Making records at home - my disc recorder project

UPDATE - 21 March 2022 - please see below
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The latest, after a five-year gap, of my efforts to build a working record lathe for home use. This video tries to explain a bit about what such a machine is and how mine works, and ends with a demonstration of results achieved, interleaving the original mono mix of the source file with playback from the record made from it. You can jump straight to the playback demo at 8:48.
Sources and acknowledgements:
Disc recorder block diagram - Donald Aldous, "Manual of direct disc recording", Bernards 1943
Cutterhead diagram - Larry Boden, "Basic disc mastering", 2nd ed. 2012
Pressing process diagram - welcometo1979.com/
Stepper motor drivers - learn.watterot...
V-Slot aluminium extrusions - ooznest.co.uk/
Linear rail unit - tech.thk.com/
Z-axis slide - www.optosigma....
FreeCad - www.freecadweb...
3D printing service - i.materialise....
Coin exciters - www.tectonicau...
Sapphire embossing stylus - www.recordlath...
Audacity audio software - www.audacityte...
Music for demodisc - Jason Shaw, audionautix.com/
The very wonderful Lathe Trolls site - www.lathetroll...
UPDATE: 21 March 2022
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I've put together a first cut version of some instructions on how to build the lathe described in this video. Be aware that these instructions have been compiled some time after the event and are based on my memories of what I did at the time; so please forgive any omissions or inaccuracies.
The instructions relate to the lathe frame, transport and cutter head only. You will need to supply your own turntable deck, amplifier, any signal processing gear etc.
I've also uploaded my original FreeCad files for the dozen or so 3D-printable parts. These have the extension .FCStd, and you will need the FreeCad software to load these and export them to your printable file format of choice, e.g. .STL.
The system I built uses a stepper motor to move the cutter head transport, and this motor is controlled by an Arduino, which is itself harnessed by software ('Vinyl Burn') running on a PC. Vinyl Burn - developed in C# using Visual Studio - enables the user to plan out a record side, listing sound files (.WAV only) to be used, and setting characteristics of the record such as groove pitches, inter-track gaps, run-ins and -outs, playing speed and so on. When the user starts the cutting process, Vinyl Burn plays each of the sound files in turn through the PC's sound card, while sending signals via USB to the Arduino to control the cutter head motor speed.
'Vinyl Burn' and the associated Arduino sketch are more than likely to need some rewriting to reflect your own system's hardware, logic etc. Specifically, the Arduino software, as it stands, caters for a 20 x 4 LCD readout (interfaced via a 74HC595 register), two photo-interrupter limit switch circuits, the stepper motor driver itself (TMC 2208) and an optional thermistor circuit. I've included these two sets of software really as a possible starting point for your own project.
All software released under GPL 3.0, instructions document under Creative Commons 4.0. All are offered 'as-is' and absolutely no warranty is given.
Instructions, FreeCad files and Arduino sketch: github.com/dn7...
Vinyl Burn: github.com/dn7...
Good luck!