Important Features of the Neck Jig

The Apollo Neck Jig uses a unique process to fit and position the neck during the neck and pot assembly process.  It ensures a perfect fit by creating a micro shim between the neck and pot components at the final assembly stage.  The micro shim ensures an intimate microscopic fit between all components.  In addition to a perfect fit, it also ensures that the action will be correct after tightening up the strings.

It is generally accepted in the banjo world that the neck is an important part of the banjo sound system.  This means that the neck vibrations must be transmitted across the interface between the neck and the pot assembly.  It goes without saying that a good fit would be better than a bad fit from the sound transmission standpoint.

There are two major issues a banjo craftsman must deal with when mounting the neck to the pot assembly.  One is creating the proper fit, and the other is winding up with the neck being in the proper position without resorting to distorting the neck or rim using the truss rod or coordinator rods.  Or worse yet, shimming the neck to tilt the neck or elongating the screw holes to raise or lower the neck in order to get the desired string action etc.

The neck can not be properly fit to the pot assembly prior to applying the finish because the thickness or final profile of the coating can not be predicted.  In addition, the upper part of the neck interface must rest on both the tone-ring and the rim.  These two are not normally the same diameter before, and even more variable after the lacquer coating is applied.  The lower surface of the neck fits on the lower portion of the rim which is about ¼ inch smaller in diameter than the tone-ring and rim.  Getting all these surfaces to fit properly is not possible using present methods.  In addition to the correct fit, you also have to deal with the desired action of the strings on both ends of the neck, as well as the bridge height, head depression, and neck deflection after tightening the strings.

Research has shown that most banjo builders have not taken the above issues seriously.  There is clear evidence that “close enough” is just that.  I have found no evidence that anyone has successfully produced, or attempted to produce, an intimate fitting interface between the three different surfaces.  A precision gauge was built to measure the relationship of the neck to the top of the head on banjos.  Measurements collected from numerous banjos, including some major brand names, found them to vary considerably, even within the same manufacturers.

The Apollo Neck Jig not only addresses the neck and pot assembly interface, it also addresses the desired results after the banjo is assembled.  A mathematical model is used for entering the desired end results and it calculates all the correct settings for the Neck Jig.  The Neck Jig can be used for both dry fitting before the finish is applied as well as the final assembly.

The Apollo Jig not only produces a perfect fit between the neck and pot assembly, the strings will be exactly where you want them to be.

Coy Willis
Apollo Engineering