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Terrco Northstar Carver/Duplicator CNC Conversion

Discussion in 'CNC Mills/Routers' started by Canis, Feb 22, 2016.

  1. Canis

    Canis Well-Known
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    10392448_10152297916598359_4008921610988772609_n.jpg

    Hello. I am in the initial stages of converting my Terrco Northstar carver/duplicator to CNC operation. The unit has two 1hp spindle drives and is manually operated at this point. The stylus on the left is used to follow a workpiece (such as a guitar body) and the machine carves up to two copies.

    northstar relief carving.JPG

    The table top is removable to access a spindle mechanism that allows full 3D duplication of objects, such as gun stocks or wooden decoy ducks. There is a manual crank on the left side that rotates the mechanism.

    northstar spindle.JPG

    My goal is to convert this machine to CNC by moving the stylus with a 2ft by 4ft gantry. I have looked around for information and am overwhelmed by the options.

    Has anyone done a similar conversion?

    Any help or advice is much appreciated. Thanks.
     
    GrayUK likes this.
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Looks like an interesting project and should be fairly simple to accomplish. A simple drop-in system with the stylus riding on top of the Z-axis would probably be easiest. What is the 3D range of motion for the stylus?
     
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  3. Canis

    Canis Well-Known
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    Thanks for the reply. The range of motion is 48" x 24" x 8"
     
  4. Canis

    Canis Well-Known
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    I can see the mechanical aspect being fairly simple, but am unsure which route to go with controls. My goal is to use open source (and free :) hardware and software as much as possible. Thinking Arduino etc. No idea what to use for CAD/CAM software. Starting from scratch. Any help suggestions are greatly appreciated.
     
  5. GrayUK

    GrayUK Master
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    This project will be a good one to watch. :thumbsup: It seems to be a novel and useful machine to start with.
    If you don't mind, it would be great if you can please keep us up to date on how it goes. :)
    Cheers
    Gray
     
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  6. Canis

    Canis Well-Known
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    This will be my first CNC, and I'm really hoping for some guidance and advice from this group in terms of hardware and software selection. Based on initial research, I'm aware of the steep learning curve I'm facing, but am hoping that with your help I can avoid some costly beginner's mistakes by drawing on your collective knowledge and experience.
     
  7. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Don't get your hopes up too much on the "free hardware" ;) but free software shouldn't be a problem. The motions the machine will be going through are really no different than a standard CNC machine so there is no real reason you shouldn't be able to use the standard Sketchup/Sketchucam software combination or any of the other Grbl software that works with Arduino based boards.

    From the mechanical side, the only potential issue I see is making sure the Z-axis is substantial enough to handle the 8" of vertical motion without wobble at its max range. Doable, but definitely will need some thought. I am assuming the feedback on the stylus is roughly equivalent to the force of the bit cutting???
     
  8. Canis

    Canis Well-Known
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    Well, not looking for "free", just "cheap" :) Having said that, I am willing to pay for anything that is needed to make this a good machine.

    The Z-axis will be more like 6" max, maybe less depending on the bits used. The electric motors touch the table at 8".

    Yes, the machine is fairly well balanced by design. The motors are balancing some of the force on the stylus, and there is an adjustable counterweight to fine-tune the assembly mechanically. The front to back movement is very smooth as well. Still, I would want to go with some fairly beefy steppers, preferably with position feedback.

    360° rotation of the pattern and blanks is accomplished through use of the center turning crank. Would like to motorize that as well.
     
    #8 Canis, Feb 22, 2016
    Last edited: Feb 22, 2016
  9. Canis

    Canis Well-Known
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    Starting with hardware, would screw actuators be a good way to go? I need something beefy to move the whole gantry assembly back and forth and potentially cut with both spindles. What would be a good value solid way to drive this? Also, what kind of motors are best? I would like to have position feedback and speed control if that is possible to do for a reasonable amount.

    Since there are some unknowns, I would like to err on the side of caution and over-build it instead of trying to cheap out and have a machine that doesn't perform well. I understand that this is a different type of build and some guesses need to be made. Thing is that my guesses could well be wrong.

    Again, I appreciate any help and suggestions from people with a whole lot more experience and knowledge...
     
    #9 Canis, Feb 22, 2016
    Last edited: Feb 22, 2016
  10. GrayUK

    GrayUK Master
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    I would go for screws definitely. I think they would lend themselves quite well. :thumbsup:
    Perhaps Nema 34s maybe or 4nm Nema 23s? I would have to see a video of it in action to get a better idea of stresses involved and at which points.
    Have you used SketchUp? It is a great program to get your ideas down on paper, so to speak. It is however, until you get used to it, just about the most frustrating program I've ever used. :banghead:
    Cheers
    Gray
     
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  11. Canis

    Canis Well-Known
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    I'm aware of SketchUp, but have never used it. I don't have a video of my own, but here is video of a factory one with only one carving head:



    Here is another one of a 4 head unit that shows the geometry and some good quality detail:



    My machine has two drives and spindles, so is just shorter than this one.
     
  12. Canis

    Canis Well-Known
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    Here is a link to my machine.

    NorthStar | Terrco Inc


    I have the 20-2 with the 1hp drive option. The manufacturer site lists "Electric center turning mechanism" as an option. I am assuming that replaces the manual crank for the spindles on my machine. If that is the case, I should be able to turn mine with a stepper motor as well. I'm thinking that would be the 4th axis.
     
  13. Canis

    Canis Well-Known
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    Are there any good hardware kits out there that anyone here can suggest? I have looked around but am overwhelmed. There are just too many options.
     

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