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Project Cut Undersize

Discussion in 'SketchUcam Bugs' started by BArnold, May 18, 2015.

  1. BArnold

    BArnold Woodworker

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    Over the past couple weeks, I've been spending a lot of time tweaking the calibration of my SO2. I've run some Square-Circle-Triangle cuts using a published drawing and gcode as well as an SCT drawing I made in Easel.

    Being satisfied with the results, I attempted to cut a zero-clearance insert for my table saw that I has drawn in SketchUp 2015. I used SketchUcam to create the toolpaths and all seemed fine - until I ran the project. The result looks like it should, until I measure it. It should be 14.5" long by 4" wide but actually comes out about 14.4" by 3.94" - too small to use.

    To double-check my SO2 calibration, I set up a 14.5" by 4" rectangle in Easel and ran it. The result was 14.5" by 4".

    In all cases cited above, I used the same 1/8" double flute end mill that measures exactly 1/8" with my caliper.

    Ideas?
     
  2. swarfer

    swarfer Moderator Staff Member

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    a tenth of an inch short, right? and 60 thou in the other direction.
    there are a lot of unknowns here so we need to remove some of them. if you can post the sektchup file AND the g-code you generated from it so I can see it, I can check for the issues I know something about, ie , software. I don't know Easel at all, maybe you can post the G-code form that as well so I can compare it.

    the other thing to check is feed speed, and acceleration, and depth of cut. a machine will be able to accelerate much faster when not cutting and might lose steps the moment is starts cutting.
    did you use different feed rates between the 2 bits of software?
    different pass depth?

    then there is a microstepping. more microsteps = less power. more voltage = more power (retaining the same amperage of course, don't want to burn out the motor!)

    I just set up a drawing of a 14.5 by 4 " rectangle and placed an outside cut on it. bit diameter I set to 0.2" to make the mental math easier.
    I placed the bottom left corner of the rectangle 1 inch up and 1 inch right of the origin.

    Here is the code
    %
    (Generated by SketchUcam V1.3a-edc1)
    (Bit diameter: 0.2")
    (Plunge Feed rate: 40.0"/min)
    (Material Thickness: 0.3")
    (Material length: 98.0" X width: 47.0")
    G90 G20 G49 G61 G17
    M3 S30000
    G0 Z0.1000
    X0.9000 Y0.9000
    G1 Z-0.3000 F40
    X15.6000 F80
    Y5.1000
    X0.9000
    Y0.9000
    G0 Z0.1000
    G0 X0 Y0 (home)
    M05
    M30
    %

    so X starts at 0.9 and moves to 15.6
    0.9 + 0.1 (half the bit) is 1 inch, the left edge of the object
    15.6 - 0.1 is 15.5, less the 1 inch on the other end is 14.5, the length of the object
    so the math in the G-code checks out.

    that eliminates that on this end, now I need to see your files to cross check.
     
  3. BArnold

    BArnold Woodworker

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    Here are my files:
     

    Attached Files:

  4. BArnold

    BArnold Woodworker

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    I copied the code you posted, pasted it into Wordpad, and modified it for a 1/8" end mill bit. When I ran the code below, I got a rectangle that is 14.5" long by 4" wide.

    M3 S10000
    G20
    G0 Z0.2000
    X0.9375 Y0.9375
    G1 Z-0.03 F20
    X15.5625 F20
    Y5.0625
    X0.9375
    Y0.9375
    G0 Z0.1000
    G0 X0 Y0 (home)
    M05
    M30
    %
     
  5. BArnold

    BArnold Woodworker

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    As a further test, I set up my table saw insert in Inkscape and imported the SVG into Makercam to make my toolpaths. When I ran it, the insert came out to exactly 14.5" by 4". I attached the gcode for you to compare.
     

    Attached Files:

  6. swarfer

    swarfer Moderator Staff Member

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    hmmm, blue lines everywhere. bluelines are INSIDE cuts, but you have one around the outside.
    do try an outside cut around the outside, garranteed to work better (-:
    outside cuts come out orange, as in the files below.

    for some reason your objects face was reversed (showing white). I removed all the cuts, reversed it so it shows blue (right click the face and select reverse face) and then added the cuts.
     

    Attached Files:

    Last edited: May 20, 2015
  7. BArnold

    BArnold Woodworker

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    Well, color me a bit embarrassed! I see what you mean about the different color lines and I know how I got there. When setting up my drawing, as I chose the Inside or Outside tools they worked opposite of expected. For example, when I chose the Outside tool and moved the cursor to the drawing, the line popped INSIDE the outer perimeter; the Inside tool would place a line on the OUTSIDE of the perimeter. So, seeing a line on the outside of the workpiece, I assumed that's where the cut would happen. In order to get the Outside tool to place a line on the OUTSIDE of the perimeter, I had to press Shift to toggle its position. When I re-worked my drawing, the resultant cut was correct.

    On the comment about the color of the face of the drawing, the correct color of the "show" face in SketchUp is white. I noticed when SUcam produces the outside path, the color of the face changes to blue. Does the color of the face affect how SUcam interprets the drawing?

    Thank you for your help!
     
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  8. swarfer

    swarfer Moderator Staff Member

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    I have no idea why pressing shift to select the opposite side is even allowed (-:
    I have the 'woodworking' theme selected and for me, if I just draw a rectangle the face is pale blue. this is the right way up for inside and outside cuts to work correctly. I think the face color is dependent on the theme selected, so use whatever side of the face gives you the correct cuts, I cannot dictate a color since that will vary with the theme.

    I am not seeing a color change when I add a cutline, though the face between the cutline and the object is white for me.
    hmm, not easily visible in this image >-:
    facecolor.png
     
  9. BArnold

    BArnold Woodworker

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    I'm using the "Woodworking - Inches" template and the "Woodworking" option in "Default Styles".

    You're correct about the visible face of a rectangle being blue when drawn. When it's pulled into a cube, the external faces become white.

    It appears there was a change between v1.2 and v1.3, in that what I described as the action of the outside and inside tools is no longer like that. When I choose the outside tool, it defaults to placing a cut line outside the object. With the inside tool, the default is inside the shape. In both cases, pressing "Shift" toggles the position.
     
  10. swarfer

    swarfer Moderator Staff Member

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    i feel you are missing the crux here. if the face is the correct way up, the outside tool will place an outside cut by default (and inside too an inside cut). if it defaults to a cut on the inside, then your face is reversed and you need to reverse it (to the right way up) before placing cuts on it.
     
  11. 3DMON

    3DMON Moderator Staff Member

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    I think that pressing shift was an old feature from way back when we were transitioning from under slung gantry to overhead gantry and isn't needed and should not be used anymore.
     
  12. TigerPilot

    TigerPilot Well-Known Member

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    If an outside cut shows up inside reversing the face also will make the outside cut be outside.
     
  13. BArnold

    BArnold Woodworker

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    OK - did another test drawing this morning. It had been drilled into me by a certified SketchUp trainer that the working face of an object should be white. So, before I applied the SUcam tools to a flat object, I reversed the face. Or, in one case, I had drawn a 3d version of my object, copied and pasted the top face to the XY plane and it remained white. In any case, now that I know how everything has to work together, I'm good to go!!!

    Thanks, guys!!!
     
  14. 3DMON

    3DMON Moderator Staff Member

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    In 3d white is correct but in 2d blue is the working face.
     

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