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Thread: Z-Depth Trouble

  1. #1
    Join Date
    Sep 2015
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    Buford, GA
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    Default Z-Depth Trouble

    I'm refining my last post a bit.

    My machine is consistently NOT cutting through the material when it should.

    My machine is a 2016 PRS Alpha ATC. I have skimmed the spoilboard. I program the file to cut through the material by 0.15". That doesn't come close. I keep changing it until I'm telling it to cut into the spoilboard by 0.080" before it does. And it's NOT cutting 0.080" into the spoilboard.

    On my ancient 2001-2002 PRT machine, it worked like a dream, even if I didn't skim the board for weeks.

    What on Earth could be causing this?

  2. #2
    Join Date
    Mar 2013
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    Memphis TN
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    Default

    I don't have an ATC so I can't answer for sure...

    Did you adjust your zero plate when you skimmed the table? Do the end mills in your ATC carousel have to be re-zeroed?
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  3. #3
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    Sep 2015
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    Buford, GA
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    Default

    Yes, I ran the C73 table offset for the zero plate after skimming, and all the bits have been zeroed correctly.

  4. #4
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    Dec 2000
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    Thorp, WI
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    Default

    Does the Z axis actually move the commanded distance? Zero it out, move 1" and use a dial indicator to verify. Try 2", etc. If it's off, your unit values may be incorrect for the Z axis.
    Scott




  5. #5
    Join Date
    Dec 2008
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    Default

    After verifying that it is setting the z height to the correct position, run a file and then check again after the file runs to see if it moved. Bits can slip in a collet sometimes as well. Mainly like was said above, verify it is actually placing the bit at a certain height when you tell it to go there. I have seen loose spoilboards that were flycut without vac hold running and then when a sheet of material is there to cut the vac pulls it down lower. Make sure your cutting file does not have a start depth in vectric. (the box above the desired cutting depth)
    Kenneth

  6. #6
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    Dec 2008
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    Default

    Have you run the C72 on all your tools since you set up? Tis is vital to all the values being correct. When I start each day, I run C3 to align on 3 axis. If I am referancing the top of the material for my Zzero, I run C2 to zzero. If I'm going to be referencing the surface of the spoilboard as my zzero, I C73. I use Shopbot Link which throws a lot of other wrenches into the smooth running gears. After running C73, I have to MZ to the thickness of my material and then do a ZZ to set my zzero reference.

    Since you just got this machine and are new to ATC operations, I would suggest running the entire course of alignment routines. Using an ATC is very different from a machine that does not have an ATC. This is something I struggled with when I added an ATC to my machine. All of a sudden zero references are very different. Zzero reference was the toughest for me to get my head around. You have to make sure all the other alignment routines are run successfully first, because all the ATC code uses these routines to determine where it is in the world. Everything runs of proximity switches with the ATC, especially the Z proximity switch. If you don't have the instructions for a full ATC alignment, ask the Shopbot folks and they can walk you thru the whole thing. I can't stress enough how vital this initial alignment is.

    I ran my PRSAlpha from 2009 until last year without an ATC and then got the ATC. Took me a couple of months to get things ironed out and fully operational to where it now purrs along very nicely.
    Don
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  7. #7
    Join Date
    Sep 2015
    Location
    Buford, GA
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    Default

    Thanks for all your input.

    The guy who sold it to me (and delivered it) helped me set it up. We ran the CN74 program to calibrate the clip locations. We loaded the tools into the collets and ran the CN72 routine. We then ran the CN73 routine to set the table offset.

    "When I start each day, I run C3 to align on 3 axis. If I am referancing the top of the material for my Zzero, I run C2 to zzero." - exactly what I do.

    "run a file and then check again after the file runs to see if it moved. Bits can slip in a collet sometimes as well." - If the bit slipped, it would cut too deep. Mine is consistently not cutting deep enough.

    "Make sure your cutting file does not have a start depth in vectric. (the box above the desired cutting depth)" - I don't fully understand this. I'm using the same post processor that I used for years on my old PRT. Why would it behave different on this machine?


    Today, I re-skimmed the spoilboard so it was fresh. I re-ran CN73. Then I ran a file that basically cut out 3 circles with some interior detail. I initially programmed it to cut 0.015" into the spoilboard, but it did not cut through. So I modified the program to cut into the spoilboard 0.035" into the spoilboard. In the two corners (see image) it cut into the table approximately 0.025", and in the middle, RIGHT WHERE I SET Z-ZERO (red x), it not only didn't cut into the spoilboard, but left material that I had to manually remove. This is right after a fresh skim and a fresh CN73.

  8. #8
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  9. #9
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    Sep 2015
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    Buford, GA
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    So, I turn the vacuum system on when skimming, which I learned with my last vacuum table. Now, this seems preposterous to me, but I'll go ahead and say it.....

    Is it remotely possible that the actual table for my machine, becomes concave once the vacuum is on? In that the center portion sinks down and the outer portions pull up? Making, in effect, a 96" x 48" bowl, which allows the edges to cut through but not the center?

  10. #10
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    You should not be using the same processor for the atc machine that worked on the old prt. Not the post processor anyway. And yes the bit can slip both directions. I'll post of pic of the start depth box
    Kenneth

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