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Thread: World Map

  1. #16
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    Quote Originally Posted by Kris Cook View Post
    John - just a thought. Is there enough thickness to make some relief cuts on the back? Would that help with the warping long-term?
    I thought about that, Kris, but it's only about 1/4" thick at the bottom of the carving. It's cupped less than 1/8" now. I hung it on the wall today and it can't be seen. BTW, I used a new to me picture hanging system. The wall I hung it on has a pocket door inside, so I had to use something that would work with the approximately 3/4" thick plaster coated drywall without going through. These worked great.

    https://www.homedepot.com/p/PicGenie...MK4S/306800860

    John

  2. #17
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    Quote Originally Posted by John TenEyck View Post
    I used a 1/4" BN EM with 40% stepover for the roughing cut. Then I used a 1/8" tapered ballnose endmill for the clearing finishing pass at 6% stepover, followed by a 1.5 mm tapered BN EM with 8% stepover for the finial finishing pass. I'm using VCarve Pro. The key one in my opinion was with the 1/8" tapered BN EM, because it's the one that does the finishing work on the surface of the hemispheres and deep flat areas. Having said that, a guy on the CNC forum I participate on said hogwash, forget the two step approach and just run the 1.5 mm bit with 8% stepover on a 45 deg raster cut. And he even said at 300 ipm. I don't know if it would look as good, but the simulation does look good, and takes the machining time down from over 48 hours for the two-step finishing approach to around 13 hours. I don't plan to make another one of these but when I do something similar I definitely will try a test piece to see how his recommendations work.

    John
    You'll really have to do some experiments with what works best with your machine for these cuts relative to paring down. I generally have used a tapered BN for a single finish cut about the same size as you. You may need to adjust your Z speed in VCP as it's often set quite slow compared to the horizontal feed speed and Z is a "yuge" factor in cut time for 3D models. I frankly set it at about the same as the horizontal speed and let the machine deal with how fast it can actually move. Your step overs are reasonable for fine detail, IMHO.
    --

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

  3. #18
    That's really nice!
    "All that is necessary for the triumph of evil is that good men do nothing."

    If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.

  4. #19
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    I set the plunge (Z) speed to 120 ipm, for the long finishing passes. That's the maximum rate for the stock Z-axis on my machine, so I can't go any faster with that parameter. In all cases, that's faster than the recommended plunge speed for the bits I used, by up to 3X. You might want to look into that with your 3D carvings.

    John

  5. #20
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    John Thanks for replying back to my post.
    The map is the coolest piece Ive seen made with cnc.
    Good Luck Always
    Aj

  6. #21
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    Quote Originally Posted by John TenEyck View Post
    I set the plunge (Z) speed to 120 ipm, for the long finishing passes. That's the maximum rate for the stock Z-axis on my machine, so I can't go any faster with that parameter. In all cases, that's faster than the recommended plunge speed for the bits I used, by up to 3X. You might want to look into that with your 3D carvings.

    John
    I generally set the Z to about 200 ipm if the horizontal speed is running in that range. The machine will never exceed what it's capable of, of course, but it will also not be limited to some artificially low value since 3D carving naturally has a whole lot of Z axis action to do the job. My machine has 900 oz NEMA 34 steppers and there's an air assisted counterbalance on the Z axis to counter the weight of the spindle for best performance up and down, particularly in the up direction...the stepper doesn't' have to work so hard lifting the heavy spindle.
    --

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

  7. #22
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    Quote Originally Posted by Jim Becker View Post
    I generally set the Z to about 200 ipm if the horizontal speed is running in that range. The machine will never exceed what it's capable of, of course, but it will also not be limited to some artificially low value since 3D carving naturally has a whole lot of Z axis action to do the job. My machine has 900 oz NEMA 34 steppers and there's an air assisted counterbalance on the Z axis to counter the weight of the spindle for best performance up and down, particularly in the up direction...the stepper doesn't' have to work so hard lifting the heavy spindle.
    As you said, there's a lot of wasted time with the Z-axis when doing 3D carving. I'm limited to 120 ipm, no matter how high I set it, so there's nothing to be done unless I want to upgrade to 1F's new heavy-duty Z-axis which has a faster max. speed. At this point, I'd get a spindle before spending even more on the new Z-axis. From what some are suggesting on the CNC forum I look at, there are other ways to potentially reduce carving times, so I'm going to explore those first.

    FWIW, the little Makita router showed no signs of problems running those long carves. It's removing so little stock it doesn't even get warm. I'm sure the runout is higher than with a spindle, but the results speak for themselves, whether doing carvings where it probably matters less, or cutting parts for clocks where it does really matter. A higher level machine would be nice, but at this point there's no burning need to justify the money. I haven't paid off the money I have in this one yet, but I will.

    John

  8. #23
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    I was only relating to how I put the settings on my machine and why, John, and making no negative commentary or comparisons.

    As to carving time, a lot of that is figuring out what stepover does the job for acceptable surface quality. It can be amazing how the expected carve time changes. While I honestly don't trust the time estimates in the Vectric software relative to actual accuracy, they are at least good for comparing what the effect of changes are to something like stepover. A few years ago when I was doing those magnolia carves for a big old house (and completely new to 3D modeling/carving) I had the same fun you are having right now trying to work out what was the best set of choices 'cause I wasn't going to sleep in the shop. (fortunately, actually can pause a job with some controllers when necessary for bathroom and meal breaks!)
    --

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

  9. #24
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  10. #25
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    I didn't take offense, Jim, I was just explaining the limitations I have.

    Too high a stepover on the first finishing pass is one of the reasons I had to do the carve a second time. I didn't realize that it was the final pass in some areas, so I set it at 20% to reduce the time; of course that left unacceptable ridges. I ended up using 6% stepover with that pass and that's what you see on the hemispheres.

    The time estimates in Vectric are only that, but they can be very useful if you are running similar projects, and if your machine provides a time estimate when you load the file. There is a scale factor in the time estimate window which you can adjust to bring the estimated time in line with the actual time on the machine. My machine gives a very accurate estimate of machine time when I load the file, within a second, so I know how long it's actually going to take, and can go back and adjust the scale factor in Vectric if it's off, and also rethink the machining strategy if it's unacceptable. My machine has a pause feature, fortunately, which works seamlessly, at least so far. On these 24+ hour toolpaths I would start them whenever I got to, hit the pause button before bedtime, and hit the run button when I got up the next morning. I let them run whether or not I was in the shop, but never if I was going to leave home. I have a Wyze camera on it and can check it on my phone, and I go physically check if I hear anything odd. It's not loud upstairs, but I can hear it humming and moving.

    John

  11. #26
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    I forget what the stepover was that I used for that "yuge" carve I mentioned, but I think it was in the 8% or so range for the finishing pass. I didn't do it diagonally as these were 4' long pieces, so I followed the grain on the axis I had the workpiece oriented to; y in my case.
    --

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

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