Welcome to Our Community

Some features disabled for guests. Register Today.

cam.openbuilds.com bug in generating tool path for arcs

Discussion in 'OpenBuilds Bug Report' started by Dugi, Oct 7, 2021.

  1. Dugi

    Dugi New
    Builder

    Joined:
    Mar 5, 2019
    Messages:
    2
    Likes Received:
    1
    Hi,
    I was trying to generate gcode for CNC router to cut simple shape with straight lines and arcs.
    I was draw shape in LibreCAD, export to SVG, checked it in Inkscape, and imported in CAM.
    (Why I didn't use DXF? cam.openbuilds.com have serious problems with importing DXF generated by LibreCAD.)
    Shape imported in CAM appears correctly. I added CNC: Vector, no offset.
    Problem is that CAM mills arcs from beginning to end, and after that tool is going from end to beginning in straight way (diagonal), without lifting the tool. This "no lifting the tool" is the bug.

    I include SVG file and GCODE generated by CAM.

    Thank You and best regards! :)
     

    Attached Files:

  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    8,401
    Likes Received:
    2,768
    I use QCAD and LibreCAD extensively myself. Explode all non polyline entities into Polylines, then save as DXF R14. See docs:software:file-errors [OpenBuilds Documentation]

    We only support closed vectors. Having a missing side, we'll add one to make it a closed vector.

    Give it proper closed polylines. This may entail converting objects to polylines / svg paths first and making sure its all joined up into continuous polylines/paths as needed
     
    Dugi likes this.
  3. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    8,401
    Likes Received:
    2,768
    Checking our your actual file:

    By-eye it should contain "2 paths" - the outside profile and the inside cut. But in the document tree we can see a lot of "paths" - because it hasn't been joined correctly - you have a tonne of short little segments but they aren't part of the "whole" as it should be. Highlighted a couple segments for you on the 3D view too, easy to see its seperate as you hover over them though.

    Each of those segments should have all been joined together into one long PATH (or Polyline for DXF) - as its its not a cut friendly file and most CAMs would bork on it. Putting in clean data avoids forcing the CAM to try to figure out what you want.

    In this case, I'd select the segments that form the outside, and Union them together first. Then seperately select the 4 straight segments and Union them to create a rectangular polyline/path. Thus ending up with just two polylines/paths as was you intention when you were designing it after all.

    upload_2021-10-7_13-29-52.png
     

    Attached Files:

    Dugi likes this.
  4. Dugi

    Dugi New
    Builder

    Joined:
    Mar 5, 2019
    Messages:
    2
    Likes Received:
    1
    Thank You for all your effort and explanations :).
    I checked "create a plyline from existing segments" in FreeCAD, and that do the job! CAM imports my DXF with no problems, and I can create cut inside or outside path.

    BTW. I observed that CAM can't use POINT from DXF. It would be userfull to create drilling job.

    Thank You, You helped me a lot! :)
     
    Peter Van Der Walt likes this.
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    8,401
    Likes Received:
    2,768
    Drawn your holes as circle-polylines (easier on the eyes to see the right size of hole in the drawing, known what bit to use etc) then use the Drilling operation in CAM. It finds the center of the selected entity and does n proper drill job :)
     
    Dugi and David the swarfer like this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice