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Thread: Calibration question

  1. #31
    Sounds like you must have knocked a lot of your problem out with the Y issue and the 1/16". Wonder if you stretched that out as far as you possibly could if you'd get closer and closer. As frustrating as these type situations are to me when we deal with them, it sure is rewarding to work your way to a good solution.

  2. #32
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    I find no recommendation on the rack lube and I seem to have read someplace to use the same grease as you have posted in the grease fittings for the rail. I do see on the FLA he guarantees this for the R&P systems.... Now in practice, the backlash on the system is going to limit accuracy and repeatability. With our machines, out of the box you can reasonably expect and we guarantee accuracy and repeatability to be within 0.002-0.005" per linear foot. With a little tweaking, our users are reporting getting 0.001" accuracy on smaller feature parts

    I had a PlasmaCam CNC plasma cutter for several years, it had R&P on the X - Y Axis and I never recall putting any lube on those. That plasma dust was everywhere, even after 10 years I am still finding it!!
    Last edited by Bill George; 08-15-2018 at 9:54 AM.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  3. #33
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    Quote Originally Posted by Mark Bolton View Post
    Sounds like you must have knocked a lot of your problem out with the Y issue and the 1/16". Wonder if you stretched that out as far as you possibly could if you'd get closer and closer. As frustrating as these type situations are to me when we deal with them, it sure is rewarding to work your way to a good solution.
    I'll find out tomorrow how close it is because I need to cut the new Walnut and Maple stripes plaque. Before I do that, though, I'll do as you suggest and use the entire length of the bed for my Y test. It's only 6" more than what I used but it could make a difference. Thanks, Mark!

    David
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  4. #34
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    Update - I planned to cut the stripes plaque but decided instead to test the machine to its full capacity of 26" x 50" and calibrate to that instead of the way I did it the other day using partial travel. So, now I am comfortable that when I plug in a dimension I will get that dimension, at least as close as I can measure.

    So here's the new issue - gantry squareness.

    Let me see if I can explain this properly:
    1. Using Fusion 360 I generated a toolpath for a 23” square and then an offset 1/32” to the inside. My spoilboard is only 24" wide and I wanted the cut inside the edge of the MDF for obvious reasons.
    2. I set a depth of 1/32” with a 60° V-bit and cut the square into the spoilboard.
    3. I then measured the inside points at the corners (I put a black dot on the inside point to see it better).
    4. When I measured across the diagonals I found one is 32 7/16" and the other is 1/32” shorter, might be slightly less than that by 0.010" or so.
    5. The proper measurement should be 32.439” which is close enough to 32 7/16” (32.4375”) and given the distance that’s as close as I can measure anyway.
    6. What now? Is this within tolerance or should I expect closer? I rarely cut anything that large so the error of <1/32" in a 32" diagonal may just be as good as it's going to get - or is it?

    I realize the actual measurement is not relevant, just that the diagonals are the same measured with the same device. I’m glad it’s actually very close to what Fusion 360 says it should be, though, and might be right on though I can’t measure to a couple of thousandths over that distance.

    Here are a few photos to support my description above -
    Calibration square set up - 23 inch - 8-17-18.jpg

    Calibration square - CNC.jpg

    Calibration square - 23 inch - 8-17-18.jpg

    David
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  5. #35
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    So that's .03125 or a .032 of an Inch over 32 Inches. I am surprised you can measure that with a steel ruler.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  6. #36
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    Quote Originally Posted by Bill George View Post
    So that's .03125 or a .032 of an Inch over 32 Inches. I am surprised you can measure that with a steel ruler.
    It's probably slightly less than that, Bill. What I can easily see is that one diagonal is right on 7/16" and the other diagonal is halfway between 3/8" and 7/16", so I would call that 13/32" and that's pretty easy to see. Because it is very slightly closer to the 7/16" than 13/32" I'm going to say it's probably closer to about 0.020" under. But like I said, the measurement itself isn't really that critical, although I'm glad it matches what Fusion 360 says it should be, but more importantly that the diagonals are identical.

    Tomorrow I'm going to extend that out to the maximum I can engrave on the spoilboard and that will be right at 23" x 47". I mounted the spoilboard back a couple of inches from the front and that means I can't engrave the full 50" capacity. Once I cut those rectangles I'll check the diagonals on a far greater distance and see how close they are.

    David
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  7. #37
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    You should be easily able to adjust that out with independent auto squaring if your control has it, most decent ones do
    Gary Campbell
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  8. #38
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    Quote Originally Posted by Gary Campbell View Post
    You should be easily able to adjust that out with independent auto squaring if your control has it, most decent ones do
    I'll see tomorrow how far out it is on the full spoilboard, Gary, but how do I go about the auto squaring? I'm asking before I have done any searches but if you have a procedure you can point me to that would be great.

    I'm using Mach4 and ESS if that helps.

    Thanks!
    David
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  9. #39
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    David, it would be interesting for Gary and others on here to share the results of the tests your doing and done on their machines.



    Mine is still waiting on the "special order" 5x8 sheet of MDF to come in, after all this is Des Moines Iowa. Only Two real lumber yards left after the big box stores moved in, only one was willing to order in. Gee I wonder why the big box stores are taking all the business?
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  10. #40
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    "
    So that's .03125 or a .032 of an Inch over 32 Inches. I am surprised you can measure that with a steel ruler."
    I am not surprised, and in fact you should be able to get much closer than that, especially if using a USB microscope

    "
    David, it would be interesting for Gary and others on here to share the results of the tests your doing and done on their machines"
    Interesting, maybe, but serves no viable purpose to assist David in getting his machine dialed in. One should assume that CNC mfgr's and those that build numerous machines every year have methods and especially equipment to calibrate their machines easier, faster and to a higher level of tolerance than those that build one or two in a lifetime.
    Gary Campbell
    CNC Replacement & Upgrade Controllers
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  11. #41
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    I just ran the calibration rectangle at twice the length of the square for a greater distance - 23" x 46". The results are that it is double the error of the 23" square. That was a little under 1/32" off and this is a tiny bit under 1/16" off on the diagonals.

    Fusion 360 says the diagonal should be 51.43" and I'm measuring 51 7/16" (51.4375") - close enough to 7/16". The other diagonal is measuring 51 1/2" or a tiny bit under but very slight. So for all practical purposes I can call it 1/16" greater distance.

    So same question - is this enough to correct (it is to me, btw), is it best fixed by mechanical means, and/or if it's fixable in software how do I accomplish that?

    I'm running Mach4 with ESS, proximity sensors on Y are on the X- side only but I do have two steppers on Y.

    This graphic may help -
    Calibration rectangle - 8-18-18.jpg

    David
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  12. #42
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    Isn't that within the published specs for the machine?
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  13. #43
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    Remember that the difference is divided by 2 so it is only off by less then 1/32

  14. #44
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    Quote Originally Posted by Jerome Stanek View Post
    Remember that the difference is divided by 2 so it is only off by less then 1/32
    Well I check the CAMaster website and the Fine Line Automation website, neither claims x .001 over 3 ft, 4 ft or whatever. Both claim +/- .001 repeatability.

    Fine Line says Accuracy +/- 0.005 in (0.127 mm) or better
    Repeatability +/- 0.001 in (0.025 mm BTW Mine was not a bolt together kit, welded frame and gantry.

    CAMaster all I could find was +/- .001 repeatability.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  15. #45
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    Quote Originally Posted by Bill George View Post
    Well I check the CAMaster website and the Fine Line Automation website, neither claims x .001 over 3 ft, 4 ft or whatever. Both claim +/- .001 repeatability.

    Fine Line says Accuracy +/- 0.005 in (0.127 mm) or better
    Repeatability +/- 0.001 in (0.025 mm BTW Mine was not a bolt together kit, welded frame and gantry.

    CAMaster all I could find was +/- .001 repeatability.
    Repeatability is just that it will be out the same every time.

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