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Fastest way to remove aluminum with a mini mill?

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  • Fastest way to remove aluminum with a mini mill?

    I'm starting a couple of projects, and I could use some advice. I have a LMS 3990, and I'm milling 6061 aluminum.

    What size and type of end mill would I use to "hog" material, before finishing?

    Larger would be better? A roughing end mill, I assume?

  • #2
    3/8" 3 flute coarse roughing end mill would be the best bet. Going larger won't necessarily increase metal removal rate.

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    • #3
      Well, you start with the published specifications for the mill. From the LMS web site, the max tooling should be:
      End Milling Capacity 0.6" (16 mm)
      Face Milling Capacity 1.2" (30 mm)
      Drilling Capacity 0.5" (13 mm)

      So given that, it comes down to a question of what shapes you are trying to mill. A frequent technique for making deep pockets is to use a drill bit to remove most of the metal, and then clean it up with an endmill. So you'd use a 1/2 inch drill to make the area look like swiss cheese, then follow up with a 1/2 or 5/8 endmill.

      On the other hand, if you need to remove 1 inch from the side of a long piece of 2 inch thick metal, you will probably find that a 5/8 inch roughing end mill (AKA corn cob) will remove a lot of metal fast and leave surface that is easy to clean up with a normal end mill.

      On the third hand, if you are needing to simply smooth off the top of the work, a 1-1/4 inch face mill will do the trick without overtaxing the mill.

      Dan
      At the end of the project, there is a profound difference between spare parts and left over parts.

      Location: SF East Bay.

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      • #4
        Depends, what are you "hogging" off? Taking out the bulk of a 3/4"x3/4" slot, taking 1/4" off the top of a block, what? Ive got the grizzly version of that machine, and for roughing i grab different tools for different uses. If i need to rough out that slot, for example, im probably just going to reach for a sharp 1/4" end mill. I can bury it at nearly full depth, rough out the material, then use the same tool for finishing. Taking 1/4" off the top of a block though, im just going to grab my 2 inch face mill, go for it in 3 depth passes and be done with it. A roughing end mill might be able to do the entire thing in 1 depth pass, but then you throw in the side to side passes and tool change for a finishing tool and the facemill is just faster.

        I do like roughing end mills though, i just dont use them in every roughing case. If i were taking 1/2" off the side of a bar of 2 inch stock or cutting a ledge, a rougher would be my first choice, but again, it all depends on the use case and subsequent tool changes needed

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        • #5
          I haven't got an alu specific roughing endmill but I am running an SX2 mill (albeit with solid column conversion)which is probably fairly similar to what you're talking about. In steel very recently I was getting bad chatter with an 8mm carbide end mill with a radiused end at 0.5mm DoC. Switched to a 10mm HSS fine rougher and was able to do a good 6.5mm DoC without chatter. The roughers definitely make a big difference.
          my 4-flutes may not be ideal for alu though.
          The 2-flute carbide aluminium profile endmills are probably better for surface finish and chip clearance there.

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          • #6
            Drilling is the fastest way to remove stock. Drill away the waste, then clean up with a two flute end mill.

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            • #7
              Fastest way to remove aluminum with a mini mill?


              Loosen clamps, hold downs, or vise. Lift or crane aluminum from table.

              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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              • #8
                Originally posted by CalM View Post
                Drilling is the fastest way to remove stock. Drill away the waste, then clean up with a two flute end mill.
                Yes indeed, but I will say it another way...
                Plunge cutting is the fastest way to remove metal on a vertical mill.
                This is because the mill is MOST RIGID in the vertical axis (Z axis).
                The vertical mill architecture is a letter C, like a C clamp.
                Forces should spread a C clamp, not twist it.
                Milling X or Y directions is twist. Not rigid.
                So put the most force in the Z direction
                for the least chatter and the most available cutting pressure.
                --Doozer
                DZER

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                • #9
                  If you have one, a band saw if the best way I have found to remove a lot of material fast. Cut oversize and finish on the mill.

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                  • #10
                    No one mentioned a belt sander?
                    Mass is king on a milling machine for removing metal.
                    My vote is also a rougher endmill.

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                    • #11
                      The way I heard it.

                      If it's just stock you need moved, use a hack saw
                      if you need to hold dimensions, use a machine tool.

                      I follow that principle whenever fabrication is being done. Saves on consumables..... ;-)

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                      • #12
                        Originally posted by RB211 View Post
                        No one mentioned a belt sander?
                        Too many bad memories trying to hog off aluminium with a belt grinder...

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                        • #13
                          I like Bobs method- I was thinking along similar lines. My idea was to mount a fly cutter- and don't bolt the aluminum down. Feed aggressively- guaranteed that aluminum will be removed from the mill in short order.

                          But on a serious note, I'm hearing a lot about roughing end mills. I don't have any, but I'm going to buy some. It just makes sense that it would work well.
                          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                          • #14
                            Start with an amp meter and use a rougher. You want to use all the HP available, which immediately says motor at 100% speed, whether using high range or low range gear if you have it. Pick the tool that matches that spindle speed in aluminum and use the amp meter to adjust depth of cut and feed rate to use maximum amps. Note that passing the tool through the material the least number of times increases tool life and removal rate. So a deep depth of cut that requires a slow feed will not be optimum. Roughers are smooth running and produce tiny chips that are easily blown out of the toolpath to avoid recutting. My first experience with a rougher was machining 304 stainless and I was amazed at how fast it was.

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                            • #15
                              I like that running up to max power PROVIDED the machine itself does not start complaining by chattering.

                              On lighter machines I too found that it is often better to go to a smaller size and use more of the cutter. I also need to buy some roughing end mills and try them out. The promise of better chip control and resulting deeper feed per flute has a nice sound to it.
                              Chilliwack BC, Canada

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