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Thread: Anyone installed a spindle at an angle?

  1. #11
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    Chris, in that sample you show there the bit would almost never be "normal" to the face of the part, so even on a 3 axis machine you'd still, for lack of a better word get that "tilt" that you want.

    That Harvey tool article makes sense if you're something like metal where you can't sand it afterwards. In my view doing a contoured surface like that doesn't justify multi axis unless there are parts you literally cannot reach with a 3 axis machine.

    That all being said, you are limited on the shapes that you can make with a 3 axis machine. 5 axis opens up a whole new level of creativity.

    Perhaps you could get one of these:

    https://www.amazon.com/Router-Machin...605561&sr=8-14

    Bolt it to your table, and run the axis from your ShopBot control. Depending on the vintage of your control board you may have the IO to run something like this.

  2. #12
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    The factor requiring sanding in my 3d work is not the actual cutting but the ridges left by the stepover. I can follow your thinking on not cutting with the bottom of a bullnose but in reality the cove cuts from a bullnose are fine and usually don't need sanding. It is the ridges from the stepover which need sanding. The same stepover should yield the same ridges regardless of the angle of attack so I fail to see the advantage if you are trying to avoid sanding.

  3. #13
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    Quote Originally Posted by coryatjohn View Post
    Maybe I'm a freako here but I really enjoy doing the final, detailed sanding of a nice piece I'm working on. It puts a bit of humanity in an otherwise mechanical work. The amount of effort required to finish off something like that little flower is minimal. Why not just hand sand it?

    I really enjoy doing the final, detailed sanding too, Coryatjohn, and I can't imagine how much time it would take to do large curved surfaces completely smooth without sanding. I actually wrote "I don't want to be sanding to such an extent the finished item has a surface that's not very close to what it should be by design".

    I have done finishing passes from 2 perpendicular deirections and from 3 directions (at 60 degrees from each other) to leave a minimal amount of sanding, and you can increase the speed on the 2nd and 3rd passes of course if you want since they're only crossing small ridges.

  4. #14
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    Quote Originally Posted by EricSchimel View Post
    Chris, in that sample you show there the bit would almost never be "normal" to the face of the part, so even on a 3 axis machine you'd still, for lack of a better word get that "tilt" that you want.

    That Harvey tool article makes sense if you're something like metal where you can't sand it afterwards. In my view doing a contoured surface like that doesn't justify multi axis unless there are parts you literally cannot reach with a 3 axis machine.

    That all being said, you are limited on the shapes that you can make with a 3 axis machine. 5 axis opens up a whole new level of creativity.

    Perhaps you could get one of these:

    https://www.amazon.com/Router-Machin...605561&sr=8-14

    Bolt it to your table, and run the axis from your ShopBot control. Depending on the vintage of your control board you may have the IO to run something like this.
    Hello again Eric - you've hit the nail on the head by pointing out that in the example I posted the ball end cutter would almost never be "normal" to the face of the part. That's exactly right and very important. Basically even by leaving the ShopBot as it is, without installing the spindle at an angle, when the surface has curvature most of the cutting is done away from the very centre of the cutter. The steeper the part of the surface, the further from the very end of the cutter.
    I'm clear now that the tilted ("off normal") strategy is really only for 5-axis machines that can calculate and then deliver a consistent angle and appropriate direction of cut to really deliver the potential benefits.
    It's been a great help to 'discuss' this with others instead of just deciding in my own head that it would be a good idea to install the spindle at an angel - I've got through to understanding what was originally suggested by most if not all of you - it's not worth it on a three axis machine.

    As regards the extra two axes on the little machine in the link: if something similar but larger (sturdier, stronger, larger motors to resist the forces of milling with the 3 axis machine the part being held), AND if it could be connected ("integrated") to the ShopBot control relatively easily, I could be interested. (Careful now guys - or I'll start another thread asking if anyone knows if anyone has added 2 extra axes below their 3 axis ShopBot).

  5. #15
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    "I'm clear now that the tilted ("off normal") strategy is really only for 5-axis machines that can calculate and then deliver a consistent angle and appropriate direction of cut to really deliver the potential benefits"

    The machines don't do this calculation, the CAM software does. As an example, Fusion does 2.5D milling, 3+2 milling, and continuous 5 axis milling. The latter is a little misleading, I'll get to that...

    2.5 is what Vectric does, and what 99% of us ShopBot users do all the time.

    3+2 is like this: Imagine you had your ShopBot 3 axis machine, but you had that A and B axis table I linked earlier. When you run a job the A and B axis move to orient the part to the spindle at whatever angle you setup in CAM, then it runs a 3 axis toolpath. So while it's techincally "5 axis machining" it's kinda fake. It's fine for a lot of jobs, but a real pain on something like milling a bust of someone's head as you need to break up a 3D surface into a bunch of separate toolpaths.

    The continuous 5 axis machining in Fusion is limited to only the most very basic swarfing and countour following toolpaths. It won't do the 3D carving you want. To actually get continuous 5 axis you have to spend far more than your machine is worth.

    3+2 is likely fine for the part that you showed in your example.

    I'm not sure what the stock size you're starting with is, but you might be able to use that table I linked. Figuring out the max machining envelope is tricky. You can use the PocketNC simulator here to get an idea of that: https://sim.pocketnc.com/

    As far as the strength for machining, that one is probably good if it can hold your stock. The strength comes in metal that it's made from, what it's bolted to, and the holding power of the stepper motors. You could probably but some big stepper drivers on those motors and get some pretty good holding strength.

  6. #16
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    I usually don't have time restraints on 3d projects. So, if I have a job that requires a smoother surface with little, or sometimes no sanding, I found taking .001" off on a final pass gets rid of most of the fuzzies to the point that the part can be cleaned up with a few swipes with steel wool here and there.
    Particularly helpful if the part has some fine detail that sanding may knock off.

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