Sewing machine Servo?

[Max Power]

Hello all,

I'm still on a quest to put a variable speed motor on the spindle of my Taig lathe. Simple enough except ideally I would want to control spindle speed through software like Mach so I could use it to thread on the lathe.

I floated an idea about using a stepper as a spindle but due to high RPM torque loss and other concerns about cut quality I have discounted as an option...

I have found a cheap sewing machine motor in the right RPM range. It is advertised as a DC servo motor. There must be some sort of feedback loop to control the speed so this might be true. The speed itself is controlled by a small knob on the end of the motor along with a spindle direction switch so control is all internal.

I'm hoping that someone here with more knowledge than I can help appraise this idea. Would it be possible to take something like this, rip the stock controls off and hook up some sort of driver to control the speed/direction by software? Has anyone attempted this? Any advise you have is welcome.

The motor I'm considering is a Yamata FESM-400. It would be like using a treadmill motor as some people have for spindle drive but is small enough for my needs, as I don't require 2+hp on a Taig.

Thanks in advance for any advice,

MP

[txcowdog]

I have a lot of industrial sewing machines and saw the servo motors so I tried one. Very noisy and after about one hour of use the motor got hot and lost about 60% of it's RPM. I took off the servo and put the old drive motor back on. For me the experiment was a total failure.

[NC Cams]

Try this:

Obtain a motor from a heater blower from a car. It runs on 12-15 vdc and they are definitely speed adjustable.

Craft up a PWM'd speed control using either a motor control IC or even a mosfet in concert with an LM324 based PWM circuit.

PWM circuit: create a triangular wave generator. Feed that into one side of an op amp and then a voltage from a simple potentiometer into the other - have the fet drive an op amp. The PWM will give you plenty of torque and also infinite speed adjustability. Set the square wave freq to about 3-5 khz

Why a car blower motor? Real powerful and real cheap and mucho RPM. If that works, you can use the results to find a more "professional" motor but for DIY use, you'd be amazed at what a heater blower motor will do.

You may even be lucky and score a Denso motor - some of these have ball bearings in them - the GM Ford and DCX ones had oilite bushings but that doesn't rule them out for experimentation purposed.

[Max Power]

Hey guys,

Thanks very much for the help!

Txcowdog: I appreciate the first hand experience. That was exactly what I wanted to know. I suppose it makes sense, after all sewing machines are not really meant for constant use. I will scrap that idea. I think a treadmill motor would be better suited to spindle driving now ( if I go that way). Cheers.

NC Cams: I don't know what to say. That is a great idea. I've got to get a better understanding of electronics and your plan will accomplish that for sure. Once I decypher your instructions I'm off to the races! I will try building it and let you know how it goes. A blower motor might just give me enough power to do the job as well. Great suggestion. Thanks for taking the time to lay it out for me.