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  • Milling Machine Help

    I admit that I am self taught and that means learning the hard way by making mistakes.

    Why can't I get smooth surfaces with my milling machine? It is a Grizzly clone of an Ron Fu. Here are some photos.


    5/8" 4 flute sharp end mill in a 5/8" R8 collet. Minimum quill extension, Quill lock tightened, 650 spindle rpm, depth of cut .0025", horizontal feed is slow, power feed, 2 hp 3 phase motor


    I can detect no vertical movement in the quill when it is locked measuring with a dial indicator and trying to lift it with a wood lever.
    Another photo


    What causes the circles?

    Any help appreciated.
    Peter
    Grantham, New Hampshire

  • #2
    Your RPM is good. Your DOC is fine.

    Looking at the circles, I see different sized circles. Did you do multiple passes with different sized end mills?

    Swirls are normal when using the end of the endmill to cut metal. I see you have more pronounced rings at some spots. That's more common when you pause while hand feeding. Did you use lube, and did you clear the chips as you cut?

    The good news is that it looks like your mill is trammed well.

    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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    • #3
      Originally posted by danlb View Post
      Your RPM is good. Your DOC is fine.

      Looking at the circles, I see different sized circles. Did you do multiple passes with different sized end mills?

      Same end mill for all cuts and same DOC. Quill stayed locked. No lube and not clearing chips.

      Is the debris causing the problem? The mill is trammed dead on both X & Y axis. Power feed all passes.

      Swirls are normal when using the end of the endmill to cut metal. I see you have more pronounced rings at some spots. That's more common when you pause while hand feeding. Did you use lube, and did you clear the chips as you cut?

      The good news is that it looks like your mill is trammed well.

      Dan
      Same end mill for all cuts and same DOC. Quill stayed locked. No lube and not clearing chips. Power feed. Is the debris causing the problem?
      Peter
      Grantham, New Hampshire

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      • #4
        What material is it?
        www.thecogwheel.net

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        • #5
          Not seeing any photos.......
          CNC machines only go through the motions

          Comment


          • #6
            I can't see your pictures so no idea, but make sure you're NOT CLIMB milling. If your machine has any backlash which I'm sure it does, climb milling can cause all kinds of problems. Make sure your pushing the table into the cutter and the cutter is pushing back, not grabbing and pulling the table in the same direction your feeding. Make sure you're standard milling. If you have ball screws or very low backlash it's not really a problem but you definitely should only be standard milling:

            Comment


            • #7
              Originally posted by CPeter View Post
              Here are some photos.
              I see no photos.

              Which Ron Fu?

              Using my not-so-rigid and not-so-fast 6x26, end mills give me a swirly finish. The only way I can get a mirror finish is using a 3" face mill.

              The grown-up CNC mills produce a mirror finish by running at very high speeds.

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              • #8
                ALL mills give a scalloped finish when milling with the side of the cutter. The work moves as the cutters cut, and the cutters are turning, so the surface is not "knife cut".

                When cutting with the end , or face mills, the feed vs the cutter corner radius makes a difference, but you nearly always get some "swirly" marks, even if they may be just "visible" and not of any significant depth.
                CNC machines only go through the motions

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                • #9
                  I can't see the pictures either.
                  Location: Long Island, N.Y.

                  Comment


                  • #10
                    I can see the photos and I am on a different computer than I used to post them. Another 'puter problem to figure out.

                    The answer may be the clime cutting. I did this in three passes and the center was climb cut. That really makes sense. The material is hot rolled steel, but I get the same think with cold rolled. I usually get a lot of my steel at the local steel supplier's cut off area. Sometimes it is really great and sometimes not as good.

                    I will try the same piece with all standard cutting.

                    Thank you
                    Peter
                    Grantham, New Hampshire

                    Comment


                    • #11
                      Looking at the source for this page I see your pictures are coming from something called lh3.googleusercontent.com. After logging into my gmail
                      account I refreshed this page and had placeholders show up for the pictures but the pictures themselves were still not visible.
                      Location: Long Island, N.Y.

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                      • #12
                        No pics... tech suppooooooooort!

                        Loose vise, loose table, loose knee, wonky bearings, bad tram.....

                        Make sure you are not getting material buildup on cutter edges. lube if need be.. wd40 for Al...

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                        • #13
                          Climb cutting won't make a difference on .0025" DOC. I can't see the pictures either but some swirl is normal. Deep swirls could be caused by an improperly sharpened tool or the mill head isn't trammed to the table.

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                          • #14
                            Pics are now circles with dashes in them. It knows there are supposed to be pics now, they just ain't there.
                            CNC machines only go through the motions

                            Comment


                            • #15
                              Swirls are normal as mentioned already. But if your swirl marks are inconsistent for depth you may be picking up metal on the cutter lip which gouges in deeper and then chips away. That leaves you with some swirl marks deeper than others. In which case a cutter lube will help. As would lightly blowing the chips away as they form.

                              Let's put it this way. A little sanding should clear the swirl marks away and leave you with a sanded surface. If you have some deeper swirls that persist then you have galling of metal onto the cutter to deal with. A cutting lube should fix that by stopping the metal chips from heat and pressure bonding to the cutter.

                              I've also found that I get a smoother surface if I feed the table fast enough to get proper chips instead of something more like dust. With a DOC of only .0025 it'll be harder to tell but even there the chips should be little "C" shapes or little figure 9's.

                              Another thought is to try a flycutter. For those of us wanting more of a nice looking surface the flycutter can do a nice job. If your mill is not dead on tram though you get a flatter surface from multiple passes with a smaller end mill.
                              Chilliwack BC, Canada

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