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  • roughing endmill question

    Do roughing endmills use the same speed and feed formulas as regular endmills or is there a different set.
    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

  • #2
    Use the same speed. Over speed will burn the cutting edge ruining the cutter.

    Feed can usually be increased, but if increased too much you get chipping of the cutting edge which will ruin the cutter.

    Main reason for roughing cutters is to lighten the load because of low HP and not ridged machines. You can remove material quickly, but you need to change cutters for a finished surface.

    Bob

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    • #3
      I also have a similar question, what about using speeds/feeds that are to slow? I am talking about, for example 20% to 30% slower than recommended? Does this hurt anything besides production rates? Might sound like a dumb question but I have heard different opinions on this.

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      • #4
        Quoted Speeds and feeds are for use in production modes were time is money.

        In a home shop going slower saves the cutter (many home shop machines can't handle full size S & P anyway) but takes longer, just don't try and force a cutter, at a lower RPM, to go through the metal at the same speed as if it was going at the higher RPM's. Lower speed, lower feed.
        The shortest distance between two points is a circle of infinite diameter.

        Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

        Southwestern Ontario. Canada

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        • #5
          Hobby machinist here so take what I say with a grain of salt. The more enlightened here can correct me on this, but I believe that feeding too slow can dull milling cutters prematurely. If I am not mistaken the premature dulling is due to rubbing rather than cutting. Speeds (RPMs) that are too high can also dull cutters due to overheating their cutting edges. There is a happy medium of feed and speed where production and cutter life are both greatest.

          Professionals feel free to chime in on this please.
          Last edited by firbikrhd1; 11-17-2011, 01:48 PM.

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          • #6
            Lower SFM's save cutter life, Less tip heat/friction/etc.
            Lower feed rates *reduce* cutter life, Because to remove the same amount of material, you need to cut that many more times..

            Of course, too high a feed rate chips a cutter.

            So basicly, if your cutters get dull, Feed rate is too slow, If your cutters chip, Feed rate is too fast.

            Lower SFM = lower production speed but longer tool life. Harder the metal, the lower the SFM you'll want to start at, I don't think theres any bottom limit on SFM, except when you consider that some (Carbide mainly..) tooling may produce a really poor surface finish at lower SFM.

            And yea, Roughers let you take much DEEPER passes without the excessive chattering and hammering a non roughing cutter would result in. You don't want to incress the SFM past what you would use a finishing cutter of the same material on, But you can greatly improve the depth of cut and width of cut without as scary of a hammering sound since all the little 'fingers' engage gradualy and at diffrent times. Sorta like it has more flutes, as well as taking a deeper cut lets it engage more of the flute at once.
            Last edited by Black_Moons; 11-17-2011, 02:37 PM.
            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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            • #7
              I'm no expert and never was employed in the field, so this is just one opinion.

              I like to cut with a roughing mill, turning the handle by hand. It seems like I can get a good "feel" of how much is being cut. Usually use slower speeds, but cut quite a chunk with a nice solid feeling feed rate.
              VitŮŽria, Brazil

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              • #8
                Roughing

                That is quite possibly the best way to go about it.
                Kansas City area

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