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Cutting aluminum dry

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  • Cutting aluminum dry

    Howdy from Florida,

    I'm trying to build my first CNC machine, mostly from 80/20 aluminum and aluminum flat stock. It is a 10'x8' hotwire foam cutter capable of cutting two blocks of foam at once.(hopefully will be) I have built my controller housed in an outdoor solar power box and have it running in Mach3 with 425 in/oz steppers. My linear guides are made of cold rolled steel with 90‌ degree bevels, to accommodate the Bishop-Wisecarver type V bearings. I designed all of my aluminum parts in the Aspire program and just need to get them cut. Here are some photos.

    I cut my first parts, the "cars" which the y axis rides on, out of .5'' aluminum flat stock, with a single flute, solid carbide router bit, supposedly made for aluminum. It cut those rwo parts pretty well with the Shopbot set on 75''/min with the router running at 10,000 rpm. But on the third part, the bit gummed up with aluminum and started trashing the cut. I hit the panic button and quit. maybe I was running it too slow? or the bit dulled or something. So I tried a 4p-flute solid carbide and the aluminum basically melted to it doing a profile cut on the first part. This is the first bit I used to cut the .5'' aluminum

    and this is the second.

    Today I tried the 4/fluted bit at 18''/min @ 10,000rpm, spraying with the foaming thread-cutting lubricant while it was routing. It cut OK but it was messy. Until I get a milling machine, all I have is the router and my slowest spindle speed is 10k RPM. Does anyone know what is the best xy speeds and pass depth for doing this "dry" with the single flute? What about cooling it with air as it cuts?

    Last edited by 3Dsigns; 02-24-2015, 06:53 PM.

  • #2
    Dry isn't going to work at 10,000 rpm. It heats up the alum. too much. A 4 flute endmill is not good for alum. either. Use a 2 flute end mill and some TapMagic for Aluminum. Use a shallow depth of cut, maybe .050 per pass at 60"/minute. Adjust up or down from there. Put some TapMagic where the cut goes, then a little in the groove made by the cutter for each pass. It only takes a little but makes all the difference.
    Kansas City area


    • #3
      Thanks so much, Toolguy! Found some...


      • #4
        You also need to remove the chips as they are being created. Use compressed air blowing on the bit continuously and use WD40 every couple of seconds to help lubricate the bit.


        • #5


          • #6
            This is the stuff I tried this afternoon. Will this get me by until get some of the tapmagic?
            Last edited by 3Dsigns; 02-24-2015, 11:27 PM.


            • #7
              WD40 is recommended for cutting aluminum.


              • #8
                Get a Koolmist unit, that will do what you need for a long time. Or better yet one of the pressurized systems like the bijur or trico systems.

                Don't use a 4 flute for aluminum, 3 flute at the most on larger cutters and 2 on smaller. I like the carbide for-aluminum cutters from Lake Shore Carbide.

                No matter what, you need some sort of cutting fluid for aluminum. Cutting dry will plug up the cutter in any decent cut that will utilize your cutter. WD40 does work but it is expensive and works no better than a synthetic coolant like Trico TC1 (What I use) and it water soluble so cleanup is a breeze. Plus no lingering smells. A gallon of TC1 will make up to 40 gallons of coolant. Thats $1 gallon vs $20 a gallon for wd-40.


                • #9
                  Wow! thanks so much for the help!


                  • #10
                    Name of the game here is getting rid of the heat. In a perfect world, the chip will carry all of the heat away, leaving the material cool. The more cutting surfaces you employ, the more heat is generated. I cut AL on my router table (I have a "somewhat" variable speed router - it still doesn't get all that slow, like 6-12 K rpm) and I use a single flute bit called an 'O' bit, like shown here. As others have said, use some kind of fluid for lube as well as heat conduction, keep the DOC within reason, and keep the swarf clear of the tool path.

                    Also, keep the swarf away from the air inlet on the router! (Or so I've been told.... )
                    Last edited by revwarguy; 02-25-2015, 07:04 PM.


                    • #11
                      Thanks! I was going to try some of the suggestions this afternoon, but either the VGA card or the monitor failed on my puter. Have to get that fixed before I do anything now.


                      • #12
                        I got to thinking; I used to do sandblasted signs and there is a cooling unit, sandblasters put in series with their air supplies, called a "Vortex Tube". Has anyone tried one for cooling cutters on a router? This one seems to be adapted for that.


                        • #13
                          Originally posted by revwarguy View Post
                          Name of the game here is getting rid of the heat. In a perfect world, the chip will carry all of the heat away, leaving the material cool. The more cutting surfaces you employ, the more heat is generated.
                          Exactly.. Heat.. Either go slow and don't build HEAT(not an option here), or get the HEAT out... Weather that be with coolant, or toss it with the chip...

                          How do you get the heat out with the chip... BIG FATTY chip... And make sure it gets out of there, and not recut.

                          If you kept the same 75ipm feed with the 4 fluter, that gives you less than .002" chip thickness... You gummed up the single fluter at
                          .0075" of chip..... Feed it HARD...

                          I didn't believe that you could cut aluminum (6061) dry, but you can... Here is a little vid of my first attempt at running dry.. 1" 2 fluter, 7000rpms,
                          and 250ipm... Or 1850sfm, and .018" per tooth... Not a particularly efficient tool path, but I had saved so much time already, I didn't care.


                          • #14
                            I use a router all the time. I have a speed controller I use to cut aluminum with it. Dials it down to a reasonable speed and dry cutting aluminum plate or sheet is no problem. I did a bit of trial and error to get mine dialed in but, once you do that, its easy.
                            Makes aluminum step plates for trucks.

                            And cutting out fan openings in aluminum sheet for custom radiator and trans cooler shrouds.



                            • #15

                              What RPM, bit, bit size, feed rate did you use?