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  1. #1
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    cnc pic

    hello all,
    iam trying to make a small CNC engraver.and searched a lot for easy and simple circuit.as my engraver is small i want to use steppers from old printers.
    at last i decided to use PIC16LF84A based stepper driver from turbocnc site (http://www.dakeng.com/u2.html).below is my modified diagram for 3-axis.

    mean while i found another design based on PIC16f84 and ULN2803 (http://eehk.net/archiver/?tid-1249.html)
    now iam confused which one is good.
    i have NOPPP programmer to burn PIC16LF84A.
    so guys can u guide me with this issue.

    help me pls.i'll be waiting for your replies.
    thanks

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  2. #2
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    cnc driver circuit

    I am also in the process of making one myself for cnc milling and drilling of pcb.
    However I'm stucked with the mechanical parts of it which quite difficult to obtained.
    On the 3-axis stepper driver I plan to built the Linistepper driver which have microstepping and looks like having smoother control on the stepper motor.



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    cnc picstep microstepping controller 3 amp

    yes surely it looks like some good driver.
    but iam unable to find it pcb layout for developing the circuit.do u have any eagle files and hex code for pic(16f84) so that i can directly go for building..



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    linistepper

    well i haven't get any replied for LINIstepper.
    so any more idea for good stepper drivers?
    and which one the circuits u think capable of taking more current(look at my first post)



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    pic cnc

    Sorry for late reply, i got the hex file but the pcb hv to be fabricated on our own.
    I hv re-designed it in Protel format but not having enough time to built and test it.
    Pm me if you can operate Protel.



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    cnc con pic

    well there are some user modified linicontrol in PICLIST.one of them is Posix's controller.it uses PIC16f628 and some other pcb layout than current controller.have a look(he provided eagle layout for easy development) http://www.piclist.com/techref/io/st...istep/mods.htm

    but i have some doubts in it.
    1.he did't provided any code for F628
    2.does it need any break board(between driver and parallel port) ?
    3.and in the below pic.what are these connections for



  7. #7
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    parallel port breakout board circuit diagram

    The file supplied also contained codes for 16F628, the connectors are for Mode and power selections. Crystal frequency is 16MHz.
    Yes using a breakout box is neater than hard-wiring to the parallel port.
    In fact all is explained in the PIClist you just hv to read all of them.



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  8. #8
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    simple pic chip engraving machine projects

    thanks for the reply.
    i collected all the info for making Linistepper(made by posix).and posting it as a pack.have a look.
    the code is is posted by the author himself.but when i tried to load it in to pic programming it shown me some error.

    u said the code is made for both f628,f84.that mean without modification i can use it for F628?

    scroll down in the below page u'll find code.so can i burn that HEX directly on chip(f628)?

    http://www.piclist.com/techref/io/st...step/index.htm



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  9. #9
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    cnc+pic

    Not sure about this but in the zip file I posted contained lini_f628.hex which you should load into the programmer. There should be no change in the h/ware.



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    pic+cnc

    nice.i'll do that.
    one more problem iam facing is with stepper motors.
    i have several motors reclaimed from old printers.problem is i don't have any spec of them.(nothing is written on them).have a look at the below pic and any idea how much min-max voltage i can feed them?
    http://img408.imageshack.us/img408/9...89smalltw8.jpg
    http://img176.imageshack.us/img176/3...91smallmn4.jpg



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    pic programming 3 axis cnc

    You hv to identify if they are Unipolar or Bipolar type.
    Unipolar usually hv 5 or more wires and Bipolar hv only 4.
    Linistepper can only drive Unipolar type.
    You can hv more info from this link.

    http://www.doc.ic.ac.uk/~ih/doc/stepper/



  12. #12
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    picstep

    ru also working on this project ?

    i found every thing i need except the break out board.i mean board between parallel port and the driver circuit.it will be quite safe to make a opto based board.(my design skill sucks.so if some one already worked on it pls do post)



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    linistepper eagle

    I hv no problem with the stepper controller, as I said earlier I'm stucked with the mechanical parts.
    I'm thinking of retrofitting a mini milling mc (like X2) would be another good idea instead.



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    pic16lf84a programmer

    i did some research in the past and here are some interesting links
    http://www.fromorbit.com/projects/picstep/index.php
    http://www.pminmo.com/



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    picstep nema 23

    thanks.
    but i felt linistepper is easier to built than picstep,and pminmo's stuff is also good.

    one more thing abt the linistepper is R1,R2.these two are chocking resistors right(to limit current to the motor when we are running them at over voltage).but when i run them at exact voltage do i really need them? can i just solder a wire instead of those 2 resistors?

    @dindeds
    at what step rate ur using the controller.is it running ok or getting hot.and have u made any break out board for it?



  16. #16
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    cnc with pic

    R1 & R2 is for limiting the current to suit the motor being used. You hv to take into account the motor phase resistance & current. Shorting this resistors will pass ~5A through the motor coils (TIP122 Ic max).Even if the motor can take it, the transisotrs would not.
    My stepper running slightly warm without load (about 15 mins) - using stepper from an old printer. I want to use it with NEMA 23 size stepper motor when I hv the budget.



  17. #17
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    16f84 cnc drÄ°ver

    usually motors from printers don't hace spec. written on them.so how much resistance/wattage ur using.
    all i can do is trial and error for resistance to be used for my motors.(they r kind big-above pic-so i think 12v is the best choice).



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  18. #18
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    posix linistepper help

    Right, I spent hours myself trying to figure that out too.
    Then I decided to built one simple standalone stepper driver circuit so I can test any unipolar stepper motor.
    Here's a good one from Kitsrus which uses std parts.
    I built one with PIC controlled which hv the same functionality.



  19. #19
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    cnc pic driver

    yes its a very good idea to confirm abt the motor details.i had exactly same issue in my mind.
    and as i already have pre programmed pic16f84's and ULN2803 i would like to try modified dakeng's circuit. (http://bao625.no-ip.com/cnc2-1.jpg)

    and another point that i saw in linistepper site,is abt tuning the motor
    Finding the max efficiency point is quite easy:
    * make sure low power input is set to full power
    * start with psu voltage a few volts higher than the rated motor voltage
    * run the motor at a typical speed
    * using a variable psu and amp meter;
    * slowly reduce the voltage until the amps drop suddenly
    * the voltage JUST before the amps drop is the max efficiency (min heat)
    nice idea is'nt?



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