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  • CNC Programing

    This may not be the place to ask this, but the folks over at that CNC forum seem rather snobish. Don't care to get flamed for asking a seemingly stupid question. When programing a CNC machine to operate do you have to enter in the feed and speed and doc or do you just tell it the material you are machining and it will use optimum configurations?

    I hope this isn't a really stoopid question, but I have been wondering this for a while.

    Patrick

  • #2
    You usually have to manually enter the feed and speed.

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    • #3
      There are too many variables for the programmer to anticpate to accurately calculate feed and speed. To begin it not only depends on the material type but the alloy, the cutter type and material, number of flutes, spindle rpm and the machine charateristics and wear. The setup, tool overhang and holder type, tool wear and the phase of the moon also matter.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Mach3 has a "wizard" available that helps you calculate proper feed and speed and chip load for various materials, but you have to enter information about the cutter type, diameter, and material. Maybe a couple other details. Even then, a test run may indicate that the speed and feed ought to be modified a bit.
        ----------
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        • #5
          And, the rigidity of the machine..

          A bridgeport without the swivel head is much more rigid than one with all the knuckles and gear train that adjusts cutter angles.

          during cuts, I could feel my bridgeport come under stress and off by laying my hand on the mill head.
          Excuse me, I farted.

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          • #6
            My CAM system prompts you for the material type, cutter type and if coolant will be used and calculates the speeds and feeds. I can also input speeds and feeds into the tool path manually. I can aslo go into the tool and material libraries and make SFPM modifications if I don't like what the system is outputting.
            Mark Hockett

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            • #7
              You enter speed and feed,doc is programmed when you tell the tool to go to the start of the cut.There is a cnc control which has a lot of data entered for material,tool types,speeds,feeds etc,but it`s the exception rather than the rule.

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              • #8
                Originally posted by Mark McGrath
                There is a cnc control which has a lot of data entered for material,tool types,speeds,feeds etc, but it`s the exception rather than the rule.
                Most modern (Fanuc, Anilam, ...) CNC controllers are like that now: the speeds and feeds are calculated by the CAM program (they're basically looking up the tables in Machinery's Handbook), but there are speeds and feeds dials on the controller itself that you can use to override the CAM software.

                The dials at the bottom of this Fanuc controller are the speeds and feeds overrides:

                Last edited by lazlo; 01-12-2009, 01:40 PM.
                "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                • #9
                  By the way Patrick, the CNC forum of PracticalMachinist is probably not the right place to ask these kind of questions, but CNCZone is a huge forum populated by a young and vibrant crowd of amateur CNC enthusiasts.

                  They're very good about answering questions like this, and there are a ton of FAQ's (Frequently Asked Questions) about steppers versus servos, acme versus ballscrews, linear versus dovetail ways, ...

                  Here's the CNCZone sub-forum that's dedicated for CNC FAQ's:

                  http://www.cnczone.com/forums/forumdisplay.php?f=172

                  If you go to the Gallery section, there are literally hundreds of home-built CNC machines, ranging from CNC routers, mills, gantrys, lathes, Bridgeport retrofits...

                  http://www.cnczone.com/gallery/showgallery.php/cat/505

                  You'll see a lot of familiar faces over there, including McGyver, S_J_H, Sir John, CKelloug, ...
                  Last edited by lazlo; 01-12-2009, 01:52 PM.
                  "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                  • #10
                    If you don't like picking feeds you buy one of the high end CNC controls. Program the tool path and tell the control the accuracy to the tool path you want to maintain. The machine then goes like hell while trying to maintain the tool path within your accuracy spec.

                    Sorry for the smart ass reply, but as least it gives guys something to lust for when they get beyond Mach 3.

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                    • #11
                      "Most modern (Fanuc, Anilam, ...) CNC controllers are like that now: the speeds and feeds are calculated by the CAM program (they're basically looking up the tables in Machinery's Handbook), but there are speeds and feeds dials on the controller itself that you can use to override the CAM software."

                      Since when was a cam programme part of a cnc control?

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                      • #12
                        I've seen a few high-end controls with a CAD/CAM package built in. Great for doing online edits.

                        The 1990s vintage WARCOM pressbrake I used to run had a CAM system of sorts, you'd draw the part on screen, tell it where to bend and what material/thickness and it would program itself. Use of anything other than WARCOM supplied tooling would often result in tears and scrap until someone went in and changed the tables.
                        This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.
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                        • #13
                          "I've seen a few high-end controls with a CAD/CAM package built in. Great for doing online edits. "

                          Apart from a 20 year old type specific cnc,would you like to name anymore?
                          I`m thinking Fanuc,Siemens,Heidenhain.What I would call industry standard names.

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                          • #14
                            Well I seem to remember the AMADA Promecam brake having something similar, and I know for a fact the Amada NT controller had it as well. These are industry-standard as far as I am concerned bad spelling aside.

                            Now if I'm not mistaken the laser at VI MFG was refit with a controller that had an online cad/code generator program, and I know for a fact the mills did as well. I want to say Hurco but as I did very little milling there (mostly press-work) I can't be certain. I remember one of the machinist-programmers drawing a quick fixture for me on the machine controller itself, pressing a few buttons handing me the results before lunch.
                            This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.
                            Heirs of an old war/that's what we've become Inheriting troubles I'm mentally numb
                            Plastic Operators Dot Com

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                            • #15
                              I agree that most cnc laser,plasma,pressbrake and punch machines have some kind of cam programme built in.But these are basic programmes and unless you spend $000`s basic is what you get.I have a cnc punch and a cnc pressbrake and by no stretch of the imagination can you call the canned cycles the manufacturer gives you cam.They are also not mainstream machines in the machining sense and the op asked about feed,speed and doc which means metalcutting machines in the line of lathes and mills.

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