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Brian May Red Special Guitar and Equipment Information

Tag: Stepcraft CNC

Brian May Red Special Roller Bridge CNC Milling

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Brian May made the unique design of roller bridge for his original Red Special guitar from a piece of aluminium bar using hand tools. In my latest YouTube video I illustrate the process of making this intricate item by CNC milling using a hobby class CNC machine, in my case a 2016 model Stepcraft 2/840. The main sequences are all speeded up and the longer sections are considerably shortened so that they are only illustrative of the full process. The background music is Brian’s guitar solo from Queen: A Night at The Odeon.

I prepared a section of 6082 T6 aluminium bar to 84 x 16 x 10 mm using a hacksaw and abrasive paper and mounted this onto a levelled, square section of aluminium plate on my CNC machine bed using cyanoacrylate superglue. I then use three single fluted solid carbide cutters to mill the roller bridge: a 3 mm one for the thicknessing operations then a 2 mm cutter for the outline and roundover toolpath and cutting out the individual blocks and finally a 0.8 mm cutter for milling the roller axle channels (see note below).

I designed the general appearance such as the edge roundovers to resemble the Guyton Red Special bridge with the exception that the channels cut to accommodate the 1/32″ (0.8 mm) diameter axles of the roller saddles are drilled to 0.8 mm deep on those pieces whereas I only milled them to half-depth (0.4 mm) for this video. Embedding them to the full diameter of the axle goes some way to ensuring that the won’t pop out during string fitting.

Bridge Saddle Dimensions

  • Bridge saddles length: 5/8″
  • Bridge saddles width: Top & bottom E: 1/2″ (12.7 mm), middle four: 13/32″ (10.3 mm)
  • Bridge saddles height: Low and high E: 35/128″ (6.95 mm) A & B: 39/128″ (7.74 mm) D & G: 43/128″ (8.53 mm)
  • Roller rebate width: 25/128″ (4.96 mm)
  • Roller rebate depth: 3/32″ (2.4 mm) on all saddles
  • Screw holes to accept a cheese head machine screw (M3 or 6BA), 2 mm head depth

Bridge Rollers Specification

  • Overall width including axles: 23/64″ (9.13 mm)
  • Cylinder width: 3/16″, 4.76 mm
  • Cylinder diameter: 11 SWG (2.946 mm). All cylinders have a 0.042″ (1.07 mm) toroidal channel
  • Axle length: 23/64″ (9.13 mm)
  • Axle diameter: 1/32″ (0.8 mm)

The following information is essential when attemping aluminium milling on a CNC router (as opposed to a liquid cooled CNC milling machine):

  • High Brinell hardness alloys machine better, e.g. 6061-T6. Temper (T-number) is important
  • Use a very low XY feed rate, e.g. 500 mm/min
  • Use a small diameter, SINGLE FLUTE cutter
  • Shave the metal (e.g. 0.05 mm depth per pass)
  • Decrement the cutter height off the stock because end mill flutes are not designed for drilling
  • Use a spindle speed less than 10,000 rpm (e.g. 7,500 rpm)
  • Use a lubricant, e.g. WD-40 Specialist dry PTFE

Brian May Red Special Guitar Neck Full CNC Cut Video

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I recently revised my Brian May Red Special guitar neck design to correct some original sin errors and incorporate a significant number of improvements (‘kaizen’), most notably to the thickness of the mahogany in the main section and the headstock. I also reinterpreted the region where the headstock lozenge shape meets the elliptical profile of the main section to improve the fidelity. Having improved my TurboCAD techniques in the five years or so since I began this project, I also took the opportunity to simplify the methods I use to design each part of the neck (tenon, main section and headstock) to achieve a better result.

I sourced more mahogany timber (from Manuel Angelini in France), prepared it using my Makita table saw and CNC cut the neck over several sessions in August 2021, over four years since I made my original neck. I recorded highlights of each session in full HD, 60 fps, speeded up the sequences and mixed them into a 13 minute long YouTube video illustrating each stage of the process. This is embedded below; further details are available in the YouTube description with time indexed titles.

I took every opportunity to improve the cutting and drilling processes including CNC cutting two large 2 degree and 4 degree wedges for drilling machine heads holes in the headstock and fixing screw and bolt holes in the tenon. I also made an extended bed for my mini drill press from 19 mm plywood to accommodate them. To maintain precise axial alignment for both the upper and lower side toolpaths, I fitted a “L”-shaped alignment bracket water-jet custom cut from 20 mm thick aluminium to the T-slot machine table. Credit to Jon Underhill for providing this. This was the first cut in which I deployed direct dust extraction by means of a Delta dust shoe and Dyson DC39 Animal vacuum cleaner.

To make subsequent assembly easier, I CNC cut a slot for the brass plate which the truss rod tensioner bolt butts up against and corrected the position of the rebate which accommodates it. I also drilled six dowel locating holes to mount a perspex template which I will use to align the fretboard precisely to the the mahogany.