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My CNC mill comes alive!

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  • Les Wilk
    Hi all, First, to Nick: Got all the mill parts and it s up and running. I tried a demo file on a chunk of lexan sheet, which worked nicely. I haven t yet done
    Message 1 of 2 , Jul 1, 2000
      Hi all,

      First, to Nick: Got all the mill parts and it's up and running. I
      tried a demo file on a chunk of lexan sheet, which worked nicely. I
      haven't yet done anything in metal (maybe today). The lathe also came
      with all its accessories, except the motor, which must've been packed
      separately.

      Now a couple of questions to anyone with the CNC mill (sorry for
      being long-winded):

      [NB: my system is a pentium 166 laptop, running supercam in DOS]

      1) Using the default speed settings, etc. from the "millset1" file as
      described in my little guide, when I use the stepxto, stepyto,
      stepzto commands and hold the mouse button down, on some axes, the
      steppers jam as they ramp up to slew speed. I fiddled for quite some
      time with the setxymaxss and similar commands and had to REALLY slow
      the rates down (eg. 500 steps/sec max) for everything to work
      reliably. Then I tried the stepx, stepy, stepz directives and they
      happen to work flawlessly with even the default config. Anyone know
      why the mouse commands would work so differently?

      2) Related to the above. While I was trying to get the mouse commands
      to work without jamming (before I noticed that the numerical offset
      commands worked better), I went ahead and opened the case of the
      controller. The first thing I saw was a big round 'dimmer switch'
      type knob with text near it saying 'power'. Being brave (and a bit
      risky), I held the mouse button down and started turing the knob. Lo
      and behold the stepper cleaned up its act and was going nicely. I
      have left the knob at the new setting which I assume is giving more
      torque. The setting also affects the traveling done by the computer
      (which was already working better than the mouse). Anyone know (a)
      what that knob does exactly, (b) is it safe to bump it up like I did?

      3) What does the "chopping frequency" do? This is a setting you pick
      in the portmode command. I have not changed it since I don't know
      what it does. How do you know what value to use, and are there times
      when you'd want to change it from the default that it picks (which
      changes depending on the step rate in use)?

      4) I haven't done anything special to the mill in terms of
      lubrication since it seemed to be running relatively smoothly
      already. To get the smoothest performance, should I be disassembling
      the thing to clean it up and such? What and how would you recommend
      lubricating/adjusting the parts?

      This is mighty neat machine, that's for sure. Though we'll be using
      it for some business prototyping and concept design, I think I'll be
      spending a few nights on work of my own too :)

      Regards,

      Kris Wilk
      ReefNet Inc.
      www.reefnet.on.ca
    • Tony Jeffree
      ... As Nick has said in his response, the mouse commands don t seem to work quite the same as the other moves. I spent a long time fiddling with my settings
      Message 2 of 2 , Jul 3, 2000
        At 17:13 01/07/00 +0000, you wrote:
        >Hi all,
        >
        >1) Using the default speed settings, etc. from the "millset1" file as
        >described in my little guide, when I use the stepxto, stepyto,
        >stepzto commands and hold the mouse button down, on some axes, the
        >steppers jam as they ramp up to slew speed. I fiddled for quite some
        >time with the setxymaxss and similar commands and had to REALLY slow
        >the rates down (eg. 500 steps/sec max) for everything to work
        >reliably. Then I tried the stepx, stepy, stepz directives and they
        >happen to work flawlessly with even the default config. Anyone know
        >why the mouse commands would work so differently?

        As Nick has said in his response, the mouse commands don't seem to work
        quite the same as the other moves. I spent a long time fiddling with my
        settings before I managed to find a worhable combination. I posted my
        current settings a while back in response to one of Nick's questions -
        should be in the message archive.


        >2) Related to the above. While I was trying to get the mouse commands
        >to work without jamming (before I noticed that the numerical offset
        >commands worked better), I went ahead and opened the case of the
        >controller. The first thing I saw was a big round 'dimmer switch'
        >type knob with text near it saying 'power'. Being brave (and a bit
        >risky), I held the mouse button down and started turing the knob. Lo
        >and behold the stepper cleaned up its act and was going nicely. I
        >have left the knob at the new setting which I assume is giving more
        >torque. The setting also affects the traveling done by the computer
        >(which was already working better than the mouse). Anyone know (a)
        >what that knob does exactly, (b) is it safe to bump it up like I did?

        Not played with this setting myself. I guess this is potentially the "tune
        for maximum smoke level" control, so should be used with care!


        >3) What does the "chopping frequency" do? This is a setting you pick
        >in the portmode command. I have not changed it since I don't know
        >what it does. How do you know what value to use, and are there times
        >when you'd want to change it from the default that it picks (which
        >changes depending on the step rate in use)?

        I've always left the chop mode switched off. The documentation doesn't say
        what this option does - I suspect that it allows you to set up an
        approximation to a chopper drive, where you overdrive the motors (use a
        power supply significantly higher than their normal voltage rating) in
        order to increase the current rise time in the motor windings, and you then
        "chop" the drive when the current in the phase winding reaches the motor's
        max current rating, switching the drive back on when the current drops
        again. With no feedback of the actual current levels in the motor
        windings, the best you could do would be to choose a switch on/off time
        that gets close to the desired current rating - but at best, this will only
        work properly for a particular motor speed.


        >4) I haven't done anything special to the mill in terms of
        >lubrication since it seemed to be running relatively smoothly
        >already. To get the smoothest performance, should I be disassembling
        >the thing to clean it up and such? What and how would you recommend
        >lubricating/adjusting the parts?

        As Nick says, lube the ways and the screws. A further point here - in
        standard form, the machine used to be sold without swarf protection for the
        Z and Y axis leadscrews (the X axis is covered bu the table, so is not a
        problem) - I don't know whether they have fixed this in later models. If
        you haven't already got them, fit swarf excluders for the Y and Z axes -
        easy to do with a bit of heavy duty polyethylene sheet or similar. I found
        that you can produce a usable "fanfold" from thick poly sheet by careful
        application of a domestic steam iron.

        Regards,
        Tony
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