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Thread: cutter veering off circle

  1. #11
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,986

    Default

    Hook yourself up with this: Windows Image Resizer Powertoy, then right click on pics you want to post, choose 'Resize Pictures' and pick medium or large. THEN post your resized pic(s). The problem is the pic you attached is illegible and it is most likely because it was very large on disk when you uploaded it...Resized pics will appear larger than what you posted. I can't read a thing you wrote in VCP.

    The problem with your machine is that you're probably machining too quickly with not enough RPM. When cutting a circle, there are a number of direction changes going on between the X & Y axes. Combined with a ramped step down, you could be right at the point where the machine needs more torque to follow through on the projected path, than is available.

    Stepper motors are rated at holding torque. They have their most torque at 0 RPM. The faster you go, the less torque they have. The motors you have on your machine start to really fall off in the torque department at 3 IPS/180IPM. You need to account for this when cutting dense materials. Pull the move speed down, increase RPM & reduce step down/pass depth until you've lightened the cut enough not to lose position.

    When cutting new or questionable materials, start slow. Set MS to 60 IPM and feather the speed up gradually. Look, listen and figure out where the machine is happiest. Corian isn't going to cut cleanly at high speeds on a Standard machine. You'll run out of RPM for proper chipload if using a single flute Spiral-O beyond 90 IPM. You say the issue also happens in 'wood' - not very specific...Solid maple has to be machined somewhere in the 60-120 range and softer woods can go faster if you have the RPM for a clean cut.

    -B
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    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  2. #12
    Join Date
    Jan 2004
    Location
    Marietta GA
    Posts
    486

    Default

    Quote Originally Posted by Brady Watson View Post
    Hook yourself up with this: Windows Image Resizer Powertoy, then right click on pics you want to post, choose 'Resize Pictures' and pick medium or large. THEN post your resized pic(s). The problem is the pic you attached is illegible and it is most likely because it was very large on disk when you uploaded it...Resized pics will appear larger than what you posted. I can't read a thing you wrote in VCP.

    The problem with your machine is that you're probably machining too quickly with not enough RPM. When cutting a circle, there are a number of direction changes going on between the X & Y axes. Combined with a ramped step down, you could be right at the point where the machine needs more torque to follow through on the projected path, than is available.

    Stepper motors are rated at holding torque. They have their most torque at 0 RPM. The faster you go, the less torque they have. The motors you have on your machine start to really fall off in the torque department at 3 IPS/180IPM. You need to account for this when cutting dense materials. Pull the move speed down, increase RPM & reduce step down/pass depth until you've lightened the cut enough not to lose position.

    When cutting new or questionable materials, start slow. Set MS to 60 IPM and feather the speed up gradually. Look, listen and figure out where the machine is happiest. Corian isn't going to cut cleanly at high speeds on a Standard machine. You'll run out of RPM for proper chipload if using a single flute Spiral-O beyond 90 IPM. You say the issue also happens in 'wood' - not very specific...Solid maple has to be machined somewhere in the 60-120 range and softer woods can go faster if you have the RPM for a clean cut.

    -B
    i have an older PRT with a 4g controller. I never cut anything but foam at 3ips.

  3. #13
    Join Date
    May 2006
    Location
    , SW PA
    Posts
    220

    Default

    Thank you everyone. I just thought that with the RBK control box, the newest motors, the hardened rails and the retro z I could push it a little faster, guess not.

    Bob

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