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IndustryArena Forum > OpenSource CNC Design Center > Arduino > First homemade CNC Running GRBL on Arduino - Problem with settings
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  1. #1
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    Jan 2021
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    Red face First homemade CNC Running GRBL on Arduino - Problem with settings

    The machine has two HY-DIV268N-5A drivers for the x and z axsis and 2 DMA860H drivers for the y-axsis. The settings for the drivers are all at half step. That is for the HY-DIV268N-5A drivers the switches are set at "1. off 2. on 3. off 4. on 5. off 6. on" and for the DMA860H are "1. on 2. on 3. off 4. on 5. on 6. on 7. on"

    My calculations for the motors are:

    y-axsis (Pitch of 10 motors 1.8') - 200steps/10 x 1/2= 40 which gives me the code $101=40

    x-axsis (Pitch of 5 motor 1.8') - 200 steps/5 x 1/2 = 80 which gives me the code $100=80

    z-axsis ( pitch is 8 motor 1.8') - 200 steps/8mm x 1/2 = 50 which gives me the code $102=50

    It seems that I have made a mistake as the drill location on my program does not match the drill location on my material.

    I will upload a photo of the shape I am trying to cut and you will be able to see the the drill veers left and leaves my block of foam. I will also upload the G-code.

    I have been screatching my head for two days now and I would be really greatful if anyone has any advice. I will upload the g-code and some photos. Thank you so much for sharing your time and experience with a begginner like me.
    Attached Thumbnails Attached Thumbnails photo5231467323162997779.jpg   photo5231467323162997777.jpg   photo5231467323162997776.jpg   DMADRIVER.jpg  

    HYDriver.jpg   photo5230939733675323573.jpg  

  2. #2
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    May 2004
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    170

    Re: First homemade CNC Running GRBL on Arduino - Problem with settings

    First thing you should do when testing your new cnc router is calibrate the steps/mm. For each axis, jog it a set distance and measure how far it actually goes.. Then use the ratio of jog-distance to actual distance to change the $10x settings. So, if you jogged X by 100 mm and it went 200, then multiply $100 value by 0.5 (100/200).

    What you are probably missing is microstepping. It looks like you are dividing. For example, if your drivers are set to 1/8 microstepping, you multiply the number of steps by 8. But you also need to factor in screw pitch (or gear ratios for belts).

  3. #3
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    Jan 2021
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    2

    Question Re: First homemade CNC Running GRBL on Arduino - Problem with settings

    Quote Originally Posted by philba View Post
    First thing you should do when testing your new cnc router is calibrate the steps/mm. For each axis, jog it a set distance and measure how far it actually goes.. Then use the ratio of jog-distance to actual distance to change the $10x settings. So, if you jogged X by 100 mm and it went 200, then multiply $100 value by 0.5 (100/200).

    What you are probably missing is microstepping. It looks like you are dividing. For example, if your drivers are set to 1/8 microstepping, you multiply the number of steps by 8. But you also need to factor in screw pitch (or gear ratios for belts).


    Thank you that was some excellent adice! I multipled instead of dividing this time and I changed the code to
    (y-axix) $101=40
    (x-axsis) $100 = 40
    (z-axsis) $102 = 50

    I jogged the machine first at 10mm, then at 200mm, then even at 1000mm. It seems to be accurate.

    However, now when I start my cut the drill location on the computer and on the machine match, but about 40 minutes into the cut, the drill begins leaving the foam and my desegnated cutting area. I notice that the y position seems to be the same on the machine and on the computer but the x position seems to be a couple hundred mm in the plus driction of the x-axis(the right hand side of my photos of the cuts.

    The x-asis moves a lot more than y for this design. Could this be that the x is off very slightly and over the course of thousands of movements on the x-axis is a few hundred mm in the wrong spot? ?


    Maybe the x-axix coupler is somhow slipping? I may try some thread glue on the coupler today. But maybe there is something else I am not thinking of? Maybe the CNCJS program is not feeding all the comands to the grbl software on the arduino?

    Could there be another issue and is there anyway to figure out what it could be?

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