CNC size vs Design

This topic contains 9 replies, has 2 voices, and was last updated by Profile photo of Wouter Wouter 3 weeks, 4 days ago.

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  • #34922
    Profile photo of Wouter
    Wouter
    Participant

    Hi,

    Long time Lurker, first time poster.

    I have built a MPCNC over last few months, and as many are, I am impressed with the design, really well done, and thank you for making it publically available!

    I am still in the process of finetuning and figuring out the details, I intend to dissasemble the middle stack soon after I have done a few more runs, and rebuild it, hopefully it will then fit a little better.

    One issue I am having is that the designs i have made end up being milled 30 – 40% larger than I intend. Is this a stepping setting issue? I have all three jumpers installed below the stepper drivers. I haven’t been able to find any comments about a size change issue.

    I have used Aliexpress electronics, Ramp 1.4, DRV8825 and smart LCD. I am using ESTLCAM to convert Inkscape made SVG files, and printing via Pronterface.

    Appreciate your feedback to see if I can get atleast similar sizes between design and end part.

    thanks
    Wouter

    #34923
    Profile photo of Ryan
    Ryan
    Keymaster

    Are you using 20 tooth pulleys instead of 16?

    Thanks for the kind words!

    #34924
    Profile photo of Wouter
    Wouter
    Participant

    I ordered 16 tooth pulleys, and then didn’t count them but i will check that I did receive the right ones.

    #34925
    Profile photo of Wouter
    Wouter
    Participant

    Ók, so thats the issue. I ordered 16 teeth pulleys and received 20 teeth pulleys!

    Is it an easy change to update the software to reflect 20 teeth instead of 16? Is it something i can do myself?

    #34926
    Profile photo of Ryan
    Ryan
    Keymaster

    Yes just update the x and y steps in the firmware.

    #34927
    Profile photo of Wouter
    Wouter
    Participant

    Is it only changing:
    #define DEFAULT_AXIS_STEPS_PER_UNIT { 200, 200, 4535.44, 200 } //MPCNC

    to

    #define DEFAULT_AXIS_STEPS_PER_UNIT { 160, 160, 4535.44, 200 } //MPCNC

    in the configuration.h?

    #34928
    Profile photo of Ryan
    Ryan
    Keymaster

    Yes, perfect.

    #34929
    Profile photo of Wouter
    Wouter
    Participant

    Fantastic, this has solved my size problem! On to the next one!

    Thanks for the support!

    #34930
    Profile photo of Ryan
    Ryan
    Keymaster

    What, no next one…positive attitude. Get ready to get it dirty and have fun and maybe learn some things along the way.

    #34931
    Profile photo of Wouter
    Wouter
    Participant

    I like to fight it first, see if I can figure it out.. Have some positioning issues to work on, in terms of how well layers are on top of eachother, but i think that is refitting the centre assy, and making sure belts are tight etc. I will be back!

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