Brian May Red Special Roller Bridge CNC Milling by dsgb

Brian May Red Special Roller Bridge CNC Milling
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 this video I illustrate the process of making this intricate item by CNC milling. 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 was originally Brian's guitar solo from Queen: A Night at The Odeon then I replaced with the royalty free track "Beach Walk" from the RUclips audio library.
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 Saddles 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 to have a 0.042" (1.07 mm) toroidal channel
- Axle length: 23/64" (9.13 mm)
- Axle diameter: 1/32" (0.8 mm)
The penultimate splash screen at the end of the video gives some essential information for aluminium milling on a CNC router (as opposed to a liquid cooled CNC milling machine). This is repeated below:
- 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
00:01 - Measuring the prepared aluminium bar with digital vernier calipers
00:29 - Thicknessing the 10 mm aluminium bar to 9.0 mm
00:42 - Thicknessing the individual block sections to 7.0 mm, 7.8 mm and 8.6 mm
01:08 - Milling the 3/32" (2.4 mm) roller rebates in each block section
01:30 - Milling the cheese head screw countersink
02:14 - Drilling the cheese head machine screw shaft bore with a 3 mm diameter solid carbide jobber drill
02:50 - Milling the outline and roundovers
04:10 - Cutting out the six individual roller saddle blocks
05:38 - Milling the roller axle channels (half height, i.e. 0.4 mm)
06:27 - Test fitting stainless steel rollers
06:35 - Outro with aluminium milling essential information screen
For further information on my Brian May Red Special guitar replica build project and other Brian May related guitars and equipment projects, please visit my website:
dsgb.net
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