Fitting the Body & Neck Pocket

Fitting the traced guitar body to the neck pocket is a multi-step process:

Step 1

Move the guitar along the Y-axis to shift the bottom of the lower horn cutout nominally in line with the 21st fret.

This will typically result in a visible mis-match between the traced data and the Standard Guitar CADD data around the neck pocket.

We'll fix that next.

Step 2

Create an attractive transition between the upper horn and the neck pocket

In this case, we're going to start with an incomplete fillet.

Draw a 3-point circle (a) tangent to the upper horn edge, (b) tanget to a line parallel to the top of the neck pocket offset 3/32" (0.094"), and (c) through the left corner of the neck pocket.

Trim as required.

Now is a good time to check the radius of that incomplete fillet.

Our target minimum radius of any internal edge to be cut with a 1/2" DIA router bit is 5/16" (or 0.3125"). This provides for our tool offset (0.250" radius) plus our 0.030" roughing offset plus an additional 0.032" for our desired minimum radius for our AXYZ CNC router tool paths.

The diameter of the circle shown for our first pass upper horn transition is 0.4117" which is greater than 0.313".

We are therefore good to move on to the lower horn transition...

Step 3

Create an attractive transition between the lower horn and neck pocket nominally in line with the 21st fret.

The process is relatively straight-forward:

Trim off the traced transition arc(s) connecting the upper horn to the neck pocket.
Draw an orthogonal line from the 21st fret toward the lower horn.
Extend the edge of the lower horn down to the line extending from the 21st fret
Use the Draw-> Circle -> Tan, Tan, Tan command to draw a circle tangent to the lower horn edge, the 21st fret, and the neck pocket (as shown)
Trim as required and delete the 21st fret extension line
Again, confirm that the resulting radius exceeds our 0.313" min. target radius. As this radius happens to clock in greater than 7/8", we are good to go.

Now, let's have a look...

Zoom out,turn off some layers (to reduce the clutter), turn on layers containing the visible hardware (e.g., bridge & saddles, humbuckers & mounting rings, the original Rocket knobs) and have a look at the results:

Not bad... not bad at all.

Now let's fine tune the transitions...

Where these two new arcs from the horns intersect the neck pocket—

the body-to-neck pocket transitions, if you will—

the width will taper to zero and the wood will break off.

We want to control that break.

A good target width (nominally, the diameter of the fillet) of these body-to-neck pocket transition relief cuts is ~1/8" (diameter)

Use the Draw-> Circle -> Tan-Tan-Radius and then trim them to create two fillets with a nominal radius of 1/16" (0.063").

Next...

There are two "hard stops" (i.e., 90° corners) on the top end of the neck pocket. Since these corners are external, there is no minimum radius to worry about. So, a couple of small (~1/32"R) fillets will keep the cutter moving.

First we need to duplicate the top and right side of the neck pocket edges as this will be needed to create the complete outside edge profile of the body. #HoorayNamedLayers

We can use either the Modify -> Fillet or Draw -> Tan-Tan_Radius to create the small, bottom-side fillets on the end of the neck. #DesignersChoice

Trim everything up and then use the Modify -> Join command to close out the neck/body geometry.

Back to "Patrick Star" Guitar Development Home

Back One Page: Importing the Standard Guitar Data Set

Next Page: Modifying the Traced Shape: "The Mercury"

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