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Thread: CNC - calibration issues for inlay work

  1. #46
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    Quote Originally Posted by Brad Shipton View Post
    Good job sourcing your problem. I always sigh a great relief when I finally find a problem. So many times I forget to write down the changes made or the problem I was having...

    Mark's squareness test is great. For me, when I have butt joints between panels, I hate to see gaps. I use Cabineo connectors frequently for boxes, and re-cutting parts annoys me.
    I confess that one reason I post issues is so I can easily go back and read through the suggestions/discussions if I ever forget what I did to get to the point that something is now working. This is probably not a unique position but now it's out there for not only others but for me to review.

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

  2. #47
    So, David, it appears that the difference in toolpaths that cured your problem was simply doing the pocket cleanup pass twice?

  3. #48
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    No sir, it was changing from 2D Contour to 3D Contour. Apparently the algorithm driving 3D toolpath generation is different from the one driving 2D toolpath generation. That it allows a second finishing pass was just a bonus and to me completely removes any hint of deflection in the first clean up pass. Not that there would be any measurable amount of deflection on a 0.005" cut, but it only adds a few seconds on these small inlays.

    I have subsequently test other pockets since this post and have found that 2D Contour is consistently smaller than 3D Contour when cleaning up the sidewall on a pocket. I used 2D Pocket to clear the bulk of the material and 3D Contour to finish the sidewall.

    David
    Last edited by David Falkner; 02-04-2020 at 3:35 PM.
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  4. #49
    Can you explain in any more detail the difference between the 2d and 3d contour toolpaths? Is the bit directed to different coordinates? I ask because I use a different cad/cam program (VCarve Pro) and am wondering if the approach is transferable.

  5. #50
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    David, the 48" aluminum rule I mentioned earlier is a bust. I received it today and checked it with both my 36" and 40" existing steel rules and at 36", it was nearly 1/16"/1mm off as shown in the photos below. The two steel rules are spot on identical, despite one being from Lee Valley (36") and the other from Woodcraft (40") I already processed the return with Amazon.

    Ends aligned exactly flush
    IMG_6634.jpg

    Variance
    IMG_6635.jpg

    Control comparison of steel rules
    IMG_6636.jpg
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #51
    In your picture, it might be an optical illusion but it appears as if the starting end is damaged. looks like one corner is rounded and the other has a sharp 90 deg bend but is dented. Maybe it was damaged in shipping or before shipping.

  7. #52
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    That's a significant difference! I would also send it back.

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

  8. #53
    Quote Originally Posted by Jim Becker View Post
    the 48" aluminum rule I mentioned earlier is a bust.
    We have sold our soul to the devil which is the deceptive cheap option. And the cost of the returns monetarily and to the planet is a double pennance on our souls.

  9. #54
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    Quote Originally Posted by Kevin Jenness View Post
    Can you explain in any more detail the difference between the 2d and 3d contour toolpaths? Is the bit directed to different coordinates? I ask because I use a different cad/cam program (VCarve Pro) and am wondering if the approach is transferable.
    I really don't know, Kevin. I recall reading a year ago something about using 3D profiles for finishing toolpaths, that it served better than 2D though I have used 2D for an awful lot of my cuts. But I can't find where I read/heard that comment.

    One thing I know about the difference in 2D and 3D toolpaths in F360 is that 2D is a 'dumb' tool; you have to select everything you want to cut. 3D is the exact opposite; all you need to do is select the tool you want to use and it will generate the toolpath. It's basically a subtractive method because it selects everything and you tell it where you don't want to cut. Why the contour cut with 2D profile cuts different than 3D profile is beyond me at this point.

    I plan to keep looking and doing my research but all I know at this point is that, for now anyway, when I need to hold a tolerance or hit a number I'll use 3D Contour.

    This may not help in the Vectric world but maybe something will apply.

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

  10. #55
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    Quote Originally Posted by Mark Bolton View Post
    We have sold our soul to the devil which is the deceptive cheap option. And the cost of the returns monetarily and to the planet is a double pennance on our souls.
    Fortunately, they pay for the returns, not me. I got back every penny including sales tax about two hours after I received it and then dropped it off at the UPS store to be scanned. I wasn't expecting something extraordinary, but this was bad enough.

    In your picture, it might be an optical illusion but it appears as if the starting end is damaged. looks like one corner is rounded and the other has a sharp 90 deg bend but is dented.
    I looked at that, too, but made sure that the lines for the start point were, well...lined up...not just that the ends were flush.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #56
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    Quote Originally Posted by Kevin Jenness View Post
    Can you explain in any more detail the difference between the 2d and 3d contour toolpaths? Is the bit directed to different coordinates? I ask because I use a different cad/cam program (VCarve Pro) and am wondering if the approach is transferable.
    Hi Kevin,
    Fusion 360, VCarve Pro, and other similar cad/cam programs will only do what they are told to do, and produce machine specific g-code that reflects these instructions. I suspect that the original problem of part dimensions not matching the drawing was not due to any deficiency with Fusion 360, but had more to do with the CAM strategy implemented by the programmer. Fusion 360 is a very sophisticated CAD/CAM program that incorporates many levels of machine control options. I think the best option for those interested in learning about this would be to visit the AutoDesk Fusion 360 support pages listed below.

    David


    http://help.autodesk.com/view/fusion...2-14056A2B1CFE

    Fusion 360 2D Milling Toolpaths.jpg

    http://help.autodesk.com/view/fusion...2-14056A2B1CFE

    Fusion 360 3D Milling Toolpaths.jpg

  12. #57
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    Quote Originally Posted by David Falkner View Post
    Nice looking setup, David, very clean. Do you not use any backlash compensation in your software or is it just not on this screen? Just curious...

    David
    It's just not on the screen. Photos were taken previously. Here are the current settings.
    David

    20200205_004618_resized.jpg

  13. #58
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    Quote Originally Posted by David Buchhauser View Post
    ...I suspect that the original problem of part dimensions not matching the drawing was not due to any deficiency with Fusion 360, but had more to do with the CAM strategy implemented by the programmer. Fusion 360 is a very sophisticated CAD/CAM program that incorporates many levels of machine control options...
    Well said, David. I fully agree. I also know it's a LOT more powerful and function filled than I'll ever use.

    Quote Originally Posted by David Buchhauser View Post
    It's just not on the screen. Photos were taken previously. Here are the current settings.
    David

    20200205_004618_resized.jpg
    I figured you had some sort of setting in there. That would truly be an awesome R&P machine if you didn't need any backlash settings!

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

  14. #59
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    I'm a late to this party, but in my experience the most accurate and readable scales are the satin chrome ones from Starrett. I have several from 6" to 48", and the lines are very finely scribed, it's easy read them to 1/64's or .010" with a loupe or optivisor. They are expensive, but turn up at auctions and on ebay. The coefficient of thermal expansion for steel is half that for aluminum, and it holds up much better to handling

    I doubt it's necessary for woodworkling, but I like working to that level of accuracy. I acquired mine early in my career, got plenty of use from them. Also bought a 4' bevel edge Starrett 280 straight edge. Again pricey, but super accurate and a great reference for checking rulers, machine tables and setting up machines. Over the last 45 years it's been indispensable.

  15. #60
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    Here's an update on the inlay testing using some Walnut and Maple. I had a few minutes this afternoon and cut a small circle, an arc, and a larger circle (think, portion of a Longworth chuck).

    All the settings were as I specified before but ignore the first set of pockets. No matter how much you 'know' what to do if you type the wrong values the pocket won't be the correct size.

    The pockets are 0.006" larger than the inserts and fit nicely (0.003" per side). I really could make it 0.002" per side but 0.003" certainly makes it easy to get the inserts in with glue. The pockets are 0.150" deep and I cut the inserts 0.1875" thick to leave a little sticking out for sanding flush. Also, I cut the inserts upside down so I don't have to clean up the tabs and the extra 0.0375" is enough that I can lightly trim them and the inlay fits.

    I glued these into place, gave a quick 5 minute French polish (2# cut, light amber color), and took some photos, so nothing elaborate but you'll get the idea. I'm pleased with the fit on these inlay pieces.

    001 - Arc, circles - inlay test.jpg

    002 - Arc, circles - inlay test.jpg

    003 - Arc, circles - inlay test.jpg

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

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