Thanks for the explanation and I now understand the type of tachometer you added. Like you, I started with an import lathe (mine is a 7" swing lathe I bought in 1993 from a Taiwan importer) and over time added more features, realigned the headstock and tailstock, improved the motor controller, added Hall Effect tachometer bought on eBay, ER25 collet chuck, DRO, etc. and it just keeps going and pretty accurate for what I need.