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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > How do I make CAD/CAM size match machined size?
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  1. #1
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    How do I make CAD/CAM size match machined size?

    Greetings! I'm a newbie at this, literally my first post so bear with me...

    I have a Sherline mill, I'm not sure what model.
    I got it working in Mach 3.
    I can move the 3 axis's manually and I've figured out how to reset the x, y and z to zero.
    I have figured out how to load a gcode file and make the mill run it.

    I am using CorelDRAW 12 to make basic shapes.
    I've figured out how to use MeshCAM V3 to create a gcode file.

    My question is - How do I make the same size in CorelDRAW when the shape is machined? I ask this question because I made a simple circle in CorelDRAW that was 1 inch by 1 inch.
    I exported to a .png and imported into MeshCAM. I told MeshCAM that the file was 1 inch by 1 inch.

    I ran the gcode produced in Mach3 and the circle was soooooo small! Nowhere close to an inch!


    Does anyone have a Gcode "Ruler" program that I can run through what will correspond to real inches/mm?

    Also, can anyone share with me the software they use to go from Idea to Gcode?
    Attached Thumbnails Attached Thumbnails 101_1766 (Medium).JPG  

  2. #2
    Community Moderator ger21's Avatar
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    I am using CorelDRAW 12 to make basic shapes.
    I've figured out how to use MeshCAM V3 to create a gcode file.
    What most prople do is export a vector file, like a .dxf, and use a 2.5D CAM program, like the free LazyCAM that comes with Mach3, or Vectrics Cut2D to create the g-code. That's the most accurate way.

    Doing what you're doing with MeshCAM is a completely different process. However, if you tell MeshCAM it's 1", it should cut 1".

    Are you sure the machine is cutting the correct size? Are you sure it moves 1" when you tell it to?

    In the .png file, is the circle the full size of the .png, or just a small portion of it?
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  3. #3
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    Draw the circle with MeshCAM and not in CorelDRAW and your problems will be solved. Don't try to get something to work that isn't the proper way. Work on learning to design and draw your parts in MeshCAM.
    Jermie
    http://www.eartaker.net http://thehorticulture.net

  4. #4
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    If the machined circle was 0.040" when cut, then you have a metric/inch conversion somewhere. It is a 1.0 circle alright, but maybe something is interpreting that as 1.0mm, not 1.0".

  5. #5
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    Hello Guys!

    first of all, MeshCAM V3 creates 3D-G-Code.
    Its possible to mill simple things like a circle, but it creates horrible Runtimes..

    For Ceating 2,5D G-Code, use LazyCAM, Sheetcam or one of these.

    I´m using MeshCAM, it can import STL´s, Jpegs and other graphics, but you cannot draw in MeshCAM..

    For very simple things like circles, rectangles, try the wizards in Mach3.
    They create a G-Code you can run immediatly.

    MeshCAM wants to know the Height and Width of the image, when your Image had Borders , lets say the circle did not fill all the Image, MeshCAM will shrink the circle when you tell MeshCAM to make the width and Height 1". MeshCAM measures all pictures borders, this function is more for artwork.

    Sorry for my bad english, its a long time since Schooltime..

    Greetings from Germany, Tom

  6. #6
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    Quote Originally Posted by RedCoder View Post
    Greetings! I'm a newbie at this, literally my first post so bear with me...

    I have a Sherline mill, I'm not sure what model.
    I got it working in Mach 3.
    I can move the 3 axis's manually and I've figured out how to reset the x, y and z to zero.
    I have figured out how to load a gcode file and make the mill run it.

    I am using CorelDRAW 12 to make basic shapes.
    I've figured out how to use MeshCAM V3 to create a gcode file.

    My question is - How do I make the same size in CorelDRAW when the shape is machined? I ask this question because I made a simple circle in CorelDRAW that was 1 inch by 1 inch.
    I exported to a .png and imported into MeshCAM. I told MeshCAM that the file was 1 inch by 1 inch.

    I ran the gcode produced in Mach3 and the circle was soooooo small! Nowhere close to an inch!


    Does anyone have a Gcode "Ruler" program that I can run through what will correspond to real inches/mm?

    Also, can anyone share with me the software they use to go from Idea to Gcode?

    First, make sure that your motors are tuned correctly. Mach 3 has a calibration function. You can command an axis to move 1 inch. Use a dial indicator { 1" SAE/Metric Digital Indicator } to measure this and adjust the number of steps until correct. Before you address the software issue make sure that this is correct.
    You can see my 11-13-2010 post here: http://www.cnczone.com/forums/bencht...y_running.html

    Hope this helps,

    Iron-Man

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