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Thread: what happened here

  1. #1
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    Default what happened here

    Things were going well when this happened. Z went crazy in the middle of a cut. The picture shows how things were great, then all of a sudden it went to trash. Any help out there.
    Thank you, Graham
    Attached Images Attached Images

  2. #2
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    Graham…

    It looks similar to an issue I had when the down blast of warm air from my router dried out the damper interior of the board during a very long (timewise) cut. The solution, for me, was to re zero the Z axis a few thousandths lower after completing the cut and running it again.

    SG

  3. #3
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    Thank you Steve. I was afraid the machine lost Z midway through the cut. 5 hour cut.
    Graham

  4. #4
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    Apr 1999
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    Rock Hill SC
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    Quote Originally Posted by Grahamd View Post
    Thank you Steve. I was afraid the machine lost Z midway through the cut. 5 hour cut.
    Graham
    It appears that your Z went a little deeper and then corrected itself. If it had just lost, or gained, steps I would expect it to be uniform once it went wrong.

    Loose pinion? Worn pinion? Rack need cleaned and lubricated? Static? Noisy cable connection?

  5. #5
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    Collett slipping? I've had that happen a few times. A dirty collett can cause all kinds of problems. I clean colletts thoroughly after each bit change.
    Don
    Diamond Lake Custom Woodworks, LLC
    www.dlwoodworks.com
    ***********************************
    Life is not a journey to the grave with the intention of arriving safely in one pretty and well preserved piece; But to skid in broadside, thoroughly used up, worn out, bank accounts empty, credit cards maxed out, defiantly shouting "Geronimo"!

    If you make something idiot proof, all they do is create a better idiot.

  6. #6
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    ny
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    I am leaning towards steve g's answer, as the cut is made stresses change and the wood moves. I have that happen a lot with my wooden signs. I would do a roughing pass with a large bit and go to finish it will save a lot of time too.

  7. #7
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    Dec 2000
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    Thorp, WI
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    Wood movement from stress and humidity....not on a 3D finish pass. You'd have to stop the machine and wait between each pass to make it show that much variation. Did your holddown become slightly loose? You don't say what type/model of machine you're using, but if it is rack and pinion, check the grub screws on the Z axis. Make sure they're seated and tight and that the pinion is firmly seated into the rack. Check for any play in the Z and Y cars. Debris under a V roller on the axis that is rastering. Loss of steps in both directions as it jerks the Z up and then back down. If you have a standard SB, this is quite possible if you don't run proper ramping and feedrates.

    Spindle or router? If router, a bearing going bad might be possible.

    5 hours!? How big is this? A model like that, depending on the size, shouldn't take anywhere near that long. If it's in the range of 4x6 or 6x8, you should be able to knock that out in no more than 1 to 2 hours (with 8% - 10% stepover). Again, ramps and feedrates apply here as well. Read up on it here.

    "He who would trade liberty for some temporary security, deserves neither liberty nor security" - Benjamin Franklin
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  8. #8
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    Jun 2017
    Location
    Lewisville, NC
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    Thanks to all. Have been away for a few days. I am running a Buddy 32. It does have a spindle installed at the factory. Bought a computer just for the machine that is never allowed access to the outside world. The roughing pass is a good idea. 5.5 hours is a long time. I will check all the above mentioned areas.
    Thanks again, Graham

  9. #9
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    Jun 2017
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    Lewisville, NC
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    The oval is 4.75by9.75. Bit is tapered 1/32 ball end carving bit. This is all new to me, so the learning curve continues.
    Thanks, Graham

  10. #10
    Join Date
    Jun 2017
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    Lewisville, NC
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    Quote Originally Posted by srwtlc View Post
    Wood movement from stress and humidity....not on a 3D finish pass. You'd have to stop the machine and wait between each pass to make it show that much variation. Did your holddown become slightly loose? You don't say what type/model of machine you're using, but if it is rack and pinion, check the grub screws on the Z axis. Make sure they're seated and tight and that the pinion is firmly seated into the rack. Check for any play in the Z and Y cars. Debris under a V roller on the axis that is rastering. Loss of steps in both directions as it jerks the Z up and then back down. If you have a standard SB, this is quite possible if you don't run proper ramping and feedrates.

    Spindle or router? If router, a bearing going bad might be possible.

    5 hours!? How big is this? A model like that, depending on the size, shouldn't take anywhere near that long. If it's in the range of 4x6 or 6x8, you should be able to knock that out in no more than 1 to 2 hours (with 8% - 10% stepover). Again, ramps and feedrates apply here as well. Read up on it here.
    Brady's article was great. Thanks. I have used him for a scan in the past.
    Graham

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