Anyone doing subtractive?

Discussion in 'Tool heads & ToolChanger' started by Joe Pomo, Jun 7, 2020.

  1. Joe Pomo

    Joe Pomo Well-Known Member

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    I'm not Greg, but I would guess that it comes down to things like your 1. software, 2. milling settings, 3. printer resolution and 4. adhesion.

    I've used only an 1/8" flat end mill, but I've also been interested in smaller bits.

    1). Probably any CAM software, including F360, will let you define whichever milling bit you need and it will use that for all tool-path calculations. I can't speak for the ASMBL plug-in yet, but I hope to start diving into it soon. Since it's integrated into F360, I imagine tool-definitions are the same.

    2). F360 will give default settings and you'll just have to see what works best for you to avoid breaking small bits (feedrates, stepover, etc.)

    3). I haven't quantified it yet, but I have some suspicions that there's some backlash in the motion system. It might be minimal, but it could affect small parts. Even then, I think you can compensate for this by only climb cutting when milling.

    4). I've kept my buildplate hot during milling operations, but I also milled structures larger than your gears. Maybe using a raft would work too. Additionally, this blog post from Diabase shows how they milled a part, removed it from the buildplate and set it into a fixture (also printed) to do a final engrave on the part surface. I imagine you could do the same with a simple fixture for your gears. The nice thing is that everything, including the fixture can be designed and accounted for in F360 Design & Manufacturing.

    https://www.diabasemachines.com/post/addition-and-or-subtraction

    The video at the bottom of the page shows how they use a hot roller to finish TPU parts
     
  2. Greg Holloway

    Greg Holloway Administrator
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    Smallest end mill I have used is 2mm. You can go just about any size you like, but the smaller the end mill the higher the RPM you'll need.
     
  3. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    With your small BLDC motor and the belt speed reduction, what RPM range are you seeing at the tool? I have seen plastic melt when a saw blade or drill is cutting too quickly. (is that why you are showing milled PEEK?)
     
  4. Paul Arden

    Paul Arden Well-Known Member

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  5. Greg Holloway

    Greg Holloway Administrator
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    According to an RPM counter we are around 10k-10.5k rpm.
     
  6. Greg Holloway

    Greg Holloway Administrator
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    If you have any feedback for the plug-in create an issue on the GitHub. Andy is very responsive and will add things in for you.
     
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  7. Paul Arden

    Paul Arden Well-Known Member

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    Looks like that materials list has been expanded in the meantime (though most of them saying they don’t really work yet, so still ASA and PEEK being the best), however there is more detail about cut in, speeds etc now as well. Well worth turning on Github notifications for the repository to watch the changes being made.
     
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