STEP BY STEP - 7
ASSEMBLE THE GUITAR - INSTALL NECK
This is one of the most critical steps in the entire process of assembling the guitar. The entire geometry of the guitar depends on it. This is a task best learned through experience, but several pointers can be mentioned. Most of the adjustment is done to the edges of the heel of the neck where it meets the body. (I call these the "cheeks" of the heel.) If you remove wood from one side the neck will move to one side or the other relative to the center line of the guitar. If one removes more material from the heel near the heel cap the neck will angle back from the plane of the top and conversely if one removes more material near the fingerboard the neck will angle forward relative to the plane of the top.
Adjust any of the above as necessary.
I try very hard to have all of the neck fitting done (or very very close) before I finish the neck and even before I attach the fingerboard. This makes access to the cheeks of the heel much easier. I strive to have the centering of the neck accurate to within 1/64th of an inch - and in no case more than 1/32" off center. I try to have the neck angle back so that a straightedge laid on the fingerboard will be 12/32" above the top at the point of the saddle. this allows me to make a bridge that is 12/32" high and still have a reasonable protrusion of the saddle above the bridge.
One technique that should be learned is what I call slip fitting a neck. Once the basic angles are correct the cheeks of the heel must fit the body perfectly - any failure here is very visible and will make the guitar hard to sell. The technique is this: Hold the neck in place with a strip of sandpaper (I use 150 grit) between the neck and the body, with the grit touching the cheeks of the heel. Applying some pressure to the neck, carefully pull the sandpaper out from between the cheeks and the body (one side at a time_ This will essentially scribe the heel to the body and result in a factory perfect fit. If the body is finished I put a strip of thin low tack masking tape between the body and the heel to avoid scratching the finish.
Once the neck is properly located one must make sure that the dovetail is tight - the joint should be tight enough to hold string tension without glue. It is rather difficult to describe this - but if there is any motion in the neck/heel, the location of that motion (and the amount of motion) should tell you where to add shims or remove wood. The object is a tight fit when the neck is clamped fully into the box. I generally use mahogany veneer to make any shims - it is a compatible wood (i.e. it is the same wood) and it is easy to work. One advantage of using shims is that if you remove too much wood from a shim it is easy to start over.
Verify location of fingerboard on top, mask and remove lacquer.
I find that it is easiest to get a good finish on the body if I do not mask off the area where the fingerboard will be glued on. So, once the neck is fully fitted I carefully mask off the space and remove the lacquer. I generally let the lacquer run under the fingerboard perhaps 1/16" so as to ensure a good looking joint. I use paint stripper to remove the lacquer.
Recheck fit of neck - several times.
The fit of the neck is critical - both structurally and cosmetically - nothing flags poor workmanship so easily as a poorly fitting neck. Here is a good place for the old adage of "measure twice, cut once" - although here it would be "Glue once."
Prepare clamps and cauls.
Not much to say here - I use a large C clamp to hold the neck in and two small C clamps to hold down the fingerboard extension. A caul on the fingerboard will take care of that side and one on the back of the body to protect the finish. and one inside the top to prevent crushing the braces there.
Glue in Neck and fingerboard extension.
I use Titebond here. I need more time than hide glue allows, Titebond works well and can be undone with steam if that ever becomes necessary.
Clean up all glue squeeze out.
I use wet (and then dry) paper towels for this. A small 6" ruler helps to get the towel (rag) into the tight corners.
Let glue dry for 24 hours.
This is easy enough.
Verify correct location of neck.
Hopefully all is well.
Other than size, the critical issue here is no cracks or checking. Look carefully. Woods other than ebony are perfectly acceptable - I use Brazilian Rosewood from time to time.
Surface bottom to smooth.
I use a flat top so the bridge can be flat. If you decide to use a domed top the bridge will have to be shaped to fit. This is generally done after the bridge is shaped but the progression is not critical.
Rough cut profile.
I trim roughly with a bandsaw. I save the scraps - ebony dust is sometimes necessary for various tasks and the scraps can be used to make it.
Trim blank to profile on shaper.
I use a shaper because I have one and it is fast. You can easily do this by other means, including hand tools. symmetry is important (if your bridge is intended to be symmetrical - mine is). The easy way to achieve this on a shaper is to have a one sided jig. I cut one side - flip it over and cut the other side. Voila - a symmetrical bridge profile. A router table will work equally well.
Band saw rough cut for ears of bridge.
I use the band saw to roughly scoop out the ears (wings) of the bridge.
Thickness ears on drum sander.
I have a small drum sander (built into my lathe) which does this quickly and easily. Most any method will do.
Sand top profile on bridge blank.
The top of my bridge is not flat - it is curved to (more or less) match the arch of the fingerboard. It also tapers from front (about 12/32") to back (about 1/8"). I do this first on a belt sander to rough shape and then by hand - first with a rasp and then with hard or relatively hard sanding blocks to avoid rounding over the edges which are intended to be sharp (mainly the point where the curve of the ears meets the surface of the top of the bridge.
Finish sand bridge.
I generally sand ebony to a 400 or 600 grit finish.
9. Locate bridge on top - check it several times.
Check for distance, centering and perpendicular to centerline of
Again, measure twice, cut once. Be very careful at this stage.
I speak from experience - I have several times placed a bridge for a 14
fret guitar in the location for a 12 fret guitar - requiring a whole new
Again, measure twice, cut once. Be very careful at this stage. I speak from experience - I have several times placed a bridge for a 14 fret guitar in the location for a 12 fret guitar - requiring a whole new top.
Scribe finish around bridge.
I use an exacto knife with a # 11 blade. I use a fresh one every time and I heat the blade in a propane torch before cutting the finish - it helps to avoid any chipping. Here is another area where precision is important and lack of it will be glaringly obvious.
Remove finish from top under bridge.
I use paint remover - followed by very careful use of a chisel to remove all the finish up to the scribe line. I then sand the bare wood of the top carefully to ensure a clean surface for gluing. Some people use a chisel and scrape the finish away. Others use a mask placed on the top before finishing, which is then removed prior to gluing. All of these methods work well- I am just used to doing it one way and see no need to change.
Locate bridge pin holes.
Placing the bridge on the top in its "divot" in the finish, I hold it securely in place with masking tape and lay out the placement of the bridge pin holes. I place the pins on a semi circular arch so that all 6 holes are not on the same grain line, which I think may help to reduce bridge splitting. Martin has used 6 in a line for a long time with no great problem so probably either method will do. Others use a straight line that parallels the slanted saddle, which avoids the splitting issue and keeps the string angle off the back of the saddle uniform for every string. This does make intuitive sense, although I doubt that it is a critical issue either way.
A word about string spacing. Most makers will space the bridge pin holes evenly. I do. An argument can be made for a proportional spacing which allows for the different thickness of the strings (i.e. space so that the gap between strings is equal, instead of having the centerline of each string being equally spaced.) As I say, I use equal spacing based on the centerlines - use your own judgment.
Drill bridge pin holes.
I then take the bridge off the top and drill the holes (with a 3/16" brad point drill). I drill them at a slightly back leaning angle - mostly a cosmetic thing, I believe. I then place the bridge back on the top and drill two of the holes through to top, and ream them with a tapered reamer. I then use tapered poly plastic locating pins to ensure that the bridge will not move when I apply gluing pressure.
Glue on bridge.
These days I glue on bridges in a two step process. I use hot hide glue. Because this has such a short open working time I begin with a vacuum clamping jig - for about 2 minutes. Then I switch to metal C - clamps. The trick with these clamps is to make a caul for the inside which spans the braces and gives a good surface for the clamp. Also a caul for the top of the bridge.
Locate and cut slot for saddle.
Here again, measure twice, cut once. I measure twice the distance from the nut to the middle of the 12th fret and add 1/16" on the treble side and 3/16" on the base. This gives a good location for proper intonation. I use a 1/8" wide saddle and can easily shape the top of the saddle for good intonation.
I cut the saddle slot with a laminate trimmer (a small router). These are powerful enough to do the job cleanly and with some speed. I have a jig which I made which holds the router evenly above the top and which and be carefully placed so that the slot is in the right place. As you can see from the photo, it is a relatively simple jig.
Drill out and ream bridge pin holes.
I use a tapered reamer designed for bridge pins - it works quickly and easily and ensures a good fit. The pin (with the string in place) should fit snugly but not tight - you do not want to create a wedging action which may split the bridge.
17. Cut slots in bridge for strings.
I use a saber saw blade to rough cut these slots and final shape them with
a needle file. They should be properly located - i.e. evenly
spaced and facing directly forward.
They should be properly located - i.e. evenly spaced and facing directly forward.
Here you will find out if your fret installation was accurate. It is essential that the tops of the frets all be perfectly even. Without elaborate equipment it is difficult to achieve this, so I always lightly dress the tops of my frets to ensure that they are perfect. Once this is done the frets must be re-rounded and the ends carefully shaped. As fret work can be the subject of a book in itself, I will not go into great detail here.
Final sand and polish of fingerboard, including light oiling.
After final shaping of the frets the entire fingerboard is polished with 600 or 1000 grit sandpaper to give a good polish. The board is then lightly oied with a good lemon oil. It need not be soaked - just a light rub down and a repolish with 0000 steel wool.
Make and install saddle in bridge.
I make my saddle from 1/8" unbleached bone. Bone is nice and hard so it is durable and gives the sound I like (a nice bright sound) Unbleached bone is harder than the bleached and looks better, to my eye.
First I cut the saddle to fit tightly in the slot. I like it to be tight enough that I can grab the saddle and lift the body of the guitar off the bench. However, it must be loose enough so that it seats well on the bottom of the slot. Work slowly and carefully - a few thousands of an inch will make the difference.. Next shape the top. After doing this for 35 years I can pretty much eyeball the correct height. I curve to top of the saddle to match the arch of the fingerboard.
Then I try to compensate the top of the saddle for best intonation. A good place is to place the high "E": string near the front of the 1/8" saddle, the "B" string near the rear of the saddle and the "G" through "E" strings moving gradually from the front of the saddle to the back. Once the guitar is strung up and tuned you can check for proper intonation and make any necessary adjustments.
Drill out end pin hole, ream to proper taper and size, install end
If you have a tapered reamer with the same taper as your pin, this is an easy job.
Check polish of peghead and install tuners.
The peghead is one of the most visible parts of the guitar so make sure your finish work is good. The holes for the tuning machines may have to be reamed to allow a good fit. Again, use care - the fit should be slightly snug and the tuner should not "rattle around" in its hole.
Make and install nut.
I use unbleached bone for my nuts. I like the look and it is very hard - an important factor here. There are several steps to follow here.
Step 1: The "nut slot" - i.e. the space between the end of the fingerboard and the peghead veneer must be clean and the bottom flat. (Martin uses a sloped bottom for their nuts, but the idea is the same - the place where the nut will go must be clean and the bone must seat cleanly and firmly.
Step 2: The nut must be cut to length. I start with simple pencil markings and cut close to length. I then file or sand to final length. As my neck is slightly curved there I use a sanding drum in my oscillating spindle sander. this is fast but other methods work equally well. This is another of those cosmetic areas that people tend to notice so get it nice and neat.
Step 3: Shape the top of the nut. I try to have the top of the nut mirror the arch of the fingerboard. The easiest way to do this is to sand a pencil so that it is flat along the length, lay this on the frets and mark the nut. I then sand the nut to this profile on a disc sander and finalize the shape with a file and sandpaper (to about a 220 grit.). I then polish the whole thing on a buffing wheel with very fine compound. With very little effort you can make a piece of bone look like plastic - Oh Joy!!
Step 4: Space the nut slots. There are tools out there specifically to assist with this task. One is made by Stewart MacDonald and the other can be found on Frank Ford's site - here. http://www.frets.com/FRETSPages/Luthier/Tools/NutRule/nutrule.html. Both of these tools give a proportional spacing - i.e. the gaps between the strings are equal but the space between the centers of the strings are different. This seems to be the technique used by most builders and repair shops these days.
Step 5: Cut the slots; I first make a saw cut with a very fine saw (about .010") to accurately locate the center of each slot. I then widen and deepen them with nut files. These files, widely available from supply houses for the guitar business are really essential. While the job can be done with just a needle file, it is much more tedious and less accurate.
Step 6: Final adjust the dept of slots. My method of doing this is fairly simple and relies on one fairly intuitive (to me) fact - that the nut is really no more than another fret. So, I take a very thin straight edge (I use a .010 saw blade and use the non-tooth edge) that is long enough to span the nut and the first two frets. If the straight edge is higher than the frets, and if you gently pull it back out of the nut slot it will fall down to the fret and make a quiet click sound. As the slot gets closer to the correct depth the "click" will be softer and softer. I leave the slot just a tiny bit high - and this is a matter of "feel".
Clean interior of guitar.
I use a combination of a vacuum and an air gun to completely clean out the inside of the guitar.
Make, sign and install label.
Self explanatory. I use 3M #77 spray adhesive.
String up and tune guitar.
No instructions should be needed.
This website and all of its
content, text and images are copyright ©1997-2011 by Charles A. Hoffman.
All rights reserved.
This website and all of its content, text and images are copyright ©1997-2011 by Charles A. Hoffman. All rights reserved.
2219 East Franklin Ave.
Minneapolis, MN. 55404