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Woodpecker Woes and installing a CNC Shied instead

Discussion in 'Controller Boards' started by Richard Brooks, Mar 6, 2018.

  1. Richard Brooks

    Builder

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    Mar 1, 2018
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    Hi everybody,


    My name is Richard and I have come here looking for some advice on how to setup my grbl installation.


    I have recently purchased a small cnc - commonly referred to as a ’3018’ cnc as the working area is approx 30cm x 18cm. This whole thing comes equipped complete with a Woodpecker cnc control board.


    I should add that while the machine appears to be of reasonable quality, it has has the poorest set of build instructions I have ever come across - ever! Having been a technical author in a previous life, I do feel suitably qualified to make such a comment.


    However, I digress. So far I have managed to build the machine satisfactorily and it appears to be reasonably accurate while actually working. But, I have already managed to destroy the original Woodpecker board trying to setup limit switches and an emergency stop and adding a pendant to control the machine.


    No problem, I’ll put on an Arduino with a v3 shield and we’ll all be back at stage one again, but oh no, when I start looking around for instructions for actually setting up the new board, what do I find but utter confusion. It seems that there are so many sets of instructions on how exactly to do this seemingly simple install that anybody can do it easily.


    Suffice to say that whilst I have made some progress on this second attack to get this machine running as I would like it, there have been casualties along the way. I have managed to let some magic smoke out if one set of (A4988) drivers, but have another set in transit to me now which I hope will get me over the final hurdle.


    The thing that confuses me most is exactly how to determine the correct voltage to use when setting the Vref voltage on the stepper drivers. I can set them easily enough, it’s knowing what they should be set to!


    In short, all three motors are 17HS1352-P4130 steppers with A4988 drivers and I want to run them in half step mode at 24 volts (one jumper inserted into MS0 of each driver on the v3 board). I cant seem to find out anywhere what the Vref setting should be for this combination of Motor/Driver.


    These are the specifications for the motor:-

    Model: 17HS1352-P4130
    No. of Phase: 2
    Lead Wires: 4
    Step Angle Accuracy: ±5%(Full step, no load)
    Resistance accuracy: +- 10%
    Inductance accuracy: +- 20%
    Speed: Various Speed (Low speed)
    Step Angle: 1.8 Degree
    Rated Current 1.33A
    Rated Voltage: 12V - 24V DC
    Holding Torque: 1.26N.m
    Shaft Radial force: 2.2Kg/cm
    Shaft: 5mm round shaft
    Wire length: 30cm
    Frame size: 42mm x 42mm

    I also intend to update the Arduino Uno to use grbl v1.1f (if I can manage to find my way through the Arduino IDE software) to get the best possible experience when using grblPanel, my chosen GUI for this machine.


    If anyone could point me in the right direction on the Vref front, it would be very much appreciated - and hopefully help some other unwary person in the future.


    Many thanks in advance..


    Richard
     
    #1 Richard Brooks, Mar 6, 2018
    Last edited: Mar 6, 2018

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