In order to string up the guitar and begin the mechanical setup by shimming the bridge to set the playing action, I needed to make and slot a nut. The nut on the Red Special, as with other guitars that have a zero fret is more of a string guide which limits gross sideways movement of the strings than a conventional nut which acts as one node for each vibrating string. I have previously made several Bakelite nuts for myself and others but I have never documented the entire process (which is relatively complicated for the size and function of the piece) in a single narrative, so this article addresses that shortfall.
While the width of the Brian May Red Special fretboard at the nut position is known (1 13/16″, 46.0 mm), the thickness and overall height of the nut is not known (to me). Therefore, some educated guesswork was required. I have always wondered what influenced Brian and Harold to choose the particular dimensions on the guitar; my personal theory on the neck is that they wanted the Red Special to have the feel of a classical acoustic guitar which generally have wider necks: 1 13/16″ being the next most common after 1 3/4″ (44.5 mm) and 1 11/16″ (42.9 mm). As an aside, Brian has commented in the past that he made a mistake when carving the neck and didn’t subtract the fretboard thickness, hence why it is so thick. I don’t accept this explanation because, while the neck is certainly thicker than the most popular electric guitars in the early 1960s, it is certainly not 4.5 mm to 1/4″ (6.4 mm) thicker which are the thicknesses of the fretboard at the side and at the crown near the nut. I think that Brian and Harold made a conscious decision to make a thick neck simply because Brian has quite large hands and long fingers and preferred playing the thicker neck of an acoustic guitar which fills the hand better compared to a Fender Stratocaster or Telecaster, or Gibson Les Paul/ES355 models.
One factor might have influenced the choice of 1 13/16″ is that it makes the string spacing maths easy: general guidance is that the centreline of the top and bottom E strings on a six string guitar should be 1/8″ (3.18 mm) from each edge. 1 13/16″ is equal to 29/16″ written as an improper fraction. Subtracting 2/16″ for each outer E string (i.e. 2 x 2/16″) leaves 25/16″ to space the other four strings, i.e. five gaps between each string centreline of 5/16″ (7.94 mm).
I initially assumed that the overall height of the nut was 3/8″ (9.5 mm) but this looked too high when offered up to the guitar so I reduced it to 11/32″ (8.7 mm). Determining the likely thickness is relatively straightforward because most items made of Bakelite seem to be 1/8″ thick. Some relatively recent close up photographs (e.g. from Paul Balmer’s Haynes Manual) show that the Bakelite is the brown marbled or mottled type which is easy to source.
Sourcing and Preparing Bakelite
There always seems to be a large variety of vintage items made from brown Bakelite listed on eBay. Some items are aesthetically pleasing and/or have historical value and, as such, are too expensive and too good to use as stock material (e.g. vintage radios). However, I have found that vintage Ormond E1022 hairdryers are still plentiful and can be bought relatively cheaply. The cases are also made of brown Bakelite, can be cut easily with a rotary multitool and cutting disc and yield a reasonable quantity of nuts. I found that the sheet thickness in the raised sections in the lid is nearer to 9/64″ (3.5 mm) so I used this in preference because I perceive that the nut on the original Brian May Red Special is slightly thicker than 1/8″.
The CNC cut only takes around two minutes per nut (1000 mm/min XY feed rate, 0.25 mm depth per pass using a 2.0 mm diameter, single flute solid carbide end mill). This process is illustrated in the short video attached to this post. I generally use double sided adhesive tape for holding down the material to a 12 mm thick MDF spoil board on the machine bed. The second Bakelite case lid was warped so I screwed it down and only cut from the centre of the piece. In an ingenious economy of design, Brian cut a rebate in the front face of the nut to hold the back of the plastic truss rod bolt cover captive, meaning only one screw is required to secure it in place. I estimated this rebate to be 1/16″ deep. I estimate the plastic used in the truss rod bolt cover and the pickup surrounds is nominally 1/16″ (1.6 mm) thick so I prepare mine by milling down 2.0 mm thick perspex and manually polishing it. This generally leaves the plastic slightly over-thicknessed at 1.65 to 1.75 mm so I designed the rebate to be 1.75 mm high to allow enough clearance for some cutting error.
Although general guidance is that the centreline of the top and bottom E strings on a six string guitar should be 1/8″ (3.18 mm) from each edge, it is clear from photographs and experience of people who have played the original Red Special that the strings are closer to the edge of the fretboard than is typical. 3/32″ (2.38 mm) seems too close to me so I chose 7/64″ (2.78 mm) as a sensible compromise. Since the neck and fretboard width outturned around 44.8 mm at the nut on my build, I made my nut to this dimension so it was flush with the edges, but I still cut the top and bottom E slots to situate the top and bottom E strings the desired measurement from the edge of the fretboard. This yields the five string spacings to be 7.85 mm instead of 7.94 mm (5/16″). I decided to slot the nut off the guitar for various reasons, but principally if I made a mistake or was not satisfied with the spacing, I could remove the nut easily and try again. For this reason, I used my damaged test neck as a jig. I cut a section of PTFE sheet, drilled some slots in it and mounted it on the upper surface of the neck, in front of the nut. I used a set of StewMac nut slotting files to file the nut slots. The nut pictured is an early attempt with an unsatisfactory spacing of the E string slots so I made another. Bakelite is quite brittle so it is a good idea to slightly round off the top edges with abrasive paper to reduce the likelihood of chip out when filing the string slots. It is also more aesthetically pleasing.
Part 59: Initial Setup (Setting the Playing Action and Pickup Installation)
Part 57: Control Cavity Copper Foil Shielding