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  1. #11
    This was after 1000 moves left then 1000 moves right and the same on the other axis.

    so 4000 moves in total.

    The indent was put at G54 0,0 before I ran the code.

    Guessing it would be visibly out if I had the rising edge set wrong.Click image for larger version. 

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    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  2. #12
    Well, that is pretty much what you are doing so you can say you are not losing steps. However, if you search the forum Jonathan posted an Excel file that will produce G-code to run the machine around then return to Zero.

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  4. #13
    Quote Originally Posted by Desertboy View Post
    In the manual there's "Level of Axis pulse signal" what does this mean? Is that the rising/falling edge?
    Attachment 27697
    This will be the pulse timing and I wouldn't mess with it if your not missing steps or losing position.

    The fact your parts are the wrong size will be down to either a mechanical issue or simply because the pitch doesn't correspond to the steps per setting. The best way is to command a move and accurately measure the distance it moved. And when I say accurately then a tape measure or even a steel rule isn't accurate enough. For instance, I use linear scales with a DRO to compare actual distanced moved to the commanded. I then adjust the steps per until they match.

    The longer the move the better but if you have lets say 150mm length set of digital vernier gauges these can get you very close to perfect.

    Edit: One other thing, if these are cheap Chinese screws the pitch can vary along it's length so it's worth taking readings in a few places. Likewise, if you have been using the machine already and cutting in the same spot all the time then there will be wear in this location compared to the unused or less used regions. This is why it's a good idea to move around the bed when cutting small parts rather always at the easiest place to reach.1
    Last edited by JAZZCNC; 01-04-2020 at 05:22 PM.

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  6. #14
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 10 Hours Ago Has been a member for 6-7 years. Has a total post count of 805. Received thanks 129 times, giving thanks to others 34 times. Referred 1 members to the community.
    Random thought and I'd appreciate anyone else explaining if I'm talking balls, If you home to 0,0 and manually drop the Z into a sacrificial board, raise Z, traverse e.g. G0X33 (you mentioned a 33mm circle), the drop the Z into the sacrificial board (spindle running of course) then the distance between the left edge of the hole created by the first drop and the second drop should be 33mm. If it is, then your scaling is correct. If not then either thread pitch or steps. If it is still 33mm, and you have all the evidence of no loss of steps then I'd seriously be looking at your CAM, tool sizes and compensation.

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  8. #15
    The fact you are cutting circles makes me wonder about the I & J moves, settings for those in the controller (if any), and anything associated with going around corners ?

    This is a bit of a long shot but does it do the same thing if cutting out 33 mm square holes (ignoring the tool rad in the corners) ?

    I just remember something years ago on I & J radius settings (note: this was in Mach3).

    Another option: Is there is a setting for "Maintain velocity (and approximate toolpath)" OR "slow down and follow it exactly" - might be a factor ?

    Sorry, just some straws to clutch at.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

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  10. #16
    I cut 11 indents they are all out by the same amount ~1mm but the distance between the indents is correct.

    Click image for larger version. 

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    So the indent is 49mm and the distance between indents is 51mm. They should be 50mm each.

    Over the 11 indents the distance is correct.

    Set up 1/2" end mill (Brand new trend bit), pocket no stock to leave.

    The top row the clamps weren't tight enough and slipped so cut the bottom row but properly clamped.

    I looked through the DDCSV's settings and every tool offset was set to 0.0
    Last edited by Desertboy; 03-04-2020 at 11:15 AM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  11. #17
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 10 Hours Ago Has been a member for 6-7 years. Has a total post count of 805. Received thanks 129 times, giving thanks to others 34 times. Referred 1 members to the community.
    ...so the errors are not incremental - so I interpret that as the motor steps, scaling etc are all correct

    "Indent is 49mm and the distance between indents is 51mm. They should be 50mm each" - I interpret that that the pockets are undersized?

    Post your Gcode output from Fusion. At least for the first two pockets.

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  13. #18
    Did you measure the tool.?

  14. #19
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 10 Hours Ago Has been a member for 6-7 years. Has a total post count of 805. Received thanks 129 times, giving thanks to others 34 times. Referred 1 members to the community.
    Whoa, random thought - Fusion defaults a number of CAM operations to a roughing cut leaving... 0.5mm for a finishing pass. Have you accounted for this?
    Last edited by Doddy; 03-04-2020 at 11:55 AM. Reason: replaced "functions" with "operations" for consistency

  15. #20
    Quote Originally Posted by Doddy View Post
    ...so the errors are not incremental - so I interpret that as the motor steps, scaling etc are all correct

    "Indent is 49mm and the distance between indents is 51mm. They should be 50mm each" - I interpret that that the pockets are undersized?

    Post your Gcode output from Fusion. At least for the first two pockets.
    Pockets are undersized, here's the code for 1 pocket 50mm in Fusion 360 I had to rename it to .nc to upload from .tap.

    my controller is steps per mm

    Microsteps are 8, 1610 ballscrew

    8*200/10== 160

    I have 1605 on Z so 320

    1:1 direct coupling.
    Attached Files Attached Files
    Last edited by Desertboy; 03-04-2020 at 12:17 PM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

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