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  1. #1
    Join Date
    Oct 2008
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    37

    Stepper Motor Size Rule of Thumb

    I've found this package of controller / motors / power supply.

    http://www.stepperworld.com/FET3dynamo.htm

    The larger motors are 190 oz in and I was wondering how do you gauge the size of motor you need for your application?

  2. #2
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    Gerry

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  3. #3
    Join Date
    Jun 2009
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    5
    That's a problem, it doesn't take into account mechanical efficiency of a machine.

  4. #4
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    Jun 2004
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    6618
    I would hate to try and read something that would have all the answers for every type machine a fella could dream up.
    There shouldn't be a problem with that. It is what it is. It will give you a starting point to see what type system you would want.
    THEN, you gotta take into consideration the efficiency of your ways and power train. Axis length, turns per inch, loaded weight of machine with parts and extra fixtures, rigidity, material being cut, etc......and the list can go on and on.

    I don't think all the answers are in any one place. Sometimes there are many many right answers. Building your own machine is more of a path that you take and not necessarily a recipe that you follow, though you can certainly do that. Then in those cases, most questions have been answered.
    Lee

  5. #5
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    Oct 2008
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    37
    So it looks like the package I found would work for a mid-sized CNC router. Say a 48" x 48" made with MDF. I suppose the best thing would be to get them, get a small application built, maybe 24" x 24" and see if it works. THen make a larger one and try the motors. If the motors don't work, I have my answer: Get bigger motors.

  6. #6
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    Jun 2003
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    3312
    You do realize that isn't a current controlled driver board?
    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com

  7. #7
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    Mar 2003
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    35538
    Quote Originally Posted by jallenmorris View Post
    So it looks like the package I found would work for a mid-sized CNC router.
    It'll work, but not very well. The Stepperworld is an inefficient drive, and is outperformed by most drives on the market today. You won't see many people using them here.

    Quote Originally Posted by jallenmorris View Post
    I suppose the best thing would be to get them, get a small application built, maybe 24" x 24" and see if it works. THen make a larger one and try the motors. If the motors don't work, I have my answer: Get bigger motors.
    Wrong answer. Bigger motors would probably be less likely to work. The motors and drive need to be matched together for best performance. Not all motors work well with all drives, although the better the drives, typically, the wider range of motors they're capable of running well.
    Gerry

    UCCNC 2017 Screenset
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    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  8. #8
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    Oct 2008
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    37
    I'm new to this and honestly have no idea what you mean.

    Quote Originally Posted by pminmo View Post
    You do realize that isn't a current controlled driver board?

  9. #9
    Join Date
    Feb 2004
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    1086
    Most drives (like the Gecko G540) use PWM, or Pulse Width Modulation, to effectively control current. This is basically pulsing the coil voltage on and off at a very high rate. Since the motor coils are inductive, they can't change voltage at this rate, so this effectively looks like a reduced current. Pretty slick.

    In contrast, the stepperworld controllers appear to use power resistors to control current at higher voltages. This is remarkably wasteful, and sends a lot of the power into heat, rather than into your motors. Agreed with Ger -- I would keep looking, Gecko makes a great product, although it may be out of your budget. Probotix isn't bad either, and is a lower current but also a lower priced solution than Gecko.

    Ahren
    www.cncrouterparts.com

  10. #10
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    Oct 2008
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    Thanks for the insight. I understood it the way you explain it. Energy has to go somewhere, and if you're sending more than necessary, it usually isn't good. That heat can build up over time and cause problems.

    My budget (provided a few clients pay me on time this week) will actually be about $1,000 to $1,500. I don't have a huge shop, (2 car garage turned into a wood shop), but should have room for a 48" x 48", maybe larger, but I don't think I need it for any of my projects.

    My only concern is finding good plans and being able to follow them.

    Quote Originally Posted by ahren View Post
    Most drives (like the Gecko G540) use PWM, or Pulse Width Modulation, to effectively control current. This is basically pulsing the coil voltage on and off at a very high rate. Since the motor coils are inductive, they can't change voltage at this rate, so this effectively looks like a reduced current. Pretty slick.

    In contrast, the stepperworld controllers appear to use power resistors to control current at higher voltages. This is remarkably wasteful, and sends a lot of the power into heat, rather than into your motors. Agreed with Ger -- I would keep looking, Gecko makes a great product, although it may be out of your budget. Probotix isn't bad either, and is a lower current but also a lower priced solution than Gecko.

    Ahren
    www.cncrouterparts.com

  11. #11
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    Feb 2004
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    1086
    You might check out the plans offered from myself and Nate at Fine Line Automation (www.finelineautomation.com) -- they're free, and can be downloaded from either website. If you want a larger machine than the current 2' x 3', Nate has modified the plans and kit he sells for people in the past -- you can see various permutations in the build logs on my site.

    Ahren
    www.cncrouterparts.com

  12. #12
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    Mar 2003
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    Also look at Joe's 4x4 hybrid plans. They're very popular, and apparent;y quite easy to build.
    www.joescnc.com
    Gerry

    UCCNC 2017 Screenset
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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  13. #13
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    Oct 2008
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    Am I correct in assuming that those Joe's CNC kits do NOT come with Steppers? If so, I think they're WAY too cheap. What size of steppers should be used with those? 390 oz in?

    Quote Originally Posted by ger21 View Post
    Also look at Joe's 4x4 hybrid plans. They're very popular, and apparent;y quite easy to build.
    www.joescnc.com

  14. #14
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    I think a 2' x 3' would be large enough for me to begin with. I'm planning on using it for my own enjoyment. Maybe do a few projects for friends. There are all kinds of little antique shops around my town, which is a small suburb of OKC. I thought taking in a few projects to display might help get the thing to help pay for itself.

    Anyone else had success doing this?

    Quote Originally Posted by ahren View Post
    You might check out the plans offered from myself and Nate at Fine Line Automation (www.finelineautomation.com) -- they're free, and can be downloaded from either website. If you want a larger machine than the current 2' x 3', Nate has modified the plans and kit he sells for people in the past -- you can see various permutations in the build logs on my site.

    Ahren
    www.cncrouterparts.com

  15. #15
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    Mar 2003
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    35538
    Joe's kits only come with the wood and plastic parts shown in the pics, and nothing more. You need to supply all the hardware and electronics. Expect to spend between $1000-$1500 for the 2006 model, and a bit more for the 4x4. Costs can vary widely, depending on components chosen.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  16. #16
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    Oct 2008
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    What is the size of the 2006? I went to the website but don't recall seeing exact dimensions of the cutting area.


    EDIT:

    Ok, just saw it's 24" x 48".

    I do like the 4' x 4' design better. I'm just not sure about all of the hardware as well. I've found a 2' x 3' with steppers and everything for $1,275. Doesn't seem to be a bad deal as long as the parts are quality.

    Quote Originally Posted by ger21 View Post
    Joe's kits only come with the wood and plastic parts shown in the pics, and nothing more. You need to supply all the hardware and electronics. Expect to spend between $1000-$1500 for the 2006 model, and a bit more for the 4x4. Costs can vary widely, depending on components chosen.

  17. #17
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    Feb 2004
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    1086
    Where did you find the $1275 2' x 3' kit? If you're talking about the FLA-100 from Fine Line Automation, that doesn't include the electronics, unfortunately. It's still a great deal at that price for an all-metal machine, but you will still need to get steppers, a driver, cables and a power supply. Nate is supposed to start selling that stuff soon (same parts as I am selling), although there are multiple other sources for them. I'd figure ~$500 for a quality electronics package.

    Ahren
    www.cncrouterparts.com

  18. #18
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    Oct 2008
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    Ok. $1,275 for everything but the steppers, controller, power supply doesn't seem as good of a deal to me. I'm sure it might be great for it all being metal, but I'm not that concerned with a wood-built machine. I like the Hybrid 4' x 4' and the electronics from Mike Beck for $499.

    I may be missing something, but if that is everything I need, it's coming in at about $1,000 without shipping, which is likely to be rather substantial.

  19. #19
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    The 4x4 hybrid will probably cost an additional $500-$1500 for the screws, hardware, aluminum and unistrut.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  20. #20
    Join Date
    Feb 2004
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    1086
    For $499, I would go with a G540 based electronics package. I checked out Mike Beck's site, and while it's a plug and play setup, it is unipolar, which is inefficient, and lacks a lot of the other features that the Gecko has like mid-band resonance compensation. The statement of "it's all about watts" is also not entirely true. Voltage only matters at higher speeds for Stepper motors, and it's really more about current in the ranges where motors are doing the most work.

    Even if it was all about watts, 34V x 3 Amps is substantially less than popular G540-based packages, which typically run 48V PS x 3.5 Amps/Phase motors.

    So there's another $0.02 of unsolicited advice

    Ahren
    www.cncrouterparts.com

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