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Thread: Z-Depth Trouble

  1. #11
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    Sep 2015
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    Buford, GA
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    I tried to use my Micrometer to measure the Z travel. With the imperfect method of measurement it seems to be accurate in terms of the stepper values. It certainly does not explain the pattern from the above picture.

  2. #12
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    Dec 2008
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    Attached Images Attached Images
    Kenneth

  3. #13
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    If it is consistant about cutting on the edge and not in the center like your last picture, the spoilboard moving has to be the issue.
    Kenneth

  4. #14
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    Sep 2015
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    Buford, GA
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    Thanks for the pic. I've verified with Vectric that the post processor they have for V-Carve PRO is, in fact, the correct one for the ATC. It has all the proper call-outs for the ATC. Anyway, none of that explains the specific depth problems I'm experiencing I don't think.

  5. #15
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    Sep 2015
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    Buford, GA
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    Thanks Ken. Yea, that start depth is always zero for me.

  6. #16
    Join Date
    Dec 2008
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    Diamond Lake, WA
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    How stable is your plenum? I've heard of plenums flexing when the vacuum is on. As far as the spoilboard, as long as the plenum is stable and can't move, once you surface the spoilboard, it should be perfectly aligned with the CNC. Since 2009 I've not had a problem with my spoilboard moving. But being in GA, I suspect humidity could be a problem over time causing an MDF spoilboard to swell and shrink.

    Is your Z-assist cylinder working properly? The ATC spindle is a WHOLE LOT heavier then the smaller spindles. The Z-assist (pneumatic) helps the Z motor handle this extra weight. I had that issue when I first setup my ATC. Once I got the Z-assist cylinder securely attached a lot of problems seemed to fade away.

    Are you using the pressure plate for ZZero or the aluminum bar? I found the pressure plate can be a little off. I use the pressure plate for my CN72 routine but not for zeroing on the spoilboard or top of material. I have a pressure plate for Zzeroing on the spoilboard and material but I found it to not be accurate enough. Good old C2 on the aluminum plate seems to be the best.

    The pressure plate enables you to Zzero without the alligator clip being attached to the bit. Since the ATC spindle has ceramic bearings, you need the alligator clip or the pressure plate. On my 2.2hp spindle I never had to use an alligator clip on the bit.
    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.

  7. #17
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    Sep 2015
    Location
    Buford, GA
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    I have the pressure plate on the ATC, but I use the Z-Zero plate on the table.

    I am leaning towards a plenum problem. I just re-zeroed to the table and ran this pattern on the blank table with the vacuum on.

    Flat Table Test.jpg

    This was the result, both on a piece of 1/8" hardboard AND on the table itself. The odd part is that where it does not touch the table is exactly where I zeroed it.

    From X 0.jpg

    From X 96.jpg

  8. #18
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    Mar 2013
    Location
    Memphis TN
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    One possible way to test if the plenum is at fault:

    1. Cover a zone with thin plastic.
    2. Place a piece of paper in the center of the zone.
    3. Zero an end mill to that piece of paper so that the paper slides with resistance.
    4. Turn on the vacuum.
    5. Check to see if the gap between the end mill and the piece of paper has changed.
    ShopBot Details:
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  9. #19
    Join Date
    Aug 2011
    Location
    Wilkesboro, NC
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    My bet is that when you are flattening your table, the vacuum does not have as much downforce on the open table as it does when it is covered with masonite. So the middle section is sitting higher when it is being surfaced and then pulled down when nearly sealed with the top sheet. Do you have a gauge on the table side of your vacuum? I'm not sure if mine measures psi or inches of mercury, but my table only draws 2-3 when it is just the spoilboard, but I can get it upwards of 15 when I have it completely covered with material. Also sealing the edges of my table made a big difference

  10. #20
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    Oct 2000
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    Willis Wharf, VA
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    Have you tried pushing down on the table when the vacuum is off, to see if the layers are not bonded together and there's some spring in the lamination?

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