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Re: 8541 package questions

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  • jowhowho
    I have Sherline CNC lathes, mills, rotary tables, and stepper heads. I like Sherline. I do not like the Sherline/Mumford stepper driver. If you want to know
    Message 1 of 35 , Jun 28, 2013
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      I have Sherline CNC lathes, mills, rotary tables, and stepper heads. I like Sherline. I do not like the Sherline/Mumford stepper driver.

      If you want to know about steppers and stepper drivers, look around on the web for anything that "Mariss Freimanis" says. He is the Guru behind Geckodrive. He knows his motors.

      I use my setup to make parts for restoring old scientific and mathematical instruments. Threads, knurls, gears, whatever is needed. Most of what I cut is leaded brass and leaded steel. I use very little CAD, and very little CAM. I hand code my G-code, and usually use the loops, conditionals, and subroutines that the LinuxCNC parser reads. Sometimes I even do some numerical methods in-line.

      --- In SherlineCNC@yahoogroups.com, Gabe Pena <gp_illustrator@...> wrote:
      > Thanks Justin. The main reason that I'm going with the package is for simplicities sake. I work full time during the day and do freelance illustration after work, and with a wife and kids, free time is a precious commodity I don't have. Now it might seem like I'm rushing, but I've been researching, reading and asking questions about this stuff for about 4 years now, and without putting theory into practice, I'm not going to get anywhere. All the technical info and terminology starts becoming a blurred mess when it's just read and not really physically applied. I learn better by doing.
      >    I do recall people in this group doing detailed cutting with the sherline, which is what I want, detailed cuts/molds out of aluminum. No more than 1/2 an inch depth at the most. But if Geckos are better (which is what I've heard a lot of) I'd rather get those, but in all reality, how much is saved by buying in parts versus the complete kit which saves time? I'm all for saving money cause I know the cutting tools might be pricey, plus I'm not rich :).
      >    What do you use your set up for? Do you have pics you'd like to share?
      > I appreciate all the advise given.
      > Gabe
    • Gabe Pena
      Thanks Jeff. So would I better off then with the smaller motor. The endgame here for me is to cut molds for highly detailed organic pieces that will be plastic
      Message 35 of 35 , Jul 1, 2013
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        Thanks Jeff. So would I better off then with the smaller motor. The endgame here for me is to cut molds for highly detailed organic pieces that will be plastic injected. Much like what you see in 32mm wargamming pieces.


        From: Jeffrey Birt <birt_j@...>
        To: SherlineCNC@yahoogroups.com
        Sent: Monday, July 1, 2013 3:32 PM
        Subject: RE: [SherlineCNC] Re: 8541 package questions - PMDX-340

        With the 20TPI screws on the Sherline larger motor are a detriment. You
        already have a large amount of torque developed due to the mechanical
        reduction. What you want are motors with low inductance and low inertia (low
        rotating mass). We package 166 oz-in motor with our Taig and Sherline kits.
        If you search for Soigeneris on YouTube you'll find some videos of a Taig
        doing 250 IPM with my 'tiny' motors.

        Matching the motor/driver/power supply is the key to getting the most out of
        the motors and your machine. Bigger is not better.

        Jeff Birt


        From: SherlineCNC@yahoogroups.com [mailto:SherlineCNC@yahoogroups.com] On
        Behalf Of bruce_e_layne
        Sent: Monday, July 01, 2013 5:17 PM
        To: SherlineCNC@yahoogroups.com
        Subject: [SherlineCNC] Re: 8541 package questions - PMDX-340

        --- In SherlineCNC@yahoogroups.com <mailto:SherlineCNC%40yahoogroups.com> ,
        Hamilton Elliott <hamilton@...> wrote:
        > Keling steppers KL23H284-35-4B which are too big
        > and I believe makes them slower and more likely to do damage if
        > accidents happen... Bigger is not always better!

        I'd generally agree that bigger and more powerful isn't always better, much
        as that contradicts the basic programming of my Y chromosome.

        I put larger motors on my 25" X 49" CNC router because the specified NEMA 23
        motors seemed a bit anemic. I haven't installed the end limit switches yet,
        so I set the maximum current in the stepper motor controllers to a lower
        value, and they still have plenty of torque at low speeds. If your only
        concern with larger motors is too much torque, you should be able to reduce
        the torque by reducing the current, which is done with DIP switch or rotary
        switch settings or possibly potentiometers on modern stepper drivers.

        The 5mm/turn ball screws on my CNC router provide a lot of mechanical
        advantage. A crash in X or Y would be ugly, but I was genuinely concerned
        that a +Z crash would damage the top of the Z stage. I doubt it'd break the
        1/4-20 machine screws, even in shear, but the top plate was deforming upward
        at an unhealthy angle and the tapped holes in the aluminum plates were
        probably elongating.

        I went a bit larger on the NEMA 23 stepper motors on my Sherline 4000 CNC
        ready lathe than Sherline specified, but I didn't go crazy. I didn't want a
        big heavy stepper motor cantilevered out on the end of the cross slide where
        it might contribute to accelerated wear in the saddle or rails.

        > If you think that you will want to use the mill by turning
        > the handles then you need to get the double ended shafts.
        > I put the handwheels on for a short time and then removed
        > them because of vibration and with the larger motors they
        > were too hard to turn comfortably.

        I used double shaft motors on my CNC router so I could turn the axes by hand
        when the stepper drives were powered down, but I used large diameter knobs
        rather than the more traditional handles. I didn't want the spinning handles
        protruding where they could catch on stray objects, and the knobs are
        radially symmetric so they don't tend to cause harmonic problems that can
        momentarily stall a stepper motor at certain speeds. Those lost steps can be
        very frustrating (ruined parts) and very difficult to diagnose.

        I decided against double shaft motors on my Sherline 4000 CNC mini lathe.
        For the times I'd use it as a manual lathe, I'll probably jog it via
        LinuxCNC or type G code into the MDI interface rather than cranking handles.
        Most of my manual lathe work will be done on a larger lathe. I also wanted
        the smallest and neatest integration for that CNC mini lathe and I didn't
        want knobs hanging out at the ends of the axes. I was going for the CNC look
        and feel, and not the CNC conversion look and feel, not that there's
        anything wrong with that.

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        [Non-text portions of this message have been removed]
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