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Questions about Rockwell Mill

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  • Questions about Rockwell Mill

    I started another thread asking about a reversing switch for my new (to me) Rockwell mill. After thinking about it and doing a little research I have a few more questions.

    The mill is a combination vertical and horizontal one. The motor for the vertical is a 1/2hp, 1phase.

    The motor for the horizontal is 1 1/2hp, 3 phase (I think), labeled 230v 460v, but no indication that it is indeed a 3 phase motor. Incidentally, the fellow I bought it from said the horizontal motor didn't work. The machine has a static converter on it.

    My first question is that I am wondering of the need to reverse the motor in the vertical, if I don't need to reverse the motor, then why get a reversing switch?

    Second question is how large a motor is required for the horizontal mill? Would a 1/2hp be enough, or how much power is needed? I ask because it may be more sensible to change the horizontal motor to a single phase.

    Thanks, Dennis

  • #2
    Use a VFD with it as it is likely 3 phase. If you cant tell for sure which phase it is, post a pic of the wiring coming out of the motor and we will help I say keep it 3 phase, as 3 phase has many advantages to single phase. With the VFD, even machines that arent variable speed (as in not step pulleys) become it at the touch of a button. If youre sure that you dont need reverse, dont bother with a reversing switch. Personally I would rather have capability rather than not.

    Is it a horizontal with a vertical head added (one with its own motor) or is it a pure horizontal with a verticle attachment powered off the spindle? If its the latter, dont let anyone convince you that its not a great mill, those type are.

    Hope everythings good in Anchorage, I miss AK. I spent 4 years of my military time in Fairbanks and loved it.
    "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."


    • #3
      I have a Rockwell H/V model also, with the 1 1/2hp motor on the horizontal. When I first got it, I experimented with a half hp DC motor and it was actually quite adequate for most uses. If you intend to use large slab cutters, obviously you will need more power. As far as the vertical, I guess if all your cutters work in the proper direction you may not need the reverse, but it is nice to have. Have fun! Rob.


      • #4
        I'm not sure if my mill is a horizontal with a vertical attachment, but it wouldn't surprise me, The vertical head and motor come off in one large heavy piece.

        I'm pretty sure the motor for the horizontal can be changed to about any type, but the vertical motor has a mounting flange that looks like it is specific to the machine (maybe not specific).

        What is a VFD? Is it a variable speed controller for a 3 phase motor? I can see where having a variable speed motor would be great for cutter speed. I've seen other threads where people have used a treadmill motor for a variable speed drive. I haven't looked into that at all, but maybe it is a possibility.



        • #5
          VFD = Variable Frequency Drive. Many (BUT NOT ALL!!!) take single phase power input and give you three phase output. They have the advantage (their main function) of also giving you variable speed which is extremely nice when it comes to finding the sweet spot when cutting. Im currently finishing up installing one on my Bridgeport. For less than the cost of a new 1 hp motor (<$100), I get my choice of 110 or 220 single phase input, smoother operation than a single phase motor, and the ability to instantly reverse motor function. Mine also has a host of other functions, my favorite of which is programming the acceleration and braking of the motor, which I hope will make the head bearings/gearing last longer. With one VFD, you should be able to wire in both motors, assuming you dont use both simultaneously.

          Now that Im done sounding like a commercial...please post us a few pictures if you get the opportunity. We all love good tool porn, and I personally love helping others whenever I can with their machines.
          "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."


          • #6
            The mill, base and table are all the same on horizontal and the vertical models. 21-122 is the combo machine. Mine came with a 3/4 hp vert. motor and 1.5 hp horizontal motor. IIRC, that is the factory configuration. I'll dble check that when I get home. The vertical motor has an extra long shaft 4-3/32"(???) so replacement can get $$$ quickly unless you luck out.

            I run mine on an RPC but would recommend a VFD as the slowest vertical speed on a 1725 rpm motor is 370 rpm. This inhibits some boring slitting saw ops in steel, but overall is a well built mill. A 1140 rpm option gave the slowest speed as 245 rpm.

            I'll check manual to see about all the motor choices.

            On edit: the factory horizontal motor recommendations called out a 1 or 1.5 hp constant speed motor, single or 3 phase, 1725 rpm 182 frame.
            Last edited by recoilless; 03-24-2011, 10:01 PM.
            I bury my work


            • #7

              You have a PM.
              I don't do drugs.
              At my age, I can get the same effect if I stand up too quick!