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Thread: Offsets while running, but jogs home correctly

  1. #1
    Join Date
    Mar 2006
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    Habitat For Bats, Jackson GA
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    Default Offsets while running, but jogs home correctly

    PRT Alpha 7.2 circa 2006
    New control board, USB and some relays a couple of years ago, running 3.8.42

    A couple of years ago I had several occurrences of this behavior and never discovered the reason for it. What I did do was put in a newer control board so I could run the newer software, replaced some sticking relays and put in a new USB everything and replaced the control PC. I thought the problem solved and it was for 2 years.

    Then, yesterday it did it again, about 1/3 of the way through a file that has literally been run more than 1000 times without changes the cutting OFFSET in the middle of the run, finished cutting with the offset (sort of like it lost 0,0) but then jogged home to 0,0 on the dot and the next run it was fine.

    WHY? Why is it offsetting in the middle of the file and finishing while maintaining the offset? It picked up after finishing a cut in the right place, jogged to the next start point getting it wrong but continuing the cut perfectly with the offset until it finally reached a limit switch at the far end of the table and stopped. I jogged home expecting it to land off target of 0,0 but it hit it perfectly. The next sheet ran fine but I keep waiting for it to waste the next $50 sheet of material.

    Ideas?
    Last edited by harryball; 02-21-2018 at 10:46 AM. Reason: typo, info fix.

  2. #2
    Join Date
    Jan 2004
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    iBILD Solutions - Southern NJ
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    7,763

    Default

    Hey dude - nice to hear from you - sorry it is because the tool is messing up.

    Sounds to me like your table base coordinates are jacked up. Try resetting them with the ZT command. Move your tool to physical 0,0 and do a ZT.

    See if that fixes it...let us know.

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

  3. #3
    Join Date
    Mar 2006
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    Habitat For Bats, Jackson GA
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    Default

    Quote Originally Posted by Brady Watson View Post
    Hey dude - nice to hear from you - sorry it is because the tool is messing up.

    Sounds to me like your table base coordinates are jacked up. Try resetting them with the ZT command. Move your tool to physical 0,0 and do a ZT.

    See if that fixes it...let us know.

    -B
    I did the ZT for good measure on the physical table again in case it lost it. What confuses me is it STARTS cutting correctly then without warning somewhere in the file it offsets and just keeps cutting. When it finishes and does a JH, it no longer has an offset but returns to true home.

    Anyway, it happened once so far, ran another 10 sheets with no problems. I just hate things that are not consistent. Run the same file, you should always get the same result.

    On another note, I'm always around lurking, just less to say these days as we are busy. I never would have believed I'd build so many bat houses in my life and this year... even more. We now have State contracts, provide complete packages with brackets (had to learn to mig weld and plasma cut) and most of our weekends are spent doing Bat House workshops in the Spring Summer and Fall. We did our first Winter Bat House workshop in Athens this January.

    Bot is still running after 12 years and It now has hardened rails on every axis including the new Z I put on last December.

  4. #4
    Join Date
    Jan 2004
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    iBILD Solutions - Southern NJ
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    Default

    Robert - I don't know. Sometimes things just get whacked out - sunspots? Gremlins?

    I was going to suggest that maybe your file got corrupted from a disk fragment or something - but if it's running good now, that blows that theory out.

    Glad things are going well for you!

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

  5. #5
    Join Date
    Nov 2012
    Location
    Lancashire, UK
    Posts
    43

    Default Comms Error

    Dear Harry

    Is the file you are running on the hard drive or on a memory stick? Is there anyone plugging and unplugging memory sticks?

    On the 'thankfully' few occasions when this unpredictable behaviour happened here, once it was out of the cut and set of at a warp speed and hit the limit switch the next time (over a year later) it didn't pull up and set off for the limit switch with the 19mm cutter in the work piece - set fire to the piece. As with you we couldn't be sure what it was but I'm convinced it was one of the lads unplugging memory sticks without going through the 'safely remove hardware' routine. This would unsually generate a 'Comms Error' but on these occasions it just 'repositioned' itself.

    Anyway I'm watching with interest to see what others might say.

    Sincerely and in good faith
    Martin Reid

  6. #6
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    Quote Originally Posted by Martin Reid View Post
    Dear Harry

    Is the file you are running on the hard drive or on a memory stick? Is there anyone plugging and unplugging memory sticks?

    On the 'thankfully' few occasions when this unpredictable behaviour happened here, once it was out of the cut and set of at a warp speed and hit the limit switch the next time (over a year later) it didn't pull up and set off for the limit switch with the 19mm cutter in the work piece - set fire to the piece. As with you we couldn't be sure what it was but I'm convinced it was one of the lads unplugging memory sticks without going through the 'safely remove hardware' routine. This would unsually generate a 'Comms Error' but on these occasions it just 'repositioned' itself.

    Anyway I'm watching with interest to see what others might say.

    Sincerely and in good faith
    Martin Reid
    My son was running it at the time but he also knows never to insert/remove a USB stick while a file is running. I have an SSD drive in the notebook, this configuration has been running trouble free 2+ years without changes. There is no internet connection, all is disabled and services have been slimmed down to the bare minimum. We did swap the vac pump out, but that was 6 months ago now so I don't think we have a grounding problem.

    We ran out of material yesterday, (amazing how fast we go through a full unit of ply now) truck is inbound so we should be cutting again before the end of today. Still, it has not happened again.

  7. #7
    Join Date
    Oct 2000
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    Willis Wharf, VA
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    1,596

    Default

    Hey Robert,

    With any luck it was just an anomaly and won't happen again, but there have been occasional tools that would miss-time the transition between moves and jogs and would not apply the multiplier correctly so moved an incorrect distance during a cut. A setting was added to the bottom of the VU settings in the ShopBot control software a couple of versions ago that let you turn off that "gear shift". It will slow down your jogs a bit so that you won't be able to jog at 30 in/sec, but if it happens again you might try turning that off.

    Bill

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