Home-made CNC mill

BorisBoris Posts: 81
edited 2005-02-06 - 19:56:31 in General Discussion
I have had the idea for building my own home-made CNC mill for a while now. Now that I have a bit more free time, I started doing some preliminary research.
Here is my question:
What are the pros and cons for using a continuos rotation servo motor vs a stepper motor?

Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-01-11 - 22:57:56
    A·stepper motor is a better fit for this application. By using a stepper motor you inherently know the angle of rotation (just count the pulses you feed the motor)·and hence the linear travel of the bed. A continuous servo does not provide this information, you would need some form of shaft encoder to detect your rotation.

    Paul
  • Jim McCorisonJim McCorison Posts: 359
    edited 2005-01-12 - 01:38:39
    Boris,

    You might also want to check out the thread http://forums.parallax.com/showthread.php?p=521858 over in the Basic Stamp forum. There is a side discussion which relates to your project that might be helpful.

    Jim
  • bobledouxbobledoux Posts: 187
    edited 2005-01-12 - 13:50:04
    Try www.crankorgan.com. He has his own message board that deals with these issues, among many others, in detail.
  • Gary M. ReeseGary M. Reese Posts: 5
    edited 2005-01-15 - 18:00:47
    Also search the web for <hobby plotter> or router . I think you'll find as I did it's the software that will be a problem.
    I have the newest MS visual basic and C++ enviornments. No body will help with a basic program example to get you started.
    One that will open up in the MS programing environment. The problem is with MS OS security on the ports. The forum The Code Project came as close as any.
  • pjvpjv Posts: 1,903
    edited 2005-01-15 - 19:36:48
    Hello Boris;

    A lot depends on how powerful a machine you are wanting to build. If all you need is a "small" X Y positioner where the X and Y speeds need not track each other, as in precise diagonal or sloping lines, then stepping motors are BY FAR the easiest to implement. I have built several of these simple positioners where X and Y move simultaneously, but independently, as in not "tracked".

    If you are pulling along a heavy load and need more motive power, or greater traverse speed, then steppers become more limiting and difficult to drive reliably without missing steps.

    The only way to make a "real" CNC machine (I have a commercial 10 horsepower one of these as well) that can move some hundreds of pound loads and trace curves is with servo motors. The software for this is a VERY difficult task, and you are likely not to fare very well along this path.


    In basic summary: unless your application is for something very light (a pound or two) and the X Y can move "untracked", forget making your own.

    That said, experimenting is always fun, and you can learn a bunch too. Just don't expect too much; thats why the commercial stuff costs what it does.

    Have fun,

    Peter
  • randyazrandyaz Posts: 61
    edited 2005-02-06 - 19:56:31
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