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  • #46
    Originally posted by Tincamp01 View Post
    I hesitate to say I am untrained. On a different forum a few years ago, I was basically snubbed when I mentioned that.

    Aren’t sewing machine motors kinda small? Never thought about that as an option. The beast currently on my lathe is the size of a gallon milk jug.
    Hahaa. I have no doubt you know what you are doing.. Sewing machine motor? I wouldnt. I think they are ac/dc motors also, no torque really.. That big gallon sized motor you have is probably a legit US motor with legit HP rate. Id stay in that lane. Let us know. Id like to hear if you go VFD. I would like to on mine but my single phase works still. JR

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    • #47
      You'll spend more experimenting with cheaper setups when you finally determine you should of went with VFD. You aren't the first.

      Comment


      • #48
        There are sewing machines and then there are SEWING MACHINES!! The machines he was referring to are industrial sewing machines and not the one your grandmother had. They have a built in clutch and lots of torque. I have one that will go through 3/8" of leather and it is treadle powered, but it had an electric motor option, but the treadle is easier to use for me.
        Grantham, New Hampshire

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        • #49
          Originally posted by RB211 View Post
          You'll spend more experimenting with cheaper setups when you finally determine you should of went with VFD. You aren't the first.
          This.
          Especially when there are 120v 1ph to 230v 3ph VFDs so cheap.
          Look at AutomationDirect.com

          -Doozer
          DZER

          Comment


          • #50
            I've got multiple spindle motors on machines running on VFDs. Its intimidating at first, but once you get some basics going its not that big of a deal. I even have one 120V 1ph in to 220V 3ph out running a 1hp 24000 rpm spindle. I bought that VFD from Drives Warehouse. I don't know how they compare for price, but when I thought I had an issue I left them a message and maybe 15 minutes later a guy called me from home on a Saturday night to help me walk through a setup that would work for my application.

            Most less expensive VFDs are NOT rated for full power on single phase input. If running a 2/3HP motor then get a 1HP VFD. The rule of thumb is to derate by about 30-35%, but you can get away with less if you never max the motor. I have a 5HP Leland running on a 5hp VFD thats on single phase. I calculate all the cuts at 3HP or less and haven't had any issues. When I hose it up all that happens is the overload triggers on the VFD and I have to open the cabinet and reset it.

            On a lathe I would definitely make sure to get a VFD rated 30-40% higher than the motor you choose if running 1 phase in and 3 phase out.

            Now before somebody comes along and corrects me. Yes I know there are VFDs whose published rating is for single phase input. Polyspede is one. (not a misspelling.)
            *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

            Comment


            • #51
              Originally posted by RB211 View Post
              You'll spend more experimenting with cheaper setups when you finally determine you should of went with VFD. You aren't the first.
              The major advantages of a VFD are well known...... well balanced 3 phase, and variable speed.

              The major advantages of an RPC are different. What it does is simply provide 3 phase, in very much the same way as the power company. What that does, is make any 3 phase machine a "plug and play" installation. If the voltage is right, the machine will run. And one RPC can run any machine in the shop, by simply turning on the machine. Depending on the power capability, it can run 2 or 3 or more machines.

              Yes, I know, and can intelligently discuss, the differences between powerco 3 phase and RPC 3 phase. Those differences are not huge, and need not be a problem.

              The other side of the issue is "what are the disadvantages?".

              For a VFD, the first disadvantage is that one VFD can run one machine only. You cannot use one VFD with more than one machine, unless you simply use it as a converter, and ignore the variable speed feature. And if you do that you need a MUCH larger VFD. Buying a lot of VFDs can run to some serious cash, even though they are each reasonably low cost.

              The second issue with a VFD, is that essentially, you have to tear out the controls in the machine, they cannot be used with a VFD. You may be able to salvage a few switches, but the rest is of no use. You are on your own to re-wire the machine to operate with the VFD.

              The third issue is for machines that have more than one motor. One VFD cannot run all the motors, unless, as before, it is considerably larger, AND you do not want to use variable speed. If there is a coolant pump, or an axis feed, you are on your own to figure out what to do about those, as the VFD can only run the spindle. You need another VFD for the next motor, etc, etc. (Or you can make some sort of static converter, etc to run each other motor.)

              For the RPC, the disadvantage is basically that you do not get variable speed.

              All the controls work fine, and any feed or pump motors will work fine. If the machine has a mechanical speed variation, that will work fine. It is "plug and play". All you need to do is provide an RPC that handles the total power you want at one time, meaning the ratings of the motors or machines you want to run at one time.

              So, to decide what you are going to do, ignore ALL the people who tell you what THEY would do. THEY are not YOU. It's easy for them to tell you what to do, and how to spend YOUR money.

              Look at what you want to do.

              If you just want to run the machine, or machines, then an RPC is probably the least trouble, as it is plug and play, with no modifications, re-wiring, etc. And the RPC can power any other 3 phase machines you have, or get, if it has sufficient power capability to handle those that will be run at once.

              If you just gotta have variable speed, then you need a VFD for each machine you want to run. And you need to make all the modifications and re-wiring necessary, on each machine that you want to run

              I have never seen a pressing need for that in my shop, so I do not have any VFDs, just one RPC. You may be different.
              CNC machines only go through the motions

              Comment


              • #52
                Originally posted by J Tiers View Post

                The major advantages of a VFD are well known...... well balanced 3 phase, and variable speed.

                The major advantages of an RPC are different. What it does is simply provide 3 phase, in very much the same way as the power company. What that does, is make any 3 phase machine a "plug and play" installation. If the voltage is right, the machine will run. And one RPC can run any machine in the shop, by simply turning on the machine. Depending on the power capability, it can run 2 or 3 or more machines.

                Yes, I know, and can intelligently discuss, the differences between powerco 3 phase and RPC 3 phase. Those differences are not huge, and need not be a problem.

                The other side of the issue is "what are the disadvantages?".

                For a VFD, the first disadvantage is that one VFD can run one machine only. You cannot use one VFD with more than one machine, unless you simply use it as a converter, and ignore the variable speed feature. And if you do that you need a MUCH larger VFD. Buying a lot of VFDs can run to some serious cash, even though they are each reasonably low cost.

                The second issue with a VFD, is that essentially, you have to tear out the controls in the machine, they cannot be used with a VFD. You may be able to salvage a few switches, but the rest is of no use. You are on your own to re-wire the machine to operate with the VFD.

                The third issue is for machines that have more than one motor. One VFD cannot run all the motors, unless, as before, it is considerably larger, AND you do not want to use variable speed. If there is a coolant pump, or an axis feed, you are on your own to figure out what to do about those, as the VFD can only run the spindle. You need another VFD for the next motor, etc, etc. (Or you can make some sort of static converter, etc to run each other motor.)

                For the RPC, the disadvantage is basically that you do not get variable speed.

                All the controls work fine, and any feed or pump motors will work fine. If the machine has a mechanical speed variation, that will work fine. It is "plug and play". All you need to do is provide an RPC that handles the total power you want at one time, meaning the ratings of the motors or machines you want to run at one time.

                So, to decide what you are going to do, ignore ALL the people who tell you what THEY would do. THEY are not YOU. It's easy for them to tell you what to do, and how to spend YOUR money.

                Look at what you want to do.

                If you just want to run the machine, or machines, then an RPC is probably the least trouble, as it is plug and play, with no modifications, re-wiring, etc. And the RPC can power any other 3 phase machines you have, or get, if it has sufficient power capability to handle those that will be run at once.

                If you just gotta have variable speed, then you need a VFD for each machine you want to run. And you need to make all the modifications and re-wiring necessary, on each machine that you want to run

                I have never seen a pressing need for that in my shop, so I do not have any VFDs, just one RPC. You may be different.
                Yep, I have both an RPC and many VFD's.

                Comment


                • #53
                  Originally posted by J Tiers View Post

                  The major advantages of a VFD are well known...... well balanced 3 phase, and variable speed.
                  .......
                  I have never seen a pressing need for that in my shop, so I do not have any VFDs, just one RPC. You may be different.
                  The discussion is replacing a SB lathe motor.
                  It was submitted that a 3ph motor and a VFD
                  offered numerous advantages over 1ph.
                  No one is considering converting the SB lathe
                  to 3ph and then running an RPC. That's crazy.
                  Just another opportunity for you to talk about
                  how great you think RPCs are ? ? ? ? ? ? ? ?

                  -D
                  DZER

                  Comment


                  • #54
                    Originally posted by Doozer View Post

                    The discussion is replacing a SB lathe motor.
                    It was submitted that a 3ph motor and a VFD
                    offered numerous advantages over 1ph.
                    No one is considering converting the SB lathe
                    to 3ph and then running an RPC. That's crazy.
                    Just another opportunity for you to talk about
                    how great you think RPCs are ? ? ? ? ? ? ? ?

                    -D

                    Well, Doozie-boy, so far, 17 of the 40 the posts (including yours) have mentioned and generally recommended using VFD and 3 phase. Posts 2, 4, 6, 7, 9, 10, 11, 15, 16, 19, 20, 22, 23, 36, 40, 47, and 49.

                    Now, perhaps you disagree, but an idea that has come up, with enthusiastic recommendations, in almost half the posts in the thread, seems pretty damn relevant. It needed some clarification as to what ways it can be done.

                    BTW, 3 phase is 200% better, whether done with a VFD or an RPC. I converted a single phase machine to 3 phase, and put in an RPC.... because it was a lot better as 3 phase. I did not do it for variable speed, which is pretty good for some things, but did not seem needed for the lathe. Still doesn't, there isn't anything I have run into that having it would do better.

                    Yes, I chose an RPC because I figure to install some more 3 phase machines.

                    Go back under the bridge, stop being a troll.
                    Last edited by J Tiers; 05-01-2022, 10:06 PM.
                    CNC machines only go through the motions

                    Comment


                    • #55
                      Only reason I have an RPC was for the 10EE. Going to gut the old system and put a big servo spindle drive in it. Only my surface grinder uses the RPC. That should have a VFD on it as well

                      Comment


                      • #56
                        Originally posted by JRouche View Post

                        Hahaa. I have no doubt you know what you are doing.. Sewing machine motor? I wouldnt. I think they are ac/dc motors also, no torque really.. That big gallon sized motor you have is probably a legit US motor with legit HP rate. Id stay in that lane. Let us know. Id like to hear if you go VFD. I would like to on mine but my single phase works still. JR
                        Jees'em Get with it

                        https://www.consew.com/View/Consew-Clutch-Motors

                        Comment


                        • #57
                          Originally posted by CalM View Post
                          The speed control on those if you want to interface to them, sends line voltage on the wires to the pot. You need to isolate it for CNC control. Maybe not an issue for this. Buy then from Amazon, they sometimes come with a bad speed control.

                          Comment


                          • #58
                            Originally posted by RB211 View Post

                            The speed control on those if you want to interface to them, sends line voltage on the wires to the pot. You need to isolate it for CNC control. Maybe not an issue for this. Buy then from Amazon, they sometimes come with a bad speed control.
                            There is no speed control with a single phase induction motor. That is what the step pulley in the head stock is for.

                            A 3ph clutch motor driven by a VFD would be cat's meow.

                            Myself, I would take the clutch motor over the variable Frequency drive in a South Bend application.

                            Comment


                            • #59
                              Here is a project for building a single phase VFD, although I think it would be much better to use a PIC:

                              https://www.homemade-circuits.com/si...equency-drive/

                              Here is a company that sells single phase input and output VFDs from 1/2 HP to 10 HP:

                              https://www.ato.com/single-phase-vfd
                              http://pauleschoen.com/pix/PM08_P76_P54.png
                              Paul , P S Technology, Inc. and MrTibbs
                              USA Maryland 21030

                              Comment


                              • #60
                                Originally posted by PStechPaul View Post
                                Here is a project for building a single phase VFD, although I think it would be much better to use a PIC:

                                https://www.homemade-circuits.com/si...equency-drive/
                                Use at your own risk: "I have not tested it yet, but everything looks correct to me in the design…" (the designer)

                                Here is a company that sells single phase input and output VFDs from 1/2 HP to 10 HP:

                                https://www.ato.com/single-phase-vfd
                                What!?! There goes a central tenet of my understanding of single phase motors: they cannot be operated very far outside their native frequency. I always believed that there was something inherent in their design that made them unsuitable for VFD use. That they overheated and/or lost power and/or something or other. What's the real story?

                                Does this mean that all those conversions that I made to 3-phase motors were unnecessary & I could have just used single-phase output VFD's?

                                BTW - those VFD's are 220v output.

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