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A project log for Fancy lathe made from garbage

A wood lathe with closed loop speed control made from garbage

shlonkinshlonkin 04/19/2015 at 10:360 Comments

I told you I had never worked with AC motors. Cut me some slack.

I built the circuitry and tested it out. The controller doesn't use regular PWM. Rather it switches on full 60Hz cycles. Thanks to the MOC3063 drivers this switching occurs at zero crossings. For example a half power setting would switch on every other cycle.

Things seemed to work ok. Sort of. But I noticed that at low power the motor was not so smooth and something just seemed wrong, so I did a little more research. I guess the motor was designed to spin at one particular speed and the right way to control the speed is by changing the AC frequency. It's not an impossible challenge, but I'm currently lacking the free time and motivation to delve into it. I also considered just building the thing with a one speed motor, but that kind of defeats the mission statement of the project.

Plus, the more I learn about wood lathes the more tempted I am to actually buy a proper one and try my hand at wood turning. Of course I would like to try my hand a few times before investing the large sum of money, so I'm keeping my eyes open for such an opportunity.

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