In preparation, I did some calculations to see if it would be possible to achieve standard EADGBE tuning using medium gauge strings (0.011 to 0.050″). I had to select open F tuning (i.e. raised one semitone) on the 3/4 scale Brian May Red Special project because this had a floating tremolo, therefore strings with low tension (under 10 lbs) would have an adverse affect on the overall tuning given that I was trying to achieve a similar overall string tension to Brian May’s original Red Special (79-80 lbs). As you can see from the table below, it is possible to fit medium gauge strings to a guitar with an 18.5″ scale, tune it to open E and achieve reasonable individual string tensions.
With the calculations done, I ordered a set of Optima Chrome 4028M strings for evaluation during the mechanical set-up and a set of Optima Gold 2028M strings for the final stringing up from AStrings. I fitted the bridge and humbucker pickup, strung up the guitar, set the playing action to 1.6 mm (1/16″) at the 17th fret, set the intonation corrections and finally measured the distance from the pickup casing to the strings in order to calculate how thick the spacers under the pickup mounting tabs would need to be. With distances of 11.5 mm to the high E fretted string and 12.0 mm to the low E fretted string and a recommended pickup-to-string spacing of 2.4 mm (3/32″), the answer was around 3/8″ give or take 0.5 mm. As usual, I then made two custom thicknessed spacers from plastic rod and drilled screw holes through the centre.
Not surprisingly, I discovered that the gear mechanism of some tuners slipped and would not hold a steady tuning. Presumably this is because they are designed for lower torque applications such as budget acoustic guitars with nylon strings. Therefore, prior to final tuning, I removed the screw holding the gear cog onto each tuner shaft and applied some threadlock adhesive to prevent slippage.