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Using the centerline tool

Discussion in 'OpenBuilds Forum Help' started by jbell, Jul 11, 2019.

  1. jbell

    jbell New
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    I'm using the centerline tool to cut a slot with a partial curve. The bit will enter the wood then retract then enter and start cutting. The cut is goes in the opposite direction to the outside tool.

    Is this normal for the centerline cutting or have I done something wrong?
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    What application are you using, screenshots, etc any additional details to help understand the issue :)
     
  3. jbell

    jbell New
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    Hi

    I'm using sketchup cnc file with open builds black box
     

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  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Post the sketchup with Sketchucam file
    Post the gcode file too please
     
  5. jbell

    jbell New
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    Is this enough, don't know how to download the full gcode.

    Thanks
     

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  6. sharmstr

    sharmstr Master
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    The gcode file (according to your screen shots) is in D:\cnc violin file directory. Its only a text file so just attach it here. If it wont accept .nc files (i cant remember) change the extension to .txt.
     
  7. jbell

    jbell New
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    Not having any luck finding D:\cnc violin file directory. I only have C:/
    Did a search but it couldn't find it.
     
  8. sharmstr

    sharmstr Master
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  9. Alex Chambers

    Alex Chambers Master
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    Try searching for bisiach bottom plate channel cut.nc
    Alex.
     
  10. jbell

    jbell New
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    I think this is it.
     

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  11. jbell

    jbell New
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    I was ale to get this from the sketchucan file
     

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  12. David the swarfer

    David the swarfer OpenBuilds Team
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    John please post the Sketchup file. If you dont want it public then send it to me in a private conversation.
     
  13. jbell

    jbell New
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    Hi Dave
    I did a test with only a 6" line at 50% using centerline and it worked correctly. On this project I've done a similar cut with a smaller slot and still does the double dive.

    Thanks
     

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  14. David the swarfer

    David the swarfer OpenBuilds Team
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    John I can fix the Sketchup file but I cannot fix pictures of it (-:
    The reason it is happening is because Sketchup has stuffed up the order of the lines, which can be fixed with one of the plugins on one of my 3 machines. Once I have the sketchup file I will track it down and use it and then tell you how to do it.
     
  15. jbell

    jbell New
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    Thanks Dave
     

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  16. David the swarfer

    David the swarfer OpenBuilds Team
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    the SKETCHUP file (.skp), not the Gcode file (.cnc)
     
    Peter Van Der Walt likes this.
  17. jbell

    jbell New
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    Here its at last.
     

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  18. David the swarfer

    David the swarfer OpenBuilds Team
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    here is one of the little random lines on the left side.
    upload_2019-7-15_10-1-14.png
     
  19. David the swarfer

    David the swarfer OpenBuilds Team
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    on the right side there is this tiny line that needs to be deleted (highlighted blue)
    upload_2019-7-15_10-13-36.png
    in fact there are couple of other little lines around the drawing. find them and delete them.
     
    #19 David the swarfer, Jul 15, 2019
    Last edited: Jul 15, 2019
  20. David the swarfer

    David the swarfer OpenBuilds Team
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    @jbell
    So, having removed those little random lines we can focus on the long lines.
    The issue is that every line segment has a direction and Sketchup can do weird things with chains of line segments. Somehow it does get outlines of shapes correct, so when you add an outside or inside cut it works correctly.

    But, when you do anything to a chain of lines (any edit/move/copy operation) it may rsult on one or more segments being reversed, ie if you have 2 segments AB and CD
    A-----BC-----D
    when the coordinates of B and C are equal, that is a nice curve that can cut as one movement.
    But an edit can cause Sketchup to change the order of the end points
    A----BD----C
    so it looks good on the screen but when the code is moving through the segments is finds A is the beginning of a line, and D is the begining of another line and ignores the fact that B and D are the same point. and this causes the centerline cut to do some segments, or even sequences of segments, 'backwards'. (Yes the sketchUcam code does contain fixes for this and it finds most of them but Sketchup has some creative ways to mess it up that cannot be detected during Gcode generation, sigh!)

    So, the fix....
    You need this plugin
    SketchUp Plugins | PluginStore | SketchUcation

    Once you have that installed you can do this....
    1. triple click the end of a centerline to select all connected segments
    2. select the SketchUcam delete tool [PB]
    3. click the selection. the green highlight will be removed leaving just black lines.
    4. triple click the line again
    5. right click the selection
    6. select the "BZ - Convert to | Polyline" tool upload_2019-7-15_11-4-42.png now that is one contiguous sequence of lines.
    7. re-apply the centerline cut and you should see in Gplot that the cuts are one continuous cut at each depth, from end to end.
    upload_2019-7-15_11-7-31.png
    (yes I know I have the depths wrong...)

    about cutting to specific depths like this.... sometimes I find it easier to set all the centerlines to 100% deep.
    Then I set the 'material thickness' to the actual depth I want, select the lines to cut, and generate Gcode.
    Repeat for all depths that you need.
    Now I can run the depth files separately or I can use the joiner tool to join them together to cut as one job.

    The downside to this is that you may have to do it all over again if something needs to change AND you need to remember what depths to use. I use the label tool to insert reminders for myself (-: (and groups with names stating the depth of cut) I recently did a drawing like this for a tool tray with 4 different depths. Maybe I should do a video about this?
     
  21. jbell

    jbell New
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    Hi Dave

    Thank you very much for your help. It worked great. Not only that but now I have a lot more drawing tools that I didn't know were available.

    Take care and "God seen jou".
     

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