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Bought 3/4hp 3phase motor by mistake, what to do with it

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  • Bought 3/4hp 3phase motor by mistake, what to do with it

    Other than a door stop what can I use this thing for? rotary phase converter?(I know nothing about the subject matter)

  • #2
    Buy a VFD and you have great motor for most anything.

    Hal

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    • #3
      Buy a phase convertor to go with it and carry on. A teco convertor will cost about $120.00, and you will NOT be sorry.
      Duffy, Gatineau, Quebec

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      • #4
        I vote for the VFD (it will cost you about $100). Put the motor on your drill press and you can plug the VFD into a 115V wall outlet. Here's a link:

        http://dealerselectric.com/item.asp?cID=28&PID=1104

        You will kiss the ground I walk on for making this suggestion.
        Last edited by Forrest Addy; 09-13-2011, 11:10 PM.

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        • #5
          Would it be worthwhile to put one of these on a 9x20 lathe, to replace the 3/4 horse that is on there now?

          Dan
          At the end of the project, there is a profound difference between spare parts and extra parts.

          Location: SF East Bay.

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          • #6
            Originally posted by danlb
            Would it be worthwhile to put one of these on a 9x20 lathe, to replace the 3/4 horse that is on there now?

            Dan
            Hell yes, but you might be happier with a little more HP.

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            • #7
              You just can't beat a VFD on a lathe.....

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              • #8
                Originally posted by Forrest Addy
                I vote for the VFD (it will cost you about $100). Put the motor on your drill press and you can plug the VFD into a 115V wall outlet. Here's a link:

                http://dealerselectric.com/item.asp?cID=28&PID=1104

                You will kiss the ground I walk on for making this suggestion.
                Well, hello...

                Do those work alright on 110, 15-amp circuits? And do they have a 115 -> 220 single-phase?
                Last edited by Deus Machina; 09-14-2011, 07:53 AM.

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                • #9
                  Make your own rotary phase converter

                  I used a small 3-phase motor to build my own rotary phase converter so I can run a larger HP 3-phase motor on my lathe. Your 3/4 HP just might be just the ticket to do something like that.
                  Bill

                  Being ROAD KILL on the Information Super Highway and Electronically Challenged really SUCKS!!

                  Every problem can be solved through the proper application of explosives, duct tape, teflon, WD-40, or any combo of the aforementioned items.

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                  • #10
                    use more than 3/4 HP on a 9 x 20?

                    OOOOOOKAAAAAYYYYY

                    Seems like that is enough to take two turns and a half hitch on the bed of a 9 x 20.

                    I have a 1/3 HP on a 10" Logan , and have NEVER had any limitation from the motor whatsoever. And I KNOW that machine can stand a larger motor just fine.

                    JT


                    Originally posted by BigBoy1
                    I used a small 3-phase motor to build my own rotary phase converter so I can run a larger HP 3-phase motor on my lathe. Your 3/4 HP just might be just the ticket to do something like that.
                    The usual rule is the reverse..... A 1 HP RPC for a half horse load, 2HP for 1 HP load, etc.

                    I am not sure how you have the "small" RPC set up to start the "larger" motor on the lathe. if it works, I guess it works, but...
                    1601

                    Keep eye on ball.
                    Hashim Khan

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                    • #11
                      My 13" swing LeBlond came with a 3/4 HP motor.
                      (Though maybe that was to limit damage as it was originally supplied to a high school)
                      "Patriotism is the last refuge of a scoundrel"

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                      • #12
                        3/4 hp on a vfd will only give 3/4 hp around it's nominal frequency of 60hz. At say 30hz, you'll get about 3/8 hp..

                        If it worries you (shouldn't) then just set the VFD motor current so that it can only get 1/2 hp out.


                        Yes, you can buy a VFD that runs from 120v, BUT... it won't run on a typicial GFCI (if that bothers you). There is no "fault" - just the vfd noise currents being filtered to ground inside the vfd.

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                        • #13
                          Originally posted by BigBoy1
                          I used a small 3-phase motor to build my own rotary phase converter so I can run a larger HP 3-phase motor on my lathe. Your 3/4 HP just might be just the ticket to do something like that.

                          This sounds like a better use for my little motor. Please elaborate? What was the hp of your rpc and hp of the lathe motor? and what the max hp the rpc can drive?

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                          • #14
                            dvo. I don't think I'm overselling when I suggest you research the VFD ad get some referrals. You havve a several speeds on a lathe, mill, drill whatever. The variable speed feature of the VFD fills in between - an important thing when you need lower speeds than you can gear for.

                            You may wish to avoid what seems like complication but installing a VFD is no more complex than building a phase converter.

                            I'm sure a few will chime in with VFD testimonials. I have four on my machine tools.
                            Last edited by Forrest Addy; 09-14-2011, 06:35 PM.

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                            • #15
                              Send it to me

                              Actually Forrest's suggestion is an excellent one. I replaced the 1 hp Taiwanese motor on my 30 year old Grizzly mill with a 3/4 hp 3 phase 1725 rpm motor. It is so sweet. The VFD was just over $100. It will drive a 1 hp 3 phase 220 volt motor while being fed by 120 volt single phase power. It has a surprising amount of torque at low speeds as the VFD can push more current to the motor in an attempt to maintain the speed setting. Reversing is very easy. I love not having to change belt positions to get correct speeds. I can run 3/16" to 1/2" drills with good results, even larger if I take it easy. I would never go back to the single phase motor.

                              I don't believe a rotary phase converter based on a 3/4 motor can safely run a 3 phase motor larger than itself. I thought that typically if you wanted to run a 3 hp 3 phase motor, that you needed a rotary converter based on a 5 hp motor.

                              gordon
                              Last edited by ironnut; 09-14-2011, 07:33 PM.

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