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Thread: CNC for dummies

  1. #1
    Join Date
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    Default CNC for dummies

    Anyone know of a good read for CNC for dummies...

    I already know the theory behind CNC and how it works but not the hardware used....

    I looked at CNCzone but that has to be the most god awful forum to attempt to navigate and I gave up in disgust after seeing the 10 000 different forums (and no beginners forum) they have..

  2. #2
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    Quote Originally Posted by Ringer

    I looked at CNCzone but that has to be the most god awful forum to attempt to navigate and I gave up in disgust after seeing the 10 000 different forums (and no beginners forum) they have..
    LOL but even if they had they would post in all the other ones

    I don't know of one, we give talks at shows and clubs and they are very well attended and people tell us they have learn a lot.
    There is a lot of interest in that we always have a full hall at the shows and only a couple more subjects, painting and casting do the same.
    I think a book would be hard as the technology is moving so fast.
    take drivers, what was for sale a year ago is now being superceeded.

    I could go thru the basics if there was any demand.
    One main problem is the names and what they do, as an example Mach3 is a CONTROLLER as it the program that controls the machine but because it has wizards and lazy cam included people often call it the CAM program which is totally different.

    .
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.




  3. #3
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    Clearwater,FL USA
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    Ringer,

    You might want to check out the MechMate forum. The size of the forum is smaller and only geared to one machine but they give great info. Some of the post go into how to pick a stepper motor for a specific driver and such.
    Link is www.mechmate.com/forums/index.php


    What are you trying to convert or build?

  4. #4
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    You can't cleanly separate the various functions. Controllers like Mach do minor design. CamBam is partly a CAD program. Even SketchUp can generate G-code from several different plugins.

    I think though that Ringer wants to know about the hardware options.

    Steppers, Integrated driver/steppers, step and direction servos, pure servos with drivers, closed loop steppers vs open loop, Driver capability in amps vs type of steppers and power supply requirements and so on.

    I don't know of a book or even online source where that information is collected all in one place. I wouldn't try to write one either as it would be out of date by the time it was published. Anything that deals with the hardware faces the same problem because the technology and the vendor base shifts constantly. For instance, there are now widely available stepper motors with inbuilt drivers and closed loop position feedback that makes them close to being a servo. In fact they are a type of servo since the term "servo" is defined by the presence of a positional feedback system.

    There are many details for which it is hard to find good references that clearly explain how it all goes together. You need to scrape up bits and pieces from numerous sources and try to figure out how it all falls together.

    This is particularly the case if you are attempting to design your own system but still applies if you want to retrofit a manual machine. Some of the considerations are quantifying the amount of torque required to drive the system. This includes such difficult to define variables such as the inertia of the rotating components like lead screws. Information on these topics is available but can be hard to find.

    I have a huge compendium of such information but I can't put it online because most of it is under copyright to someone else. This is a major problem that make it very hard to provide one stop shopping for information.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  5. #5
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    You could ask the suppliers,Larken and Keling are helpful at this.

    http://www.larkencnc.com/

    http://www.kelinginc.net/

    Or you can maybe decide just how much power you need,pick a driver and build according to it's specs.

    This one from Keling is one I am going to use-

    http://www.kelinginc.net/KL-11078.pdf
    I just need one more tool,just one!

  6. #6
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    That's pretty funny. I did a search in Amazon three days ago for a CNC for Dummies book and was surpirsed I did not find one. I just bought an old Boss 4 so I am looking for the same info. Just like everyone said it is hard to find informtion out there and now I know why.

    CNCZone is annoying with the 5000 forums, but the people seem helpful enough.

    I would love to see a high level over view from a hardware persepctive, even if it was in generic terms.

    I see a lot of cheap NEMA23 motors and controller boards (or are they driver boards ?) on EBay from companies like Long Motor from China. I don't know how I would calculate what I would need intetrms of power supply for voltage or current per phase on the stepper motors to get a decent speed or IPM.

    Seems like you need to know what you don't know to figure out what you don't know

    Regards,
    Kevin

    I plan on going to Cabin Fever in January so maybe the demo by littlemachineshop will help.

  7. #7
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    I am going to sift through my banks of data and see what I can put online. Some of it is in data sheets from manufacturers and they explicitly allow it to be redistributed. Other material has been put in the public domain or is freely distributable so I will see what I can find and organize it in my reference library on my web site. I will post about it when I have it ready but it may be a week or two. I'n not sure just how much there is that I can put up but there will be some good information.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  8. #8
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    I can give you a brief history and methods that have been used, but there are many variations.
    The first types of commercial CNC systems used a proprietary computerized system to control the CNC or interpolated servo motion, plus G code programming via servo motion control side of the system.
    This system communicated with an external controller which could be relay or PLC logic, this unit controlled the machine control or M codes, this would include tool changer, coolant, spindle, via program S,T,M codes.
    Both of these systems would communicate via a physical I/O port on the MB.
    Later systems had the PLC built in and used a common bus to communicate over.
    This led to manufacturers of motion cards that would fit in a PC slot such as Galil, Acroloop and Delta-Tau, these closed the CNC loop via encoder feedback directly to the card, some had built in PLC others required either external or a PC based PLC, the operator interface, of course was the PC itself.
    In order for CNC control to be in the reach of the average hobbiest, led to PC based systems such as Mach, EMC etc.
    The Mach system used step and direction servo/stepper control through the PC parallel port and is completely software based, another difference here is the control loop is not closed back to the controller, only to each servo driver, so this precludes features such as electronic gearing and electronic cam that the closed loop boards can offer.
    IOW, the computing part of the system cannot track servo's position it outputs position control blindly and relies on each motor controller to faithfully follow its commands.
    I/O on Mach is limited if using the P.P. only as it has limited I/O, a secondary P.P. can be used to increase I/O in this case.
    There have also been PC based systems that has used one of the proprietary LAN bus systems, in this case the servo drives, PLC I/O etc all use communication over the bus.
    Hope this enlightens a little.
    P.S. Is there any particular Hardware you are looking for info on?
    Max.
    Last edited by MaxHeadRoom; 10-03-2010 at 11:04 AM.

  9. #9
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    Best way is the school of hard knocks. I did not have any experience with CNC's or Machining but had to learn or else! The operator manual will be the best source, I can reccommend the Haas training/operator manuals, these are excellent. Haas machines comply with international G code standards so its relevant to most modern machines.

  10. #10
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    Here is a first contribution complete with easy to implement BASIC programming to control a stepper. All you need to follow the programming is Microsoft Excel. Don't dismiss the programming part out of hand. It is an excellent way to learn exactly how things work and it isn't hard to follow. I wrote my own controller software for the plotter I built back in the 80's.


    Understanding various types of Stepper Motors
    And
    Controlling it through Parallel Port

    It's by a first year university student and explains things fairly well. The file is a zip file which I have renamed to .zap to avoid download filter problems. If you download it then just rename it to .zip and then extract it or just open it. It will open in Wordpad just fine.

    http://ixian.ca/server/Stepper_Motor.zap
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

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