URGENT : looking for some PLC/uC based CNC projects ideas

Discussion in 'The Projects Forum' started by LETITROLL, Dec 13, 2013.

  1. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    Hello everyone here , am in desperate need for some ideas on PLC based CNC projects , i mean machine that is controlled numerically by computer and using Programmable logic controller or simply a PIC microcontroller .

    THE PROBLEM IS I DON'T HAVE A CLEAR IDEA ON WHAT TO CHOOSE .

    Please share your ideas ! , if possible a project that is not very complicated and very useful in modern industry .
     
    Last edited: Dec 13, 2013
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It seems a backwards way of selecting a medium?
    Usually the overall scope or requirements of a particular project governs the most efficient or optimum methods used for it to come to fruition, and in many cases, cost is also a deciding factor.

    The three methods you describe are machine control by CNC etc, At the basic level a PC is often used for this for its computation power in conjunction with its very powerfull ability for Operator Interface or HMI.
    An open source PC based CNC controller is the LinuxCNC.
    A PLC would not normally be used for this type of control just because it does not generally have the power for servo integration and interpolation.
    It would be used however for point-to-point control of industrial devices and semi-complex control, the features of the PLC include already conditioned I/O that can take the form of contact closure, transistor, SCR etc.
    There are also Touch screen HMI that can interface with most PLC's.
    Another advantage in PLC control is the ability for maintenance personnel to trouble in simple ladder logic fashion.
    And lastly is the MicroController which is often a very cost effective way of smaller powerful project control, this method requires some degree of programming knowledge in one of the compatible languages and also the integration of 'real world' devices, in designing the I/O interface.
    This rambled a bit, but it may help in choosing which direction you want to go. .
    Max.
     
    Last edited: Dec 13, 2013
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  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Just google DIY CNC.. There are thousands of builds out there.. From Grbl based Arduino projects to Tinyg (my favorite) to EMC/Linux to whatever..
    reprap..
    grbl
    openpnp
    blah blah blah
     
  4. MaxHeadRoom

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    If purely PC CNC is required then another starter is Mach3, free for up to so many lines of code.
    Max.
     
  5. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I am currently designing a single axis custom solution around an Omron CP1L PLC to control a servo (actually a stepper driver). The CP1L lends itself well to such a task. Actually it is designed with such tasks in mind; It has high speed pulse inputs & outputs - 4 axes of inputs and 2 axes of outputs. The CP1H has 4 axes of outputs.

    My project does not employ any G-Code. I am not sure how easy it would be to implement G-Code in the Omron PLC, but I suspect not very easy. This is why CNC usually uses it's own CNC purpose-made controls, not a PLC.

    I am considering making a DIY multipurpose 5 axis CNC skeleton, and at this time I am not considering using a PLC for this. I will most likely use a PC, running some flavor of software, communicating with a CNC controller board, and drivers.
     
  6. MaxHeadRoom

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    Generally PLC are not used all that much in CNC, because of the update time and not able to do interpolation, they are often included for I/O, M-code use etc.
    Maple Systems have some nice HMI's for most PLC's out there, including touch screens.
    Max.
     
  7. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    Thanks .

    I see that you have an idea about this .

    What we are working with here are two types of machinning actually :


    Type one

    is a machine that has a cycle that repeats itself over and over
    , for example a bottle filling machine .

    Type two
    Machine that executes a process automatically after telling it what to do using a control witch is CNC , for example :
    http://www.youtube.com/watch?v=02flL5izS0U


    So right now what am planning to start is something similar to the project in the video , but instead of a knob , modeling small gears , with an CNC controlled sharp cutter , just like this system :

    http://www.youtube.com/watch?v=mAsp3_uN7SY

    So what you think about this one . ???
     
  8. MaxHeadRoom

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    Jul 18, 2013
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    For the Bottle filling example, typically this would be done with a PLC with the suitable I/O modules and sensors required.
    For the CNC, do you intend building your own machine? Or just interested in the process required?
    The first machine sounded as if it was via stepper positioning by the sound of it?
    If you want info on building a CNC system it would pay to join one of the DIY Forums.
    Mach3 forum, LinuxEMC, CNCzone for a few.
    For an off the shelf CNC, there are few table top machines available.
    Max.
     
  9. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    Am working with 3 persons , together we will design and build our own cnc machine .


    Am really interested in the gear cutting machine ( multi form cutting ) .

    So if i can build a system that cuts parts ( not very complicated shapes ) according to a 3D sketch designed by a 3D modeling software , this would be really nice , but of course if its going to be too complicated and expensive to build , we can make a machine that cuts simple metal parts ( round , square , triangle ).


    Am just worried about the ability of the cutter to achieve a performace identical to the 3D element .
     
  10. MaxHeadRoom

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    If you are thinking of Milling gear cutting etc, then I would advise buying a Mill (3 axis) rather than a router type machine as it will not be rigid enough, if you want to put your own system on, you will need to replace any acme screws with Ball screw type positioning, the software decides whether it will be 2 1/2 axis or 3 (3D) machining.
    2 1/2 is 2 axis interpolation between any two selected axis and the third linear movement, as in the video links you included.
    3D is interpolated motion of 3 axis.
    Max.
     
  11. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    Hey max , i will get back at you later .

    Am really appreciating your time .
     
  12. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    Ok please i want to know what software is used with this type of machine, and also how the cutting is controlled with it with respect to a pre-designed metal shape ???

    I want to go as basic as possible at first , that means i want to perform cutting of simple shapes , and then when i go further on my project i will do shapes similar to a gear for example .


    Am sure if we get this thread on the road we can get to some great results .
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you want trial software for a low cost, then the trial version of Mach is free up to a certain line of code count.
    This is PC based S/W. that operates stepper or servo drives off of the Parallel Port.
    It is basically open loop system, i.e. the trajectory planner and HMI do not monitor the actual servo loop.
    If wanting a little more powerful add on to this, check out Dynomotion for a USB external extension which does offer closed loop.
    Or there is LinuxEMC, free, open source.
    The above and most CNC use the standard G-code M-code programming.
    For complex shapes, the customary method, rather than G/M code is to use a CAD/CAM package, this takes a CAD program and the CAM converts it to a tool path machining program and converts it to a G-code program.
    It pays to learn G-code anyway, for tweaking a CAD program simple programs, a use full book for this is one by Peter Smid ISBN 978-083113347-4
    Max.
     
  14. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    OK i see.

    SO the G-code will help out setting the environment between the machine and the software , making the cutting surface totally controlled by the PC numerical control.

    For that i should design a cutting area where the metal surface is placed , lets say about :
    40*30 centimeters
    And i need a hand that will be moving across this area , with the help of 3 stepper motors , each one placed in one axis , those would be of course moving forward and backward .

    like this one :
    [​IMG]

    But would g-code and mach3 be sufficient for my application ???
    And am i imagining things the right way or am wrong , please correct me if am wrong.
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
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    With the machine shown you will not be able to do much in the way of heavy machining and limited to very small gauge metal, and mostly aluminum.
    A router gantry machine like that is intended for wood and light aluminum sheet due to the rigidity, (or lack of) of the machine, also you are limited in the Z axis (downward) travel.
    For larger steel machining you need a bench or knee mill.
    For a simple introduction Mach would be plenty, the free version is downloadable and you can actually run a program and play with it to see the example, before attached to a machine.
    Normally the machine you show is a 2 1/2 axis where the X,Y, is interpolated and the Z the 3rd linear axis.
    Although you can chose any 2 axis for interpolation by G code.
    Max.
     
  16. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    3D simulation would be really helpful , i will take a look at the software .

    As for the axis setup , i want the head to be moving around inside the predetermined process area , for example : the head's cutter must be able to get downward and upward to be able to make an entrance on the metal surface according to a certain thickness , should also move left and right and move forward and backward to perform the cutting of the desired shape .

    So what axis configuration should i implement , also how many steppers do i need and what type ???
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You will need 3 stepper motors and drives, I do not use steppers personally but there is quite a bit of info on the Gecko drive site.
    Mach will do 3D they also have a built in CAM system that converts different file formats.
    I suggest you download the free copy and do a simulation.
    You most likely will have to set the I/O and E-stop to allow you to run a file.
    Max.
     
  18. LETITROLL

    Thread Starter Member

    Oct 9, 2013
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    I have downloaded a cracked version of mach 3 , so all i need is this software and g-code language ???
     
  19. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Mach has its own CAM program which converts different CAD files to a CNC program OR you can program manually in straight G/M code if you wish.
    Max.
     
  20. LETITROLL

    Thread Starter Member

    Oct 9, 2013
    218
    2
    After doing a search on the components to be use , i have found some old matricial printer steppers like this one :

    Can this be used for the 3 axis movement of the metal cutter ??? are thy powerful enough .
    [​IMG]
     
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