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Re: [mill_drill] new article available: A Variable Frequency Drive plus Three Phase Motor on a RF30 Mill/Drill

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  • Brian Bayorgeon
    This is all very interesting and timely to me. I am in the process of a complete tear down and rebuild of a 30 year old Taiwanese ram head mill that I am
    Message 1 of 37 , Jun 22, 2011
    This is all very interesting and timely to me.  I am in the process of a complete tear down and "rebuild" of a 30 year old Taiwanese ram head mill that I am re-powering to loose the 575 volt 3-phase 2 speed motor that came with.  I am going with a 2hp 230 VAC 3 phase motor that I just purchased, I'm currently researching VFDs, PLCs, and touch screen interfaces.  One thing I plan to do is put a sensor on the spindle and have a digital read out of spindle speed and possibly close loop control of spindle speed. (I know, probably not needed)

    One of my big concerns was the resulting speed capability and obtaining an effective speed range / capability.  I hoping for a 100 to 4000+ Hz spindle range.

    I have also made up a spreadsheet that users may be interested in checking out, I will attach it if i can.

    Overall keep the comments coming, I am absorbing it all and will apply accordingly on my current project.

    thanks

    Brian
  • Rick Sparber
    Dan, Running 400 RPM means 400/60 = 20/3 or almost 7 times the rated motor RPM. That is huge. The vendor said 2 times rated is ok but I was hoping they would
    Message 37 of 37 , Jun 23, 2011
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      Dan,

      Running 400 RPM means 400/60 = 20/3 or almost 7 times the rated motor RPM. That is huge. The vendor said 2 times rated is ok but I was hoping they would bless 3 times. 

      Rick

      On Jun 23, 2011, at 8:22 AM, "Dan Mauch" <dmauch@...> wrote:

      Good. The metal shield should work as a good blast shield.  All kidding aside the reason for my comment is that I have heard  guys running VFD at 400 Hz on machines that weren’t designed for that. Usually it was the ones with the gearhead mill/drills .

       The pulleys are the weak spot because of the keyway and the usual sharp  corners at the bottom of the keyway which make them subject to possible cracking over time. The centrifugal forces are substantial at spindle speeds of 4000 RPM. Steel pulleys may be more prone to cracking in the keyway because they are usually more brittle than aluminum.

       

      www.camtronics-cnc.com

      dmauch@...

      Stepper and servo motors

      Kits, assembled and custom CNC using Gecko products.

       

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