Thread: Cnc for dummies

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  1. #1
    Hi,can anyone suggest a suitable beginners guide to cnc, which explains the most basic components and their applications. As far as electronics are concerned, i can put a battery in a torch, change a fuse, and that is about it.When i read your various build details, the mechanical parts are not a problem, but as a complete novice when it comes to electronics components and their function i would dearly like to learn from absolute basics onwards.So if anyone can help it would be much appreciated.

  2. #2
    OK I'll try in words of 1/2 a syllable.



    Start bottom left with an idea of a part. This is then turned into a drawing in a CAD program, passed to a CAM program that writes the G Code and then loaded into a PC that also runs a controller program like Mach3 or EMC.

    This in turn spits out a series of electrical commands via the parallel port to a breakout board.

    The purpose of this is to protect the computer from any unwanted reversed voltages and also to get a clean signal as a lot of computers output low voltage on the parallel ports and this boosts the signal.

    The clean signal is now sent on to a driver who's job it is to amplify the small logic signals into heavier current for the motor. Simply put you get two wires per driver, step and direction.
    step is a pulse that makes the stepper motor work, most require 200 full steps per motor revolution. Direction is which way it has to go.

    From the driver the current goes down the cables to the motor, motor is connected to an axis.
    In the drawing only two are shown but more is only a duplicate of driver and motor.

    Looking over all this is a power supply that gives various voltages out as needed for the components, the main one being the stepper driver supply.

    Very rough and ready and can be expanded on but that's the basics.

    .
    John S -

  3. #3
    Quote Originally Posted by MIAPISH View Post
    As far as electronics are concerned, i can put a battery in a torch, change a fuse, and that is about it.
    Sounds just like Moi :heehee:

    I must admit BuildYourCNC was a huge help in understanding how it all went together when I started out. John's diagram might look simplistic but it is accurate. There really is not a lot to the wiring unless you want to get into building your own drivers etc

    I bought a kit from Zapp, followed the wiring diagram and it just, well, worked! You could always try that approach.

    Regards, Jeff.
    Nothing is foolproof......to a sufficiently talented fool!

  4. #4
    Quote Originally Posted by John S View Post
    OK I'll try in words of 1/2 a syllable.



    Start bottom left with an idea of a part. This is then turned into a drawing in a CAD program, passed to a CAM program that writes the G Code and then loaded into a PC that also runs a controller program like Mach3 or EMC.

    This in turn spits out a series of electrical commands via the parallel port to a breakout board.

    The purpose of this is to protect the computer from any unwanted reversed voltages and also to get a clean signal as a lot of computers output low voltage on the parallel ports and this boosts the signal.

    The clean signal is now sent on to a driver who's job it is to amplify the small logic signals into heavier current for the motor. Simply put you get two wires per driver, step and direction.
    step is a pulse that makes the stepper motor work, most require 200 full steps per motor revolution. Direction is which way it has to go.

    From the driver the current goes down the cables to the motor, motor is connected to an axis.
    In the drawing only two are shown but more is only a duplicate of driver and motor.

    Looking over all this is a power supply that gives various voltages out as needed for the components, the main one being the stepper driver supply.

    Very rough and ready and can be expanded on but that's the basics.

    .
    Very helpful,sorry abut the delay in answering, just got back from hols.

  5. #5
    This is just the type of info. needed to decide whether to proceed with a project. Being of somewhat advanced years i take a little longer to absorb tech. info. these days, and i appreciate your time and approach o the question. I now need to research info. on the various steps you have described.Many thanks again.
    Dave.

  6. #6
    Cheers Smiler, it`s nice to realise that not everybody is a genius when it comes to understanding cnc ciruits etc. i will take a look at your suggested links, and thanks for the reply.
    Dave

  7. #7
    Hi, i will carry on using the net, just thought i could speed things up a little by asking the experts.I hope that being possibly a `backward type` doesn`t cause too many problems.
    Dave

  8. #8
    Owen.gray's Avatar
    Location unknown. Owen.gray Last Activity: Has a total post count of n/a. Referred 6244 members to the community.
    I sugest you look at E-BAY they have cheep boards that have the step out board and drivers all in one all you supply is a power supply and a comp and mottors (MAKE SURE THAT THE BOARD CAN HANDLE THE CURRENT OF YOURE MOTTORS) and you are away price around 60

  9. #9
    One problem with these combined boards for a beginner is they look good with being cheap but one mistake, easy for beginner and experienced user, [ don't ask ] and you have fried the lot.
    Many of these cheap boards come direct from China with zero support.

    The result is many beginners loose heart and drop the project.

    Roy at http://www.diy-cnc.co.uk
    used to do a combined board, the system 3 but dropped it in favour of the System 4 that has plug in cards, fry an axis and you are just the driver card out of pocket.

    Believe me when I say drivers are the weak link in a CNC system and that is one reason not to skimp on this component.
    You need a reliable driver that has support.
    John S -

  10. #10
    I for one will never buy anything that is all in one, separates in a box is OK as you can then repair or replace just the dud one.
    A bit like break one egg you can still make an omelette but if they were all in one you cant make it! If you get my drift!
    The other bit is you need to up the power on one axis you just get the one with extra power and keep using the others.

    My 2p
    Peter

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