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Which motor is the right motor?

Discussion in 'Sensors and Actuators' started by MuntyScruntfundle, Nov 6, 2017.

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  1. MuntyScruntfundle

    MuntyScruntfundle

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    Nov 6, 2017
    I'm staring to realise this is a rather difficult question to answer.

    I'm an engineer, machinist, I work with wood and metal, I've worked running a software design business for years, and I'm not retired. I've never done anything with electronics. So I thought I was time.

    I wan't to build a small router/cnc machine. I don't want to buy one, I don't want to buy a kit, I want to research, buy all the bits I need separately and learn along the way. I'm sure I'll order loads of stuff incorrectly and have a big box of left overs, but I'll find a way to use them later.

    So, which motor! The motors are really the heart of the project, if they're not going to be up to the job it's not worth starting! I need them to be powerful, it basically going to be a milling machine so it needs torque, but I'd sooner not go up to 24v. I'm working on a small Raspberry project at the moment and beginning to understand the understand the different wiring options, but everything will go through a controller which I'll purchase, I'm not making those.

    What would people suggest?
     
  2. Minder

    Minder

    2,966
    626
    Apr 24, 2015
    What type of milling do you want to do? Do you need high RPM?
    For positioning, you could go to steppers for economy.
    Gecko make a good product.
    What is high about 24v? That is considered the very low end for a spindle voltage.
    For cheap software there is the PC based Mach3/4
    M.
     
  3. kellys_eye

    kellys_eye

    4,276
    1,146
    Jun 25, 2010
    Invariably you're looking at stepper motors which themselves come in NEMA standard i.e. 17, 23, 34 etc where the number indicates the size (in inches) across the body.

    The motors are also rated by torque, coil voltage/current, steps/rev etc etc. Most stepper motors are deliberately run over their stated voltage to provide good torque and speed response so 24V will be a minimum rather than a maximum for most systems.

    Most common CNC systems use 200 steps per rev NEMA motors to give accuracy and repeatability but the actual choice will depend on the material you plan to machine and the speeds at which you want to do it.

    There are forums dedicated to CNC machine making that would offer advice from beginner to expert if you are serious about your plans.
     
  4. MuntyScruntfundle

    MuntyScruntfundle

    3
    0
    Nov 6, 2017
    I guess 24v would be low for motors that can't be allowed to stall, that makes sense. Ok, well, I'm prepared to go up, it's just 12 seemed like a good starting place.

    I had envisaged the positioning motors would be steppers, being able to replicate a position is paramount. As for the spindle, as variable as possible I suppose.

    I might be looking at low grade Ali, but mostly plastics, Nylon and certain poly's.

    I'll look around for cnc forums, I didn't think of that as an avenue,

    Thanks folks.
     
  5. kellys_eye

    kellys_eye

    4,276
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    Jun 25, 2010
    The key to successful CNC-ing is rigidity.

    If you build a CNC machine WITHOUT rigidity you will live to regret it and end up repeating the process until you get it right.

    Best to start as you mean to go on and use the 'solid' parts - buy cheap, buy twice.
     
  6. Minder

    Minder

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    626
    Apr 24, 2015
    One of the largest forums for information, especially DIY is the CNCzone.
    I was in the CNC retrofit business for several years and know it pays to buy quality parts off the bat,
    For example, most start out by buying SMPS power Supplies for servo/steppers when not only is a regulated supply not needed, and although often cheaper than the linear type, they have a high failure rate, where the linear is much more reliable and much easier to repair, if needed.
    M.
     
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