Welcome to Our Community

Some features disabled for guests. Register Today.

Machine cutting 1mm too big

Discussion in 'CNC Mills/Routers' started by Ats101, Apr 8, 2024.

  1. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    Hello all,

    I am in the middle of a project and decided to cut some spacers to aid with the project.

    Because the spacer key needs to be accurate to be of use, I was keen to measure it. The length and width of the spacer I designed on Vcarve is a rectangle measuring 20 x 30 mm.

    The actual cut piece is measuring approx 21mm x 30.8 - measured with Vernier callipers.

    I am working with the Ooznest Workbee 1500x1500.

    I have checked the 1/8 bit and the diameter is consistent with this.

    After the first cut of spacers, I went to check for slack in the axis. There was some in the x axis which I completely minimised when I adjusted the nut block.

    The cut after that was minimally better as quoted above.

    What do you guys think?

    TIA.
     
  2. Peter Van Der Walt

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

    Joined:
    Mar 1, 2017
    Messages:
    14,263
    Likes Received:
    4,167
    Wizards and tools > Calibration to fine tune your steps per mm - provided its mechanically tight, true and trammed.
     
  3. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    Thank you - doing it now!
     
  4. Peter Van Der Walt

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

    Joined:
    Mar 1, 2017
    Messages:
    14,263
    Likes Received:
    4,167
    Use the longest distance possible (100mm default is just entered by default for folks with small machines like our Minimill)
     
  5. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    I presume the maximum size would be limited by Vernier callipers limit of 150mm?
     
  6. Peter Van Der Walt

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

    Joined:
    Mar 1, 2017
    Messages:
    14,263
    Likes Received:
    4,167
  7. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    Ok took your advice.

    I cut some 1200mm lengths this morning. On measuring it just now - they measure between 1198 and 1199mm.

    I just cut out a 50x50 square and measures 50.8 and 50.7mm.

    This cannot be steps related right?

    My machine may not be square?
     
  8. Peter Van Der Walt

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

    Joined:
    Mar 1, 2017
    Messages:
    14,263
    Likes Received:
    4,167
  9. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    I cut the 1200mm length at the front of my machine.

    I cut the 50x50mm square on some scrap which was situated at front middle of my machine.

    I don't see how being slightly out of square could give this inconsistency of acutal cut being larger at 50mm but smaller at 1200mm.

    I'm puzzled??
     
  10. Peter Van Der Walt

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

    Joined:
    Mar 1, 2017
    Messages:
    14,263
    Likes Received:
    4,167
    Well, then it might be backlash. Hold endmill and give it a firm wiggle - unwanted play will show up as a feeling (sense of touch is orders of magnitude more sensitive than sense of sight) follow the feeling of free play to find the source

    Measure squareness by checking the corner a square cut with a Square.
     
  11. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    Machine is square.

    Very minimal play when moving end mill side to side and back and forth. No play as such rather just a slight bit of flex.
     
  12. Peter Van Der Walt

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

    Joined:
    Mar 1, 2017
    Messages:
    14,263
    Likes Received:
    4,167
    Cut recipe aggresive enough to induce deflection?
     
  13. Ats101

    Ats101 New
    Builder

    Joined:
    Jan 28, 2024
    Messages:
    24
    Likes Received:
    2
    its a good thought that crossed my mind. I am using the present settings on vcarve pro. I will reduce feed rate and see what we are left with.

    Thanks.
     
    Peter Van Der Walt likes this.
  14. David the swarfer

    David the swarfer OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Aug 6, 2013
    Messages:
    3,303
    Likes Received:
    1,847
    bit are never the stated diameter. that is why very expensive tool measuring devices are used in industry to measure every tool before it is used.

    checked how? the only good way is with a micrometer. vernier calipers are universally known as 'guessometers' (-:
     

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