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  • Roughing end mill

    Hi, im wondering, how does one use a roughing end mill? Yes I know sounds like a stupid question, but my real question is really: What does one incress when using a roughing end mill as compaired to a standard smooth end mill?

    Depth of cut? Feed rate? or SFM? (Or just chip load per tooth?)

    Can they be used for deeper sloting or endmilling cuts too? or just deeper side milling?
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

  • #2
    I don't do a lot of hogging, but I use mine for slotting & profiling. You gain FPR, smaller more easily handled swarf and deeper DOC and length of flute engagment. DON'T ever run one in climb milling on a manual machine, they are very "grabby" and will yank the table around.

    I use roughers whenever I have to remove a large volume of material prior to a finishing cut, the dovetail in QC tool holders for my KDK is a prime example along with roughing out the slots for the turning tools.

    Good roughers are expensive, but they will save you a pile of time to get material hogged out so you can dedicate your valuble time to finishing parts, not roughing them out.
    Ignorance is curable through education.

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    • #3
      Here are two of my "roughers" - aka "Corncobs".



      From memory they are about 20mm (~0.800") and 10mm (~ 3/8") with a plain spiral-fluted end mill - about 12mm (~ 1/2") for scale.

      They do cut very well - higher feed rates and depths and lengths of cuts - but over-loading or over-speeding will ruin them. So slow the speed down and use plenty of coolant (aka "suds") or cutting oil - WD40 or paraffin for aluminium.

      I never plunge cut as I prefer to drill first and use a smaller end mill. Same with slotting - one side at a time - after I open the slot with a smaller end mill - although I prefer to drill as many holes as possible first as I have only got to go from hole to hole and not end to end of a slot in one go.

      Slotting in one go is the maximum you can load a cutter up to at any depth. The cutter tends to rub and climb mill - not pretty. If slotting in one go and it does not penetrate the job the prior-cut slot behind the cutter will accumulate swarf and and may jamb the cutter.

      Roughers are one of the hardest tools to get right on a tool & cutter grinder as the "inside" of the flute (the "top face") has to be ground where-as a conventional end mill is sharpened by grinding the "outside" of the cutter.

      It is possibler to "gash" a rougher on a tool & cutter grinder or even a pedestal grinder with a hand-formed "saucer" wheel (Aluminium Oxide - "white" - wheel) by hand. The T&C grinder is better but neither method is as good as new.

      Roughing cutter finishes are not all that bad most times so I leave them "as is" unless a "better" finish is a "must".

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      • #4
        Originally posted by Black_Moons
        What does one incress when using a roughing end mill as compaired to a standard smooth end mill?
        The user shouldn't increase anything, not at first. They're meant to be used with similar parameters to finishing endmills. They're a lot smoother running in heavy cuts - things you'd normally not be able to do on a smaller mill become possible.

        They decrease force by taking a larger chip load per flute. If you have a proper rougher, each of those teeth will have a clear shot (or nearly clear shot) at the metal for the entire circumference of the tool.

        So a three flute rougher being fed at .005 per tooth will really have a .010-.015 chip load.

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        • #5
          Originally posted by toastydeath
          They decrease force by taking a larger chip load per flute.
          Yep, it is simply easier to remove material with a rougher, especially on small HSM mills.

          I use roughers as much as possible, and only use a standard mill when a better finish is required.

          There is also such a thing as a "fine" roughing mill, with lots of little teeth instead of a few big teeth. I use a 3/4" fine rougher for a particular finish operation. It is easier on the 6x20 than a standard mill, and the finish is satisfactory as-is.

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          • #6
            Intresting. how about those 'finishing' roughers?
            the kind that insted of a wavy (sine) tooth pattren, its a more square tooth pattren.
            Advantages/disadvantages to those?
            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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            • #7
              Roughing endmills will take a cut the full length of the mill in a pass to cut a slot at a faster rpm and feed than a standard endmill. You do have to use a mist coolant system to get the chips out of the slot, flood coolant or oil will not work there.

              You can take a full length full width of the roughing endmill as a side cut on the work with little trouble at faster rpm and feed than any other endmill. I use them to cut a large hole in plates where sawing is hard to do. Most the time I can rough it out faster than I could bandsaw it if I have to cut and weld the blade.

              The drawback is they leave a rough finish so you have to leave metal to finish out with a standard endmill.

              If you have to remove metal fast using an endmill there is nothing better than the roughing endmills and a coolant mist is the best with them.
              Last edited by Carld; 08-18-2009, 08:51 PM.
              It's only ink and paper

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              • #8
                Ok so my only question remaining is should I bother with coatings for my rougher if im gonna do aluminum or steel?
                Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                • #9
                  Coatings probably don't matter for home use...... Mine has chinese yellow pixie dust (allegedly TiN coating) on it, but that doesn't stop it working....

                  I noticed that I could cut as fast as I could crank, 5/8" deep, with it, in CRS. MUCH better than with standard end mills.

                  The finish isn't that bad... some lines, but looks much like a shaper or planer finish.......... OK on many surfaces.
                  1601

                  Keep eye on ball.
                  Hashim Khan

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