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Re: [SherlineCNC] New to CNC - Howto CNC

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    Here I my comments with 9 years experienec. The PC is the least important part ! The most important part is the sw, either a closed box (usb controllers, any
    Message 1 of 30 , Feb 1, 2013
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      Here I my comments with 9 years experienec.

      The PC is the least important part !

      The most important part is the sw, either a closed box
      (usb controllers, any nr of hw controllers)- dont pick any of these
      mach3-easy and cheap
      emc2-far less easy but no buying cost

      The cost of mach3 will be moot, as you will spend far more on everything

      The nr1 error is typically trying to do it "cheap".
      This leads to 2 results.
      1. You abandon it as "not working"
      2. You then spend a lot more, to get a working solution

      Ie, most of this stuff has a cost for a reason.
      There is huge competition in the field, and the sweet spot is where you
      really want to be.

      Dont buy anything expect bipolar microstepping drivers (if using steppers).
      Chinese 50V/4a microstepping drivers are fine, and cost about the same
      as geckos.
      So are small geckos (g251s). Totally equivalent in use.
      Dont buy old or small steppers !
      A good stepper today has 3-5 Nm of torque for about the same cost as a
      little, weak, 120 ozin one.
      Use about 48V DC with you choice of driver electronics.
      ONLY consider bipolar parallel wired square-body steppers.

      Dont buy poor mounts, poor couplers, wrong belts (like xl series).
      Dont use poor cabling ! Use cabling meant to flex.

      To connect the steppers you need either couplers or belts.
      Cheap couplers are not very accurate - and good couplers are expensive.
      This will not matter if you buy poor belts, poor (cheap) mounts, small
      motors, or unshielded cables as the errors will be masked by the other
      A good cheap choice is HTD belts and pulleys, 5 mm profile (size) and 15
      mm wide.
      You can use the lathe to bore the pulleys to size for the steppers, or
      get it already done.

      You will need cam sw, and cad sw, and the machine controller, either
      mach3 or emc2.
      Learning everything in linux is a big undertaking, if you are not
      familiar with this.
      So it is in windows, but learning an opsys at the same time is a whole
      new set up problems.

      You will spend about 200-300$/axis with steppers.
      You CANNOT do a good job for much less.

      Approx ballpark costs.
      50$ stepper 2.5-4 Nm
      80$ Microstepping bipolar driver for stepper motor, 48V, 3-4 amps
      10$ pulley, 12-16 tooth (stepper end)
      20$ pulley, screw end, 16-48 teeth
      10$ limit switches
      10$ cabling
      180 $ per axis, add 20$ shipping and handling, about 200$/axis

      50$ Cabling 10+ m
      50$ connectors
      40$ main switch, estop
      100 $ breakout board, also called bob
      50$ box
      100$ PSU
      Remember to add some cable glands, strain reliefs, drills, mains cord,
      connector etc etc.
      All this stuff adds up.
      So the costs run about 1200 $ for a 3 axis setup.

      IF you use a weak, slow, less precise stepper, you will get about 30% of
      the performance, and save about 25$/axis.
      Absolutely not worth it.
      So forget integrated chinese tb6xxx drives with bob and 3 axis drivers.
      They work ( I have 2), but are relatively about 50% of the speed of the
      good microstepping drivers (or geckos), and again, you save 25$ /axis
      for 30% of total performance.

      You can start with mach3 as a demo (free).
      Once you learn, you can add mach3 licsense, 150$, mach3 wizards,50$
      iirc, basic cam (250$ meshcam etc and so on).

      Most of Jeff Birts (Soigeneris) kit is good, and he is a reputable long
      time seller.
      Any nr of suppliers in the US also sell good hw and accessories (over 30).

      > Hello!
      > My son and I are at the first step in turning a manual sherline lathe
      > with milling column
      > Into a CNC mill. I realize tha with a fat checkbook someone can order
      > sherlines complete
      > Turnkey CNC mill.....but from all the products out there I see, it's
      > clear that its possible
      > To make the upgrade much cheaper. That's the nature of my first
      > question....
      > One Good thing is, my son is Very computer literate, so our first step
      > is to define the
      > Basic hardware needs........what I know so far is that you need:
      > 1. The sherline mill
      > 2. The stepper motors
      > 3 . That box interface between the computer and the stepper motors
      > 4. The computer and a CNC program
      > Is there a basic Dummy's type of book out there that sorts out how
      > someone can put together
      > A machine which addresses how to not overspend by getting more
      > capabilities than you
      > Will need?
      > And along with that how spend the least $ to do the job, by mixing and
      > matching the best
      > Stepper motor suppliers with interface ( called drivers?) manufacturers?
      > Well Thankyou for your help sorting out what appears to be a minefield
      > of complicated
      > Choices. Dave

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