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Thread: New to CNC

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  1. #1

    Join Date
    Aug 2019
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    New to CNC

    I just bought a bobs cnc machine and built it. It's up and running. I wanted to know where I start on this journey to learn cnc machining. The machine is for wood and hard plastics. I have cut some things but I am at a loss when it comes to knowing what settings to put into easel for speeds and depth of cuts. I don't know what sounds are not good when running the machine and what good milling sounds like. It came with a Dewalt 660.

    Any information is appreciated I hope to learn a lot here.

  2. #2
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    Apr 2016
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    797

    Re: New to CNC

    Take a look at GWizard. You'll find it here: https://www.cnccookbook.com I was in your boat three years ago. GWizard helped (and continues to help) me with feeds & speeds. They offer a free trial.

    Gary

  3. #3
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    Re: New to CNC

    First thing, think of your first project, something you can do with templates and a router.
    Been doing this too long

  4. #4
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    Re: New to CNC

    Quote Originally Posted by bostosh View Post
    First thing, think of your first project, something you can do with templates and a router.
    Interesting advice. Thinking back some 45 years, I spent a lot of money replacing and sharpening bits, because of premature wear. With the right feeds and speeds my bits last much longer. The wrong feeds and speeds can either break bits, or wear them out real fast. With a CNC, it is much easier to control for quality of cut and maximum bit life than with handheld routers and templates, or with routers mounted under a table. I still use my 9 or 10 routers now and then, but only for that odd job where creating models and toolpaths takes more time than just picking up a router, or using my router table. Unfortunately, I still wear out bits faster than when using my CNC.

    Point is, there can be a big difference between what is possible to do, and what is best to do. Thinking back to my manual router days provides me with little insight into the best feeds and speeds for my CNC.

    Gary

  5. #5

    Join Date
    Jun 2018
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    325

    Re: New to CNC

    Feeds and speeds, materials and choice of bits.

    Then there's RPM on the bit, how many cutting edges and the material the bit is made out of. The cheaper bits (often steel body with carbide cutting edges) are not generally intended to be machine driven (relentless and constant motions). I've found on the smaller bits (3 mm cut), the cutter shank can bend and then the cut width is more like 3.something_bigger). The machine rigidity also plays an important role WRT vibration - often causing bit wear/breakage and trashed parts. Clamping of material is very important too.

    A good helper is a directed compressed air stream at the bit into the cut path. This helps keep the bit cool and avoids re-cutting the chips - extending tool life and providing a better finish.

    Quite a bit of trial and error to find the "sweet spots" for your machine but a good trap is to cut too slowly at too low an RPM for fear of breaking bits. Also being a "hog" can break bits quickly too. Again a bit of practice like you did with the hand tools.

    If you find test files in the wild watch out for speeds, feeds, rapids and measurement systems (inch, metric) and that the drawings fit within your machine boundaries.

    A full depth cut might only be practical on a finishing pass, too shallow and the tip wears quickly.

    Sorry, not much to say about what might work or not for your machine - it depends.

    Like welding, the "right" sounds are learned as the quality improves (and the bits don't break :-).

    Have fun but stay safe! :-)

  6. #6
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    Join Date
    Oct 2019
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    Quote Originally Posted by he1957 View Post
    Feeds and speeds, materials and choice of bits.

    Then there's RPM on the bit, how many cutting edges and the material the bit is made out of. The cheaper bits (often steel body with carbide cutting edges) are not generally intended to be machine driven (relentless and constant motions). I've found on the smaller bits (3 mm cut), the cutter shank can bend and then the cut width is more like 3.something_bigger). The machine rigidity also plays an important role WRT vibration - often causing bit wear/breakage and trashed parts. Clamping of material is very important too.

    A good helper is a directed compressed air stream at the bit into the cut path. This helps keep the bit cool and avoids re-cutting the chips - extending tool life and providing a better finish.

    Quite a bit of trial xender discord omegle and error to find the "sweet spots" for your machine but a good trap is to cut too slowly at too low an RPM for fear of breaking bits. Also being a "hog" can break bits quickly too. Again a bit of practice like you did with the hand tools.

    If you find test files in the wild watch out for speeds, feeds, rapids and measurement systems (inch, metric) and that the drawings fit within your machine boundaries.

    A full depth cut might only be practical on a finishing pass, too shallow and the tip wears quickly.

    Sorry, not much to say about what might work or not for your machine - it depends.

    Like welding, the "right" sounds are learned as the quality improves (and the bits don't break :-).

    Have fun but stay safe! :-)
    It came with a Dewalt 660.
    Last edited by liyary; 11-03-2019 at 02:34 AM.

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