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Thread: Losing steps while cutting

  1. #1
    Join Date
    Mar 2004
    Location
    Lenox High School, Lenox MA
    Posts
    818

    Default Losing steps while cutting

    While cutting HDU on a 3D finishing cut I was losing steps. I was using a new Beckwith 1/4" carbide bit. Cut was 1/2" deep with a 10% stepover at 200"/minute. The cut would be fine for quite a while and loose steps causing the cut to be slightly off track.
    Other than cleaning the rack and pinion and applying fresh grease what might remedy the loss of steps. The is a 10 year old 4g Shopbot benchtop. I have recently made cuts that are much more stress on a cut than cutting HDU. I also did a USB port test with the Shopbot utility, the rate was 76.5%.
    The machine has not been used heavily over the 10 years.


    Thanks,

    Phil
    Last edited by phil_o; 03-17-2019 at 05:20 PM.

  2. #2
    Join Date
    Nov 2012
    Location
    Lancashire, UK
    Posts
    62

    Post Safely eject USB device

    Dear Phil

    Early that day (or any time since you turned the desktop on) did you remove the device from the USB port without using the the 'safely remove hardware and eject media' option.

    We have had issues when staff have 'pulled the plug' without safely ejecting. We found that doing a hard reset - shutting down the computer and turning the power off the shopbot, then waiting a short while before turning back on, prevented further problems, as long as the USB was ejected correctly.

    Also is is probably best to use shielded USB leads.

    Sincerely
    Martin

  3. #3
    Join Date
    Mar 2004
    Location
    Lenox High School, Lenox MA
    Posts
    818

    Default

    Martin, this is the first time I've heard of the safely remove hardware and eject media option. How is it done?

    Thanks,

    Phil

  4. #4
    Join Date
    Feb 2010
    Location
    SOUTH CENTRAL COLORADO
    Posts
    1,120

    Default

    my first experience with loosing steps, the brushes on my router needed changing and i was loosing rpms

  5. #5
    Join Date
    Sep 2006
    Location
    Garland Tx
    Posts
    2,221

    Default

    I recently experienced what I thought was loss of Z steps… turned out to be a totally warn out collet!

    SG

  6. #6
    Join Date
    Jan 2011
    Location
    Buchanan Michigan
    Posts
    123

    Default

    Iv had issues with static electricity building up and causing the tool path to jump and act crazy. Not saying that this is you issue but maybe worth looking into. I fixed my static issue by adding a good earth ground to the machine and the vacuum hose.

  7. #7
    Join Date
    Nov 2012
    Location
    Lancashire, UK
    Posts
    62

    Post Safely eject USB device

    Quote Originally Posted by phil_o View Post
    Martin, this is the first time I've heard of the safely remove hardware and eject media option. How is it done?

    Thanks,

    Phil
    Dear Phil

    The example here is off my tablet Windows 8.1; I know it is similar in 7 and there will be the option in 10.

    SafelyRemove.jpg

    All the users in our workshop know to use this to remove the USB memory sticks which we use to transfer part files. Failure to do so has caused some weird events including missed steps, comms errors and worse.

    You will need to do this if you are disconnecting your laptop or tablet from your ShopBot desktop with a USB lead.

    Sincerely and in good faith
    Martin

    PS
    Rob's right - good earthing (you would say grounding) is essential.
    SG is right people don't change collets (and collet nut) as often as they should.
    Last edited by Martin Reid; 03-18-2019 at 01:56 PM. Reason: added PS

  8. #8
    Join Date
    Mar 2013
    Location
    Memphis TN
    Posts
    694

    Default

    I've never used the "safely remove and eject media" option on my SB computer. I just read the files, not write to them. As long as you're not writing to the USB device, the eject operation is optional.
    ShopBot Details:
    PRS Alpha 96x60x12
    4hp Spindle
    12" indexer
    Aspire
    Rhino

  9. #9
    Join Date
    Mar 2004
    Location
    Lenox High School, Lenox MA
    Posts
    818

    Default

    Thanks to all. I learned a lot. Not sure exactly what the problem is but I have things to look for; hot stepper motors, feed rate too high, static.
    I also contacted Shopbot support and performed a few maintenance items. These links are worth a look for anyone with a CNC.
    Maintenance items http://www.shopbottools.com/ShopBotDocs ... 0%2024.pdf
    Computer issues https://www.youtube.com/playlist?list=P ... aY2HkQMJtj
    Tips on setting up your PC https://mail.google.com/mail/u/0/#inbox ... rojector=1
    I spent most of the morning checking out a number of maintenance issues. Now I hope all is good.

    Thanks again,

    Phil

  10. #10
    Join Date
    Mar 2004
    Location
    Lenox High School, Lenox MA
    Posts
    818

    Default

    On the Vectric forum Gary Campbell suggester that the stepper motor running for hours can build up enough heat to cause the loss of steps. I set up the file to cut as a 3D raster finishing toolpath, running left to right. So the X axis stepper motor was doing most of the work. I was loosing steps in the X axis. I'm considering setting up the file either as a raster on a 45 degree angle or an offset toolpath. Any suggestions.

    Thanks,

    Phil

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