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IndustryArena Forum > Other Machines > PCB milling > diy CNC drill alignment problem
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  1. #1

    diy CNC drill alignment problem

    I have made a homemade CNC for double sided pcb protoyping. I use flatcam to convert excellon files in gcode and then use UGS to send this gcode to arduino. I tried to drill a pcb size 180x140 mm having four registration holes in the corner, but when i match the drilled PCB with the printout of excellon files they don't match.

    [image]
    the red outline shows the drill being matched

    [image]
    drills in flatcam

    I tried to calibrate the CNC axis but the result is same.

    I also tried to check whether the print is proper or not, so tried to print in landscape orientation as a result most of the drills match but some do not.

    What possibly be the solution of this error?

  2. #2
    Join Date
    Apr 2005
    Posts
    304

    Re: diy CNC drill alignment problem

    Never trust your printer!
    Make no mistake between my personality and my attitude.
    My personality is who I am. My attitude depends on who you are.

  3. #3
    Join Date
    Feb 2013
    Posts
    48

    Re: diy CNC drill alignment problem

    Hi Kernel,

    Have you read some of the solutions given under the thread https://www.cnczone.com/forums/pcb-milling

    Remember to provide a picture of your CNC setup, such as stepper controller, Spindle motor specification, Power suppy and
    any Gcode software driving the CNC milling machine.

    Without some these inputs I very much doubt if you will receive proper response from the community.

    Cheers,
    Hanspeter.

  4. #4
    Join Date
    Nov 2012
    Posts
    1267

    Re: diy CNC drill alignment problem

    Take a steel ruler or a caliper and measure the distance between two known points. First on the printout, then on the actual PCB. Which one (if any) is correct? Most printers are not geometrically perfect "out of the box".

    Also check the 90-degree angle between your X and Y axes. Make a test drilling: 4 holes in the corners of a large rectangle. Measure the sides and the diagonals of that rectangle. If your X and Y are not perpendicular to each other, the diagonals will have unequal length.

  5. #5

    Re: diy CNC drill alignment problem

    Is there any way to check whether the printer is printing correctly?

  6. #6
    Join Date
    Feb 2013
    Posts
    48

    Re: diy CNC drill alignment problem

    The short answer, your CNC could be loosing steps.

    Did you follow CitizenOfDreams guide?

  7. #7

    Re: diy CNC drill alignment problem

    Quote Originally Posted by HPB View Post
    Hi Kernel,

    Have you read some of the solutions given under the thread https://www.cnczone.com/forums/pcb-milling

    Remember to provide a picture of your CNC setup, such as stepper controller, Spindle motor specification, Power suppy and
    any Gcode software driving the CNC milling machine.

    Without some these inputs I very much doubt if you will receive proper response from the community.

    Cheers,
    Hanspeter.
    Hello Sir,

    I am using Arduino UNO based CNC shield, mounted with DRV8825 Stepper Drivers, GRBL v1.1 Firmware and Universal G-Code Sender(UGS) to driving the machine. The whole machine is powered with an SMPS of 12V, 10A and spindle has its own SMPS. I have attached the picture of CNC setup and Stepper controllers as well.

    The spindle motor is of 12000rpm, the below link will provide more specificatios;
    https://www.banggood.in/Machifit-ER1...r_warehouse=CN

    Thanks for your reply.

  8. #8

    Re: diy CNC drill alignment problem

    Quote Originally Posted by CitizenOfDreams View Post
    Take a steel ruler or a caliper and measure the distance between two known points. First on the printout, then on the actual PCB. Which one (if any) is correct? Most printers are not geometrically perfect "out of the box".

    Also check the 90-degree angle between your X and Y axes. Make a test drilling: 4 holes in the corners of a large rectangle. Measure the sides and the diagonals of that rectangle. If your X and Y are not perpendicular to each other, the diagonals will have unequal length.
    Hello Sir,

    I have made a test drilling of rectangle 190mm*140mm with various drill points across perimeters as well in centre. I have also attached the result of drill output compared it with print.

    To check the 90-degree angle between x-axis and y-axis I have performed Pythagorean Triples Algorithm as guided by this video, link; https://www.youtube.com/watch?v=lU0iZKajpoo
    I choose 18, 24 and 30 as triplets. First jog the x axis to 240mm taking a reference point, then 180mm in case of y-axis. After measuring it by scale, I found it is 239mm on x axis, while 180mm in y-axis, and as well it was also showing 300mm. Is the axis are off square?

    Thanks for your reply.

  9. #9
    Join Date
    Apr 2005
    Posts
    304

    Re: diy CNC drill alignment problem

    Diagonals are best checked at the extremes of the machine travel.
    i.e. 0,0; 0,Xmax, Xmax,Ymax, 0,Ymax.
    If you have diagonals of different sizes, then you first need to square your machine, then calibrate it (there is a video how to calibrate nachine on CNC Nutz channel also).
    And as I already wrote: do not trust your printer.
    Make no mistake between my personality and my attitude.
    My personality is who I am. My attitude depends on who you are.

  10. #10
    Join Date
    Feb 2013
    Posts
    48

    Re: diy CNC drill alignment problem

    Kernel,

    I understand you're concern with milling a copper clad board hence your measurement area.

    Drills and measurement looks ok from where I'm sitting
    Hope you marked that area out so you always place your PCB in there for milling and drilling.
    Ensure you first place a sacrificial board about 1mm thick so you don't drill into your bed.

    From your picture X gantry look rather heavy, I hope the Z axis does not loose steps due gravity, what
    happens is, milling bit will dig deep into PCB substrate and end up with a broken bit.

    Try and download FlatCAM, it's pre-processor software that allows you to set Z axis depth to cut, tool tip diameter,
    number of passes around copper tracks and pads.
    It will process your Drill data too.

    I am using Arduino UNO based CNC shield, mounted with DRV8825 Stepper Drivers, GRBL v1.1 Firmware
    This is exactly my setup except that I use OpenCNCPilot as this probes surface of PCB for unevenness and applies it
    to your G Code Z axis data, next you mill out your tracks and pads. Note OpenCNCPilot is an open source software that sends
    your G code to Arduino UNO running GRBL v1.1F.

    Go head and mill your first PCB.

    Cheers,
    Hanspeter.

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