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CNC board using microcontroller

Discussion in 'Robotics & Mechatronics' started by Varunme, Mar 10, 2013.

  1. Varunme

    Varunme Member

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    i want to make a cnc controller with a uC,
    For that i want to know , how the pic sends the signal from parallel port with a cnc controller software,
    is it like one "on" and "off" for a single step, will the parallel port pin goes to "off" state after a step ?
     
  2. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Your question, while seemingly simple, does not provide enough information to allow a simple answer.

    For starters, the one pic output you describe would, ordinarily, be controlled by some manner of code. That code would dictate the output, i.e., starting condition (0 or 1), frequency, duration, etc. That in turn would be sent to a PWM circuit to control a servo on, say, a machining bed, and so on.

    I may be stating the obvious, but CNC controllers are enormously complex devices, especially if taken from CAD file design all the way to finished product.

    Please elaborate on your idea.
     
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  3. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    I agree... The description from your post, leads us to believe that this is a non starter... I am not disrespecting you but if you don't know the basic's, we'll all struggle.

    Even I won't attempt a CNC... I have had an engraving machine upstairs for over 4 years...... I wrote a program to move all the steppers but reading a gerber or an orcad output requires a bit more patience that i care to bother with...
     
  4. dave

    Dave New Member

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  5. Varunme

    Varunme Member

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    ok so , the duration of the state also determines the steps?,
    so for example if the onstate stays for 1ms then 1step, 2ms for 2steps etc ?

    (I am just asking about the processing of data sent by some software, eg: mach3 through Parallel port. and convert into stepper pulse)
    The frequency is for microstepping ?


    or should i go for dedicated stepper pulse generator chips from toshiba etc ?
     
    Last edited: Mar 10, 2013
  6. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    Its a lot easier to program.. especially if you have 3 axis...
     
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  7. RichTheDude

    RichTheDude Active Member

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    I am not too sure I get what you are you trying to ask but if your contemplating making the electronics (based on a PIC) I would not bother.

    I have just brought a 3 axis control board that works a treat with Mach3 or linuxCNC. I have yet to convert my mill, as I am waiting for the brackets to mount the steppers.

    A TB6560 3 axis parallel control board can be had on ebay for < £30, and you can get the board + steppers (nema23) and PSU for around £120. I may convert my mill to a 4 axis one sometime (motorised dividing head), but I will do that when and if I have the cash and reason to do so :p
     
  8. bryan1

    bryan1 Well-Known Member

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    Yea as Rich said one can get a 3 axis microstepping board off fleabay pretty cheap and I got one for $34 delivered

    3 axis controller.jpg

    Thats the one I got and I found my old 1.6gig puter basically hung on trying to compile a image to Gcode file in Kcam. I'm going to give Mach3 a go and if that does the same then EMC2 will be my best bet. To get an idea of the speed a uC would be rquired to process a Gcode file just go look at the user manual for Mach3.

    Regards Bryan
     
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