I'm willing to give this a shot, but am a little antsy about diving in without careful instructions. I've searched for a link, but mostly found threads involving people arguing about whether/how to properly add a shim. Can anyone supply a reliable link about shimming to raise the action? Thanks in advance!
It is a simple procedure.
1. Loosen the strings.
2. Remove strings from peghead. This is optional. Quite often it can be skipped.
3. Remove neck bolts. Alternate star or X pattern like automobile lug nuts.
4. Gently remove the neck from the body. Some pockets are tighter than others. If it is difficult to remove the correct motion is to push the headstock in forward or backward (neck to strings) as opposed to side to side (bass to treble).
5. Make shim. Business cards are handy and readily available. Cut a card 3/16-1/4" wide by the length of the pocket. If the neck has rounded corners then approximate the corners on the edges of the shim if the shim is to be placed at the end of the neck.
6. Increasing the neck angle: place the shim at the end of the neck pocket south of the screw holes. This will tilt the headstock away from the bridge. The effect is to bring the fingerboard closer to the strings.
OR
7. Decrease the neck angle: Place the shim at the headstock end of the pocket north of the screw holes. This will tilt the headstock toward the bridge. The effect is to place the fingerboard farther away from the strings.
N.B. The results of steps six and seven are similar to tightening a truss rod (shim at body end of the pocket) or loosening the truss rod (shim at the headstock end of the pocket).
8. Replace the screws. The caveat here is to be careful with the internal threads in the wood. Place the screw in the hole and turn it CCW until it thumps into place. The beginning of the threads on the screw have found the beginning of threads in the wood. The screw will rise and fall. You will feel it. Now reverse direction and turn the screw CW. Use a star or X pattern. I usually leave the screws a bit loose before driving everything home. This assures that everything is lined up the way it is supposed to be. That entails replacing the strings before tightening the bolts. Choice is yours.
9. Replace strings if necessary and tune to pitch.
10. Decide if this is where you want the neck to be. This may require a setup. But before the setup is performed it is usually easy to tell if this adjustment is correct. If the neck should be moved in the same direction add a shim. If the movement is more than is desired, use a thinner material.
Anytime shims are discussed there will be a debate. One of the debates centers on shim material. Recommendations as to material selection are as many as the stars in the sky. Many will claim sonic excellence of one material over the other. It probably does make a difference but the real question is what kind of meter will be needed to measure the difference. If someone has a preference for one material over another, then by all means use that material. I like business card stock. It's paper. It's made from wood. I have a huge stack of them from people whose addresses have made their way into the electronic contact list so I don't have to cut up my own.
The second debate is over a shim size. Some use a thin strip of material. Others swear by a full pocket shim. The full pocket shim is exactly what it sounds like. It covers the entire bottom of the pocket. The argument usually made is that the full pocket shim promotes better sustain. Maybe it does. Refer to the meter question above. The best argument for the full pocket shim revolves around the thinking that over a long period of time the neck can develop an anomaly in the fingerboard. It is thought that if the bolts are driven over tightly that eventually the neck will bend over or around the shim. If the shim is at the base of the neck it will develop a "ski jump" or if it is at the headstock end it will develop a hump. Like the Mythbusters, it is plausible. But it is usually seen where an unusually thick shim. By unusually thick, think a sixteenth of an inch. It is undeniable that this large shim will offer better support than a penny or a thick tooth from the end of a comb. However, a full pocket shim is a lot of work. It is typically constructed from a piece of lumber that is the same as the body or the neck with the grain oriented in the same direction. Typically it will be as thick as the proper paper shim on the business end and taper to literally nothing at the opposite end. It is almost a necessity to have access to a stationary belt sander to perform create this part. And having experience in woodworking is a must or all that will result from the exercise is frustration and a pile of tapered toothpicks.
Most people make their shims with a slim piece of business card.
