Between these photos and instructions and those posted in the 'Railway' Jazz Bass Guitar build, one can get a fairly good idea of the processes in the construction of this type of Bass Guitar.
Principles here can generally be applied to any solid body Bass Guitar build and only modifications and adjustments must be made for variations in hardware, number of strings etc.
Canadian Maple was selected as Maple or Ash are the traditional woods used by Fender in the construction of Jazz & Precision Style Bass Guitars. Here the wood is sent through a planer in order to remove surface scuff marks and defects as well as to bring it down to near the thickness of the finished body. Additional wood is removed by sanding but then again built up by the layers of finish.
The wood planed (above) is cut to size and glued together taking into consideration the end grain orientation. One piece wood (unjoined bodies) can be found but this sized planks come at a premium price and may be subject to greater warping. The sides of the wooden planks having been make perfectly flat by passing them through a jointer. Sides can just be glued and clamped or dowels and biscuits can be used to reinforce the joint. Usually the upper and lower horns of a guitar will differ in length and wood can be conserved by cutting the two sides to be joined to different lengths.
The Fiberboard template placed on top of the Maple Body Blank onto which the pattern will be traced.
Here the body is sanded with a dedicated surface drum sander. This can be easily accomplished by hand using anything from a block and loose sandpaper to a variety of portable hand sanders.
The edges are sanded on an oscillating spindle sander making them square to the faces. Again, this can be accomplished by the same hand sanders listed above. A piece of sandpaper wrapped around various diameter items, broom handle, tin can etc., can reach the inside of various curves.
An initial relief is given to the square edges with a roundover bit. A 1/2" roundover router bit is usually sufficient to accomplish this. This just makes work faster. Hand tools such as rasps, files, planes and spoke shaves can accomplish the same. Be cautious when working around the area where the neck pocket will be placed.
Here templates of jigs of pick-ups are placed onto the bass body indicating their placement. The straight edge template router bit's upper bearing follows the outline guiding the router & cutter in cutting out the pick-up's cavity. Here there is a home made template lying flat on the body. It was made by tracing the pick-up onto some scrap wallboard and cutting out with drills, jig saw, utility knives or files. Use whatever works. Smooth with sandpaper as an accurate jig will give the tightest and most professional looking cut. This is important if there is no pickguard used. A pickguard will hide errors. Standing perpendicular to the body on top of the wooden template is a plexiglas template. Both accomplish the same result.
More severe contours can be cut into the body using a variety of tools such as an angle grinder with a carbide wheel, micro razor rasps and traditional wooden rasps. Again, planes, spoke shaves and electric hand drills with sanding discs can also accomplish the job. Use what is at hand.
A variety of sanders are shown in the background starting with (left to right) a three headed contour sander, a variable oscillating rotary sander, a 1/4 sandpaper sheet palm sander, a hand drill with a disc sander attachement and finally a portable belt sander. A pleasant afternoon sanding the body by hand will also yield great results. Sand with (not against) the grain pattern and work with progressively finer grits from 80 if necessary, then 100. 120, 180 and 220. Any finer grits will polish the wood and make it too smooth for the primer to take. A damp cloth can be used to wipe down the body between sandpaper grits to remove the dust and also to slightly raise the grain. The next finer grit of sandpaper will shear off the raised grain and the final result will be smoother than with just straight sanding. Make sure the wood is perfectly dry especially if the finish will be an oil or spirit based finish as opposed to a water based finish.
Two Forstner bits lie on the left side of the photo.
Forstner Bits (think of large flat bottomed drills) lie on top of body. Forster bit diameters are chosen depending on diameter of of the cavity you wish to cut. The idea is this: In order to cut out a cavity in hardwood, much of the preliminary work can be done by drilling out the wood. The drill press is ideal for this as it is fast and stops can be set for accurate depths. One the majority of the wood is removed, the remainder can be removed with a straight cut template bit on a router. The drill press does the majority of the work and the router cleans up what the forstner bits have left behind. This places less stress as well as wear and tear on both the router motor & bearings as well as the bit.
A fiberboard (masonite) template for the cavity desired is attached to the body with double sided sticky tape. The router equipped with a straight template bit can now follow the template and "square up" the hole left by the forstner bits.
This larger square cavity is hidden by the pickguard and therefore is easier and quicker to cut than the bridge pickup cavity which is the exact shape of the pickup itself. This also allows a choice of pickup styles to be placed in this location without modification. An in-line Jazz pickup or a split Precision bass pickup can be installed as desired or requested.
The square cavity for the pick-up is shown after cleaning out with the straight edge router template bit which can be seen in the router on the upper right.
Pick-up & tailpiece router templates are shown to see how things are coming together. On the right a template can be seen on a scrap piece of wood used to test a cut.
These previous two bodies have been routed for two Jazz style in-line Pickups
In this photo and the two that follow the body differs as the upper pickup being hidden by the pickguard will not be visable. For this reason the accurate pickup shape is not bothered with at the neck location but only cut into the body at the visible bridge location.
The theory behind rubbing out a finish is that progressively finer abrasives produce progressively finer scratches in the clearcoat finish. Each microscopic scratch added acts like a facet in a diamond and reflects light. As the scratches have been applied in all directions, light is reflected off in all directions giving the finish a superior shine or gloss. Final sheen and protection can be achieved using fine wood wax or automotive finishes. Caution!!! Do not use products which contain silicone as it make any touch up or refinishing very difficult.
(2) TPI or Teeth Per Inch. Band saw blades are measured with Teeth Per Inch where the more TPI gives a finer but less aggressive cut and conversely less TPI cuts more quickly but is not as smooth. Other considerations on a choosing a band saw blade are 'rake' , 'off-set' and width of blade.
(3) Tack Cloth - is a cloth saturated with a substance that makes them sticky or tacky. They can be solvent/oil based or water based materials and the type of cloth should be compatible with the finish you are using. ie. using a solvent/oil based cloth on a project finished with water based lacquer will be counterproductive. The oily residue will reject the water finish as oil and water don't mix. Solvent/oil based tack cloths are the most common and found in most hardware or home improvement centers. Water based tack cloths are less commonly available - one brand name was 'Chix' cloths.
(4) HVLP - High Volume Low Pressure is a spray system which uses single to triple stage turbines instead of an air compressor to deliver a lower pressure to move the paint onto the surface being finished. The system is much quieter and delivers the paint with less overspray. Overspray is the paint which is wasted missing the targeted surface and as it is not sprayed into the air and wasted it is is more economical and environmentally friendly.
(5) MicroMesh is a 3M product of ultra-fine abrasives bonded to a cloth backing. They are so fine that they are used to polish out scratches from plexiglas visors and helecopter bubble windows.