+|guitarheads.net|||||
+|black hard tail bridge||1|16.99|16.99|
+
+## Body ##
+
+I started out with a 1962 Stratocaster design file created in Alibre by
+user protomachinst6 on CNCzone.
+
+http://www.cnczone.com/forums/musical-instrument-design-and-construction/17659-cnc-32.html
+
+I originally hoped that I would be able to use FreeCAD to modify this design,
+but the STEP import process seemed to lose the ability to keep the various
+sub-assemblies oriented correctly relative to each other. Since Alibre has
+been replaced by Geomagic Design, I pulled down a 15-day trial version of
+that package to one of the Windows machines in the house, and (not
+surprisingly) it was able to read the file just fine. I was then able to
+export just the body and read that into FreeCAD, which was used for the
+remainder of the design work.
+
+Another interesting STEP file of the body from a 1962 strat drawn by Marc
+Erasmus is available on [GrabCAD](https://grabcad.com/library/62-strat-asm)
+and it appears at least one person has actually built a guitar using these
+files.
+
+To build the guitar body I want, the existing body design file was
+modified to eliminate the tremolo cut-out and rear cavity, to add screw holes
+for the hard-tail bridge, and to shift the electronics cavity from being
+front-open to being rear-accessible with the front just having 3 holes for
+the volume and tone control shafts and the slot and mounting screw holes
+needed for the pickup selector switch.
+
+The first attempt to cut the body on our CNC router failed, because a large
+delivery of building materials happened in the middle of the roughing pass,
+and I naively thought the router would be ok cutting for a while without
+me. Apparently, swarf jammed the bit up enough to cause the machine to lose
+steps and shut itself down. Unfortunately, when I attempted to restart the
+cut, something went horribly wrong and the roughing cutter put a deep gouge
+through much of the body of the guitar. I decided to call this attempt a
+bust, and look for more wood to start over with.
+
+## Wiring ##
+
+A standard strat has a volume control, 2 tone controls, and a 5-way pickup
+selector. The pickup selector allows neck, neck+middle, middle,
+middle+bridge, and bridge as choices, with the combinations formed by
+putting the two selected pickups in parallel. The first tone knob controls
+the neck and middle pickups, the second controls the bridge pickup.
+
+After lots of discussion with Robert and listening to many demo videos, the
+only significant change to this I decided to make is to use a push-pull switch
+variant of the second tone control, wiring it to allow phase reversing the
+middle pickup. Phase reversing one pickup of a blended pair yields a "nasal"
+or "biting" tone. Here is one of the
+[clearest demo videos](https://www.youtube.com/watch?v=VIBHg4kwl2k)
+I found of this effect. What I like about this option is that it gives what
+sounds to me like an old-school blues kind of tone.
+
+The other minor tweak I'm considering is "treble compensation" on the volume
+control, which DiMarzio shows in some of their wiring diagrams. The idea is
+to compensate for the usual loss of treble content when turning down the
+volume on the guitar. It consists of an additional 560pF capacitor and 300k
+resistor in parallel between the hot and wiper terminals on the volume
+control. This may or may not seem necessary once we have the guitar together.
+
+## Artifacts ##
+
+The following files are licensed under a [Creative Commons Attribution 4.0
+International License](http://creativecommons.org/licenses/by/4.0/):
+
+* [FreeCAD](http://www.freecadweb.org/) design file for
+ [guitar body](guitarbody.fcstd)
+