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Re: [mill_drill] Max spindle speed

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  • Dan Mauch
    Good thinking. The problem that most guys overlook when trying top run at high speeds is that the heavy pulley wasn t designed for that much centrificul force.
    Message 1 of 7 , Apr 30 6:57 PM
      Good thinking. The problem that most guys overlook when trying top run at high speeds is that the heavy pulley wasn't designed for that much centrificul force. Hate to see a piece of pulley hit you in the face as it comes apart
      Dan Mauch
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      ----- Original Message -----
      From: wrz2000
      Sent: Thursday, April 30, 2009 5:45 PM
      Subject: [mill_drill] Max spindle speed

      Dear All,

      I have a VFD installed on my mill (similar model of mill to the one on the front page here). Currently I have limited the maximium speed to 3,000 rpm. I would like to be able to run it up to 10,000rpm but I am not sure if this is a good idea.

      Thanks

      Warren

    • Jerry
      you are kidding, correct? Does your VFD even go to 300hz? I ran mine at 3000rpm a lot of hours without a problem. I would say you have to loosen your preload
      Message 2 of 7 , May 1, 2009
        you are kidding, correct? Does your VFD even go to 300hz?

        I ran mine at 3000rpm a lot of hours without a problem. I would say you have to loosen your preload nut about 10 turns go get to 10k :~)

        I have a Sherline mill with the 10k conversion pulleys that runs all day at 10k but I loosened the preload a little on that headstock.

        the bearings are not that expensive so give it a try. Better yet, get a cheap set of SKF bearings from NAPA auto and put them in first.

        Also, set your overload current so it drops as soon as it gets over normal running current and you probably wont damage much. You do not want the bearings to freeze and turn on the shaft. You will need a cutting torch if that happens.

        Jerry


        --- In mill_drill@yahoogroups.com, "wrz2000" <groups@...> wrote:
        >
        > Dear All,
        >
        > I have a VFD installed on my mill (similar model of mill to the one on the front page here). Currently I have limited the maximium speed to 3,000 rpm. I would like to be able to run it up to 10,000rpm but I am not sure if this is a good idea.
        >
        > Thanks
        >
        > Warren
        >
      • Phil Teague
        ... Warren, this is not a good idea. Using grease in the bearings, the tapered roller bearings in your mill (30206 and 30207) are good for maybe 4,500 rpm as I
        Message 3 of 7 , May 1, 2009
          --- In mill_drill@yahoogroups.com, "wrz2000" <groups@...> wrote:
          >
          > Dear All,
          >
          > I have a VFD installed on my mill (similar model of mill to the one on the front page here). Currently I have limited the maximium speed to 3,000 rpm. I would like to be able to run it up to 10,000rpm but I am not sure if this is a good idea.
          >
          > Thanks
          >
          > Warren
          >
          Warren, this is not a good idea.

          Using grease in the bearings, the tapered roller bearings in your mill (30206 and 30207) are good for maybe 4,500 rpm as I recall from reading a bearing manufacturer's website. However, I wouldn't spin my mill that fast, at least not while I am in the same room with the mill. Like Dan says, the cast iron pulley would probably go before you got anywhere near 10k.

          These mills are just not designed to go that fast. Would you consider running a lathe that was designed to go 1550 rpm (like most of the 12 x 36 lathes) at 8-10K rpm? I hope not.
        • cnc4cheap
          Warren, You are talking about some serious spindle speed. You might want to consider using an overdrive attachment. C4C
          Message 4 of 7 , May 1, 2009
            Warren,

            You are talking about some serious spindle speed. You might want to consider using an overdrive attachment.

            C4C

            --- In mill_drill@yahoogroups.com, "Phil Teague" <philteague@...> wrote:
            >
            > --- In mill_drill@yahoogroups.com, "wrz2000" <groups@> wrote:
            > >
            > > Dear All,
            > >
            > > I have a VFD installed on my mill (similar model of mill to the one on the front page here). Currently I have limited the maximium speed to 3,000 rpm. I would like to be able to run it up to 10,000rpm but I am not sure if this is a good idea.
            > >
            > > Thanks
            > >
            > > Warren
            > >
            > Warren, this is not a good idea.
            >
            > Using grease in the bearings, the tapered roller bearings in your mill (30206 and 30207) are good for maybe 4,500 rpm as I recall from reading a bearing manufacturer's website. However, I wouldn't spin my mill that fast, at least not while I am in the same room with the mill. Like Dan says, the cast iron pulley would probably go before you got anywhere near 10k.
            >
            > These mills are just not designed to go that fast. Would you consider running a lathe that was designed to go 1550 rpm (like most of the 12 x 36 lathes) at 8-10K rpm? I hope not.
            >
          • leasingham_connelly
            Replacing the original single phase motor with a 3 phase/VFD on my machine increased the spindle speed (at mains frequency on the VFD)by a factor of 2.2. By
            Message 5 of 7 , May 2, 2009
              Replacing the original single phase motor with a 3 phase/VFD on my machine increased the spindle speed (at mains frequency on the VFD)by a factor of 2.2. By doubling mains frequency this gives a 4.4 increase of spindle speed. So as the chart on the pulley cover gives top speeds of 2080 and 2500 (for 50Hz and 60Hz) 9000 to 10000 rpm is easily achievable but not necessarily a good idea. I have aluminium pulleys not cast iron but it could still be more revs than is good for them. I think you can dial out resonant frequencies with the VFD so vibration may not be too big an issue. I tend to use my mill with the belts in one position with a top speed of 830 rpm (VFD at 100Hz) which suits nearly everything I do. I have never felt the need for speed when machining as it is a hobby not a business for me. Mostly steel, some brass, some aluminum alloy.

              Martin

              --- In mill_drill@yahoogroups.com, "Jerry" <jehancoc@...> wrote:
              >
              > you are kidding, correct? Does your VFD even go to 300hz?
              >
              > I ran mine at 3000rpm a lot of hours without a problem. I would say you have to loosen your preload nut about 10 turns go get to 10k :~)
              >
              > I have a Sherline mill with the 10k conversion pulleys that runs all day at 10k but I loosened the preload a little on that headstock.
              >
              > the bearings are not that expensive so give it a try. Better yet, get a cheap set of SKF bearings from NAPA auto and put them in first.
              >
              > Also, set your overload current so it drops as soon as it gets over normal running current and you probably wont damage much. You do not want the bearings to freeze and turn on the shaft. You will need a cutting torch if that happens.
              >
              > Jerry
              >
              >
              > --- In mill_drill@yahoogroups.com, "wrz2000" <groups@> wrote:
              > >
              > > Dear All,
              > >
              > > I have a VFD installed on my mill (similar model of mill to the one on the front page here). Currently I have limited the maximium speed to 3,000 rpm. I would like to be able to run it up to 10,000rpm but I am not sure if this is a good idea.
              > >
              > > Thanks
              > >
              > > Warren
              > >
              >
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