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Help needed with $100 and $ 101 setting (STEP/MM)

Discussion in 'CNC Mills/Routers' started by Akash, Nov 30, 2017.

  1. Akash

    Akash New
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    Hi ,

    I’m using an ox cnc with x pro board with default 1/8th micro stepping and using NEMA 23 1.8 degree (200 Steps per revolution)



    I’ve noticed that my circles are not proper. I tried recalculating the $100 and $101 values which was set to 26.667 as default.

    I tried using the formula that’s in the github web site

    steps_per_mm = (steps_per_revolution*microsteps)/mm_per_rev

    = (200*8)/ MM_per_rev


    But I’m stuck in the “MM Per Revolution” as I cannot find it anywhere how much it travels per revolution


    Please help me .

    Thanking You

    akash
     
  2. Jonathon Duerig

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    You got me to click on this conversation because I thought it was about money! Sneaky! Hahaha.

    Seriously, though, the exact values you need depend on your precise setup. If you are using belts, it is the amount of teeth in the pulley, the pitch of the belt and even how much tension is in the belt. So the best thing to do is to actually measure the value.

    - Take each axis independently.
    - Clamp a piece of scrap right next to the plate.
    - Jog the machine away from the scrap until it is about as far away as you can measure with calipers.
    - Use a pair of digital calipers to measure the actual distance travelled.

    Now you have ratio between the actual distance travelled and how far you travelled according to the jogging you did. You take your current steps/mm value and multiply it by that ratio. Now you have a new steps/mm number you put in. And then you run the test again to see how well you did.

    I always forget whether to multiply by actual-distance/jog-distance or jog-distance/actual-distance. But there are only two possibilities and it will be obvious if you put in the wrong one.

    While you are doing this, just record everything you do as you do it on a piece of paper and you should be able to get to a reasonably calibrated result very quickly.

    -Jonathon Duerig
     
    Retrosmith and Akash like this.
  3. Akash

    Akash New
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    ;).. hey thanx . Your solution seems something that my head can take without overheating..
    I'll check and will let you know
    $thanx
     

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