  Here's the completed form holding the D-35 it was modeled after.  This guitar got a new top, but we'll save those photos for another time...

Pragmatic vs. Antique Restoration

Here at the Ithaca Guitar Works repair department we practice two basic "philosophies" of repair.  This depends upon the value/historical significance of the instrument in question, the client's budget and goals regarding playability and future maintenance. 

Instrument repair (which is, of course, a means to an end) often takes two different forms, depending upon the desired outcome of repair.  It is important to give your full consideration to the differing repair “philosophies”.  These two methods can be defined as a practical player’s (or Pragmatic) approach and collector’s (or antique restoration) approach. 

The Pragmatic approach emphasizes an amalgamation of structural integrity, a more reasonable budget and potentially less future maintenance. Conversely, antique restoration keeps the instrument’s value as a collectable antique as the main priority.  In this approach keeping an instrument “original” is the main goal: whenever possible old parts are repaired and reused and all modifications are avoided. 

Resources for Luthier’s and Repair Persons

A high degree of patience is a must in this field.  The luthier/repair person must possess a love of the process if they are to produce acceptable work. 

There are many ways to approach most problems that occur with fretted stringed instruments.  The more tools you have (not available for sale in catalogs, knowledge and experience are the two most important tools you can possess) the better your work will be.  Repairing and building guitars requires many skills borrowed from a multitude of trades.  If you are working with electric guitars it is essential that you understand and can construct/repair electrical circuits.  Almost all guitars are constructed from wood so basic woodworking skills are a must.  As to wood working it is important to draw from the various woodworking traditions, be they Western or Japanese, violin construction or cabinet making.  All of these traditions have tools, concepts and hundreds, if not thousands of years of refinement to offer to the guitar builder/repair person.  In short, absorb all that you can and keep an open mind.

We here at the Ithaca Guitar Works repair department love helping out customers beyond actually repairing instruments by answering general maintenance questions and explaining the repairs we propose for our client’s instruments.  Unfortunately we don’t have the time to answer in depth questions for you weekend warriors out there.  There’s just not enough time in the day (everyday I’m amazed at just how many instruments are out there and all of them require periodic maintenance!).  So following is a list of some of the many resources out there for aspiring luthiers and repair technicians. 

There are a number of good resources available to the general public that are very detailed and could probably articulate the various repair and building processes I use better and more in depth than I could.  It is important to remember that there are many “valid” and effective methods for repair, restoration and building.  The end result: a good sounding, easy to play and aesthetically pleasing instrument is the most important goal in instrument repair.  Repair and building methods are, therefore, only a means to an end.  With that in mind, following are a number of resources I found helpful in my development as a stringed instrument repair person.  Most of these texts listed are available for sale at the Ithaca Guitar Works.  Need help locating guitar repair related books?  Just contact Charles on the retail floor at the Guitar Works.  He’s the resident librarian.

A book that I've learned a lot from is "Guitarmaking: Tradition and Technology" by Cumpiano and Natelson.  In this book the authors document with great detail the process of building a classical and a steel string “folk” guitar side by side from rough wood stock to finished product. 

Another great resource is the Martin repair manual.  This short, but informative book was initially published, I believe, to familiarize the factory employees and service center technicians with the Martin factory’s repair techniques.  This manual only provides basic repair concepts without too much detail.  Therefore it should be used in conjunction with other resources that can help build a more complete picture of the methods described within this particular text.

"Complete Guitar Repair" by Hideo Kamimoto is another very valuable resource for the aspiring or practicing repair technician.  This book covers a lot of ground and has a fair amount of detail. 

Don Teeter's book titled "The Acoustic Guitar" is another informative repair resource.  This was the first repair text I ever encountered and I still use many of the techniques and jigs described within this book’s pages. 

Other valuable luthier/repair tech media: The Guild of American Luthiers and the Association of Stringed Instrument Artisans (A.S.I.A.) have both published a lot of information.  “Guitarmaker” magazine is ASIA's quarterly publication that has tips, stories and pictures regarding both stringed instrument repair and construction. 

An online resource held in high regard by professionals in the repair field is Frank Ford's informative website www.frets.com. 

There are a host of other magazines, videos and books, not to mention hands on workshops and luthier schools that are used regularly by professionals for the consumption and dissemination of information.  Stewart Macdonald and Luthier's Mercentile are two mail order supply houses that help spread techniques, technology and other information related to the field.

Repair Descriptions

A Quick Explanation of the Term "Set Up"

The term set up means something different from repair bench to repair bench, but our definition of a set up includes the following: dressing the frets (filing away string wear, recrowning and polishing the frets), cleaning and sealing the fingerboard (with oil or wax), oiling the tuners, restringing, and adjusting the truss rod, nut slots and saddle for intonation and playability.  Prior to the set up it is important to have us restring the instrument with the specific gauge and tension of strings you will be using in the future (such as light, medium etc…).   This way all of the adjustments we make correspond to the way your instrument reacts to the tension of your gauge of strings.

Why Get A Set Up?

The main reason to get your instrument set up is to make it play and sound as good as possible.  As a fretted instrument is played the frets ware substantially over time.  This leads to problems with buzzing, unbalanced action, improper string height at the nut,  “snagging” when the string is bent and a general degradation in the “feel” of the instrument. 

Similar to tuning up a car, setting up an instrument requires many interrelated adjustments.  Frequently a customer will bring in an instrument requesting that we only adjust one aspect such as the intonation, truss rod, nut or saddle.  Unfortunately this is not always possible because these various aspects of playability and tuning are inter related.  For example, properly adjusting the truss rod may create fret buzz.  This may be caused by multiple factors such as the instrument is too dry (as often happens in the dead of winter in the North East) causing the top and, consequently the saddle, to sink too low.  Or perhaps at some point the saddle was adjusted without properly adjusting the truss rod first.  Sometimes a warped fingerboard with “high” and “low” frets will not prove problematic until the truss rod or saddle is adjusted.  In the same regard, proper intonation is dependent upon a correctly adjusted truss rod and properly crowned, unworn frets.  At this point you can see how simply adjusting the truss rod or intonating an instrument, or even adjusting the saddle can set off a chain of related adjustments. Therefore, when we make all adjustments for playability or proper intonation we call this a set up. 

Bone Saddles and Nuts

I only use bone for nuts and saddles with the following exceptions: situations where a customer specifically

 requests another material for cost or aesthetic reasons, some student instruments that will accept a properly 

fitting plastic replacement part with little or no alteration and Taylor guitars which are designed to accept a 

prefabricated factory nut and saddle made of a synthetic material.  

Although I will not weigh in on the debate currently taking place amongst guitarists regarding which materials 

for nuts and saddles have the best sonic advantages I can say from experience that bone  holds up better to 

wear than any material I’ve used (the jury is still out on corian, though my initial observations show promise 

for the material’s durability).

Bowed Neck/Fretboard Tongue Lift

Throughout the course of a stringed instrument’s life it is under constant string tension (150 plus pounds on a steel string guitar!).  The steady load of pressure slowly collapses the instrument in on itself.  Though a good guitar will last a life time if properly cared for, it is likely that at some point the neck of the instrument will need to be straightened.  Many stringed instruments (these days, most factory produced fretted instruments) have an adjustable metal rod called the truss rod imbedded within the neck, which counters the bending or bowing of the neck.  However, if underbowed enough even the truss rod will not properly straighten the neck. 

The load of the strings on the neck will cause the neck to bow, sometimes in such a way that the truss rod cannot correctly straighten the neck.  One problem common to stringed instruments is what’s often referred to as fretboard tongue lift (fbtl).  Often a neck will react differently to string tension throughout the neck itself.  Frequently the neck will remain relatively straight or will bow uniformly until the thickness of the neck gets substantially greater near the heal (the part of the neck attached to the body of the instrument).  Sometimes (typically on student grade instruments) the truss rod does not run the entire length of the neck, leaving the unreinforced portion of the neck more susceptible to bowing.  When fbtl occurs it typically occurs at approximately the 10^th fret causing the neck’s angle to drastically change (similar to a ski jump). 

There are multiple ways of repairing a bowed neck.  Which method used depends upon the severity of the problem.  Often times removing and regluing the fretboard will correct this problem.  Many factories use glues that creep or allow the glued parts to shift.  This usually happens when the glue joint is exposed to an excessively hot environment (such as a hot car on a summers day).  A second effective method of fixing a very badly bowed neck is to remove the fretboard, plane the neck straight, reinforce the instrument with an adjustable truss rod if it doesn’t already have one or even install one or more carbon fiber rods which stiffen the neck and help the instrument to resist future bowing.  Another common method of fixing a bowed neck is to plane the fretboard straight (requiring a refret on fretted instruments).  Yet another way of correcting a bowed neck on a fretted instrument is to refret the instrument with wider tang frets.  The tang is the subsurface part of the fret that actually embeds itself into the fretboard.  This is called compression refretting and may only correct a modestly bowed neck.  Lastly, if the bow or fbtl is subtle it may often be corrected by leveling the frets.

Broken or Damaged Bridge Plate/ Bridge Patch

Attached to the inside of the top of a flat top acoustic guitar is a thin piece of wood called the bridge plate (or bridge patch) that reinforces the top and protects the spruce from the ball ends of the strings. 

The most common type of damage sustained by the bridge plate is wear and tare from the ball ends.  If this is the case the original plate may be repaired if the damage is not too extensive.  We can do this by patching in new wood in the damaged area or by filling the damaged area with a mixture of cyano acrylate adhesive (aka: super glue) and hardwood dust.

Another common problem with the bridge plate is the development of a crack between the bridge pin holes.  This is typically caused by the top of the guitar warping from a lifting bridge or near by brace failure (braces on the underside of the top of the guitar coming loose from the top).  If the plate is cracked or broken it should be replaced.

Flat Top Acoustic Guitar Lifting Bridge

The bridge-top glue joint on a flat top acoustic guitar often fails.  This typically happens slowly over time and often is not noticed until the glue joint is severely open.  There are many factors in the failure of this glue joint.  One of the most common is undue stress put on the glue joint by top expansion and contraction due to extreme fluctuations in humidity.  Another is exposure to high temperatures (such as a guitar left in a car on a hot summer’s day).  Most glues used to construct factory built acoustic guitars today cannot withstand high temperatures, therefore highly stressed glue joints (such as the bridge, braces under the bridge and the fretboard) are the first to fail or creep.  If left unattended a lifting bridge will only get worse.  The main structural purpose of the bridge, beyond stabilizing the saddle, is to disperse the force of the strings as they pull up on the top of the guitar.  As a bridge lifts there is less mass dispersing the force of the strings and therefore the stress on the top becomes concentrated in an ever smaller area.  If left unattended long enough a lifting bridge will most likely eventually break the top across the pin holes, warp the top and the bridge itself can become too bowed to be planed flat requiring a bridge replacement rather than reglue.  There are two basic ways to repair a lifting bridge. 

The simpler approach is to rub glue under the lifting portion of the bridge and clamp down the bridge.  This repair does not always work and may only help a mildly lifting bridge.  Because old glue remains in the joint this repair is almost never a long term solution.  Often times manufacturers fully or partially glue bridges to the finish on the top of the instrument.  If this is the case rubbing glue under the bridge and clamping it will not work.

The second and most effective way to repair a lifting bridge is to remove the bridge, clean up and refit the bridge to the top and reglue it to the top of the guitar.  Although more expensive this is the preferred method of bridge repair for a repeat offender (a previously repaired bridge) or for a bridge that is warped and or badly lifting.

Closed/Hairline Cracks

The two primary causes for this type of crack are changes in climate and impacts with foreign objects.  When an instrument becomes too dry the wood shrinks as it loses its moisture causing, among other problems, cracks to develop in the body of solid wood acoustic instruments and finger/fret boards of all instruments.  Stringed instruments require a consistent humidity of 50-60 percent (measured by a hygrometer).  They also need to be kept as much as possible at a steady temperature because rapid changes in temperature will cause finish checking as well as cracks in wood.  Basically, treat your instrument as you would a child.  Don’t leave them in the car to bake or freeze and control either the climate of your house/studio or the environment inside the instruments case with a humidifying device such as a damp-it.  A damp sponge in a plastic bag with holes in it also works.

There are multiple methods for fixing closed cracks, the best of which is to glue the crack with wood or hide glue and clamp it closed.  Reinforcing the crack from the inside of the instrument with small diamond pieces of wood (called cross patches) is also a good idea to prevent the crack from redeveloping in the future.  Often times, though, this repair requires costly finish work to make the repair as close to invisible as possible. 

Another method of repair is to glue the crack with a cyanoacrylate adhesive (super glue and krazy glue come from this family of adhesives).  These glues serve the dual purpose of closing the crack and filling in the missing finish at the same time.  Though typically less expensive, the results of the c.a. repair are not always as visually subtle as the wood glue repair.  Cross patches are a good idea with this repair as well.

Finger/Fretboard Wear

The oils and dirt from a musician’s fingers build up on the strings and fingerboard of a stringed instrument in short order. As the instrument is played, this build up of gunk (often referred to as smut) acts like fine sandpaper slowly digging away at the typically unfinished wood of a finger/fretboard causing pits to form.  In order to avert this unnecessary wear, regularly clean and seal (with lemon oil or a wax such as butcher’s wax) your finger/fretboard and clean or replace your strings. 

Fretted instruments are especially affected by dirty strings.  Typical fretwire (18% nickel silver) is made softer than often thought for purposes regarding filing and pliability (fretwire must be able to conform to the radius of a fingerboard and be easily cut, filed and sanded).  Because of this, an instrument played often or one subjected to large amounts of dirt and oils will quickly develop worn frets.  This is rectified by a process often referred to as “dressing frets”.  The frets are filed or sanded until no pits exist, then they are recrowned and polished.  Typically an instrument undergoing this process requires a set up (adjustments in action and intonation) to compensate for the change in overall fret height.

Lifting Pickguard/ Cracks at Pickguard

Back in the day during an instrument’s assembly the major guitar manufacturers simply spread some solvent (such as acetone) on the back of a pickguard and slapped it on the unfinished top of the instrument.  They would then spray over the whole guitar with lacquer.  The acetone actually melted the plastic and the wood together making a strong bond.  So strong, in fact, that when the plastic shrank over the years (at a much faster rate than the spruce top of the guitar) the guard would pull the wood with it and crack the top around the pickguard.

In repairing a guitar with this problem the ideal approach is to remove the original guard, apply finish in the area where it was and substitute a new self-adhesive guard.  On occasion individuals wish to keep the instrument’s original pickguard.  In this case applying finish under the guard is still desirable, however the old guard may be reattached with rubber cement, which will allow the plastic to shrink without further damaging the top.  The rubber cement, however, will not keep a shriveled up and warped guard down.

Neck Reset

All stringed instruments are designed for a neck angle specific to that model instrument.  Therefore, when the neck angle is improper, the instrument will not play or sound as it was designed.  As a stringed instrument ages the string tension (over 150 pounds on a flat top acoustic steel string guitar) begins to actually change the shape of the instrument.  More specifically, the top of the instrument begins to sink in under and around the fingerboard tongue (the part of the finger/fretboard that extends past the neck and attaches to the top of the body).  Also, the sides around the neck block (where the neck and body join) pull in.  As this happens the guitar cannot be adjusted to play with ease.  As the neck angle worsens the saddle (on an acoustic flat top guitar, or the bridge on a mandolin, jazz guitar etc…) must be cut lower and lower to make the instrument playable.  Of course, if the neck angle becomes too poor, a bridge or saddle adjustment will not allow for proper playability. Also, many musicians and builders alike attribute a loss of volume and tone to a low saddle. 

In order to reset the neck angle, the neck is removed from the instrument.  Many traditionally built stringed instruments have a dove tail joint securing the neck to the body.  Also, a number of contemporary makers use neck joints that are secured with a bolt or series of bolts.  We remove a dovetailed neck joint or a straight mortise in tenon/bolt on neck joint by directing steam into the joint through a small hole in the fretboard drilled beneath the first fret over the body of the instrument.  We then cut the heel of the neck to change the angle then shim the mortise to tighten it up and reglue the neck.  We essentially have to rebuild the neck joint which is a time consuming task.  A new saddle must be made, then a set up follows to ensure that all the proper adjustments are made for optimal playability.