Before I begin the design phase of a project, I plan out the modifications and then acquire the hardware. This might seem like an illogical approach but there are several reasons why I do it this way. Firstly, hardware can increase in price, go in and out of stock or cease being produced entirely in the timescales that it takes to plan and execute my projects. Therefore I prefer to acquire everything I need and have it sitting in a drawer for many months or years rather than regret not buying something down the line when it is twice the price, or no longer available.
Secondly, as I have stated in my other project articles, I prefer to design around the physical objects I have in my possession rather than rely on manufacturer’s specification sheets or assumptions based on previous work, informal advice on internet sites, etc. I measure the objects with digital calipers and build in necessary additional tolerances at the design stage. This avoids or reduces the risk of re-work post assembly when it could adversely affect the physical status or cosmetic appearance of the instrument.
For this project, the hardware (tremolo arm and tailpiece, conversion style fulcrum plate, bolts and spring cups, roller bridge and custom aluminium control knobs) came from César Beltran in Lima, Peru and the set of Burns Mini Tri-Sonic pickups from Barry Gibson at Burns London. These units are designed as drop-in replacements for Stratocaster single coil pickups and are also fitted to the Burns Cobra guitar as standard. They are still available at the time of writing for a reasonable £135. See the accessories section of the Burns London website:
“For many years guitar players have expressed the need to obtain the classic Tri-Sonic sound from their traditional style double-cut guitars, without the necessity of having to carve larger cavities in the instrument bodies or alter the pick guards/scratch plates to accommodate the larger original units.
By carefully engineering and condensing the original internals and easing them inside a narrower Tri-Sonic casing, guitarists can now enjoy the thick, ringing mids and smooth sustain of the classic 60s Tri-Sonic, whilst still having access to traditional single coil sounds and warm humbucking tones – all in one instrument!”
César was extremely accommodating and not only designed me a scaled down version of the original tremolo arm which Brian made from a bicycle saddle bag holder but also a delightful 3/4 scale set of aluminium control knobs. César has been selling Red Special hardware (eBay user ID: otramalditanoche) for some years now and Nigel Knight turned to him for custom hardware when he was doing his first Burns conversion project. As you can see in the image below I had to modify the tremolo tailpiece to get it to fit in the restricted width available in this tremolo cavity.
I had to do some calculations based on using a set of 0.011 to 0.050 gauge strings and the 19″ scale length assuming an open F tuning to estimate the spring characteristics needed to balance the string tension and give a reasonably authentic feel to the tremolo. I then ordered a set of LC 072H 03 M springs from Lee Spring in the U.K. They had the following characteristics:
Outside Diameter: 15.239 mm
Hole Diameter: 15.875 mm
Wire Diameter: 1.828 mm
Load at Solid Length: 133.440 N
Free Length: 25.400 mm
Rate: 9.63 N/mm
Solid Length: 12.852 mm
Rod Diameter: 11.099 mm
Number of Coils: 4.9
Total Coils: 6.9
Material: Music wire
Finish: Zinc plate and bake as per ASTM B633
Part 3: Body and Neck Design
Part 1: Introduction