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Thread: CNC w/ Fourth Axis or Duplicator Lathe

  1. #1
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    CNC w/ Fourth Axis or Duplicator Lathe

    I maintain a limited space but I've been weighting the prospect of a small CNC machine.

    I have a product planned which will require turnings and complex shapes. I stumbled upon the ShopBot Buddy and it looks interesting and expandable. However, I wonder if a dedicated turning tool like a duplicator lathe would be better than a CNC fourth axis. The cost of the fourth axis is nearly that of a dedicated lathe, but does not require additional floor space.

    I don't have a need for a serious volume, maybe 40 - 80 turnings at a time, which on a duplicator lathe I would expect that to be a day or so. With a CNC that does not automatically feed new material into the lathe I would expect to have my time pretty much dedicated to the turning work during that particular operation so whether or not I'm actually doing the cutting seems moot.

    So, I'm open to thoughts from those with experience in this regard. Is the fourth axis painfully slow or surprisingly quick? For the buddy I am considering the one with a spindle rather than a router.
    Bumbling forward into the unknown.

  2. #2
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    How much CNC and how much 3D design experience do you have?

    I am biased toward the CNC router because when your not doing turnings you could be doing other router work. As far as router vs spindle I have used both, and the spindle is faster and less noise but mine is water cooled and than can be an issue if your shop is subject to freezing and keeping the liquid clean and algae free. I have limited experience with a 4 axis on any CNC.
    Last edited by Bill George; 12-26-2017 at 8:33 AM.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  3. #3
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    Zero CNC experience. I build many of my designs in Sketchup Pro before producing them by hand. I have also worked on Autocad. I have the expectation that the computer aspect of this will take some time but will not be especially daunting for me.

    So, I'd like to consider this in the context of once up and running, I don't want to weight the learning curve into it.

    No risk of freezing in my shop and very little dust.
    Bumbling forward into the unknown.

  4. #4
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    Brian...
    The answer is relatively simple. If the turnings can be done on a duplicator lathe then that would be the most efficient way to do them...by far. There are very few viable commercial applications for 3d cutting using rotary axes due to the time that it takes to raster back and forth the length of the part. If the part has details on it that are 3D in nature that could not be cut on a lathe, then the rotary axis is the only choice. A third option, a CNC wood lathe may be the desired product.

    For example, a 20" long 1.75" diameter spindle of sorts. Using the default 10% stepover on a 1/8" tapered ballnose it would take 440 passes to cut the spindle. Those passes would take 7 to 18 seconds each depending on how many sharp, (speed reducing) artifacts are in the design. Using an average of 10 seconds per pass the resulting time is 73 minutes, and that's after the blank had been rounded (another 3 minutes). A copy lathe should do them in about 6-7 minutes or less depending on the experience of the operator and his roughing skills. The 10 to 1 ratio is pretty common.

    The next issue you will run into, is the Buddy you are looking at an Alpha? That type of constant back and forth motion is not what ShopBot's standard was designed for. The Alphas are far more capable.
    Gary Campbell
    CNC Replacement & Upgrade Controllers
    Custom 9012 Centroid ATC

  5. #5
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    Thanks Gary! Very much appreciated. I'll plan on a separate lathe.

    As for the other parts they may still be well suited to CNC. I am considering an alpha version of the buddy since they mention it as being more geared toward regular production and if I'm not mistaken it can be outfitted with roughing tools when using a spindle. Certainly I'm not sure how serious a machine the alpha buddy is, however, or if it requires upgrading to become more capable.
    Bumbling forward into the unknown.

  6. #6
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    Brian...
    The Buddy is well positioned in its price class. As are most machines in todays market. If you look at all the machines in the sub $1k, $2.5K, $6k, etc, etc. classes you will see that they all are fairly equal. Each has some unique features that the respective marketing departments tout as "magic", but in reality they all are designed for a price class. Some spend more on frames, some on other items. All in all, they will all do the same things, albeit at different speeds, and with different effort on the part of the operator.

    All machines can use an upgrade. Including the Starship Enterprise, where the Captain was always looking for "more power" The reality is that if you are buying one now with the intent of upgrading it, then you may be looking in the wrong price bracket for your workload.

    Third option, CNC Wood Lathe: https://youtu.be/4j_GFr0spSE
    Last edited by Gary Campbell; 12-26-2017 at 10:39 AM.
    Gary Campbell
    CNC Replacement & Upgrade Controllers
    Custom 9012 Centroid ATC

  7. #7
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    Thanks Gary.

    Hah, that lathe is awesome. I had in mind a much more production type cnc lathe when you mentioned it, but something like that is certainly interesting to me. I take it this is something you make?
    Bumbling forward into the unknown.

  8. #8
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    Brian...
    I've made a few lathe conversions. That was from a few years back. The current models use a quick change tools post. More premeasured tools and less money. They also cut faster. Where that one could take .1 (rad) or .2 (diameter) per pass with the roughing tool, the newer ones will cut over .25" (dia) per pass.

    That same 3 1/4" blank using 3D tools on a rotary axis, roughed and finish cut was right around 85 minutes. You can see the lathe do it in under 4.
    Gary Campbell
    CNC Replacement & Upgrade Controllers
    Custom 9012 Centroid ATC

  9. #9
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    Thanks Gary, I very much appreciate your insights. I found one, with pricing, bit more than I would consider at this point but it's a nice idea. The duplicator seems a bit more tangible at the moment. Good thing it would seem that these can be retrofitted onto a good lathe.

    Considering a minimax duplicator lathe.
    Bumbling forward into the unknown.

  10. #10
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    MiniMax make a pretty good machine. I've owned a number of them. That lathe is about 1/3 the price of a similar sized CNC wood lathe
    Gary Campbell
    CNC Replacement & Upgrade Controllers
    Custom 9012 Centroid ATC

  11. #11
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    I've seen many positive comments about the minimax and I'm glad to see that you think highly of them as well. I do like that I can use an actual piece as the template rather than needing to make a template.
    Bumbling forward into the unknown.

  12. #12
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    That's why the CNC versions are so valuable, no template, no actual piece, just draw and cut!
    Gary Campbell
    CNC Replacement & Upgrade Controllers
    Custom 9012 Centroid ATC

  13. #13
    Brian, your going to the cnc world? Does this meen no more family crest for me to carve? Dan Nelson Nelson Woodcrafters.

  14. #14
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    Howdy Dan, keep me on file please I'm not sure I will make the leap.
    Bumbling forward into the unknown.

  15. #15
    Will do, either way good luck . I would not be afraid to take the plunge. Feel free to email me if you have any questions

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