The Bool Audio Blog

May 2023 — The machine learns a new trick 

With the CNC mill up and running, we hit an early problem. Several tonearm components require turned parts — cylindrical work that a mill alone can't produce. The options were to buy a separate CNC lathe, send the work out, or find another way. 

We found another way. By loading stock material into the machine's spindle and mounting turning tools on the bed, the CNC mill can be made to function as a lathe. It sounds unconventional, and it is — but with some careful programming through Fusion 360 and a few custom sub-routines in the CNC control, it works extremely well. One machine, two functions, no compromise on the parts. 

With that sorted, focus shifted to the tonearm in earnest. The third revision of the prototype was well underway, with the lathe function proving particularly useful for the more complex turned components. First production was feeling close.

Alongside the tonearm work, we also started a small production run of something else — the channel indicators for the tonearm cable's RCA plugs, machined from acetal thermoplastic. Small parts, but satisfying to see coming off the machine in quantity. 

We also made the decision around this time to introduce a transparent record clamp — a simple, elegant product that physically couples the record to the platter using a preload washer, with the added benefit of flattening mildly warped records. It's the kind of thing that makes an immediate, audible difference and is easy to explain to someone who's never tried one. 

The arm rest parts for the third prototype revision were also completed this month, combining both the lathe and milling functions of the machine — a good test of how well the two modes work together in practice.