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brushless DC motors for mini lathes

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  • brushless DC motors for mini lathes

    I need a new motor for my Boley Leinen 8mm lathe and my web searches have led me to thinking brushless DC motors have very good characteristics for mini lathes. Is anyone here using one on their lathes and if so, what brand?
    Thanks,
    henryr

  • #2
    From the model airplane motors and speed controls I've used I would suggest that the speed controller you use is as important or perhaps more important than the motor.

    On some they start and run very smoothly even at super low RPM while others sound pretty much like gravel filled gearboxes. But once up to something like 10 to 15% power/speed the ones I've used all smoothed out and run very smoothly. And given that they have very little torque when running that slow anyway it's likely not an issue other than having to listen to the raspy sounding starts each time you start and stop the motor....

    Price of the controller, at least in my cases, has not been a good guide of this "feature" being present or not. I'm talking about the ones for use with RC systems now. Not those in a box with a speed control dial.

    The odd thing is that I can point you at any number of motors that would give you enough power and which are about the size of a walnut. Or to be fair and allow for derating for cooling purposes the size of a lemon and only about 5 oz. But because they have holes in the end bells and need air and have strong permanent magnets they would need shielding from any ferrous swarf. And due to that lightness they don't have the most suitable of bearings for a good long life in an application like you're after. Mind you they are cheap. $36 for THIS ONE
    Chilliwack BC, Canada

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    • #3
      Wasn't sewing machine "servo" motors quite popular option for tiny lathes?
      IE something like this https://www.ebay.com/itm/Sewing-Mach...UAAOSw1ABd7Vmr
      "seving servo" should bring you plenty of results from ebay.
      Location: Helsinki, Finland, Europe

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      • #4
        https://www.youtube.com/watch?v=Vnev...hannel=MarkusK.

        Seem to have enough power even for bigger than 8mm watchmakers lathes.
        Location: Helsinki, Finland, Europe

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        • #5
          https://www.amazon.com/Genuine-CSM10...6350993&sr=8-5

          More than enough power for a mini lathe. I'm using one for an overhead drive on a rose engine.

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          • #6
            I've used a few of them and like them. You can't beat the low end torque from a servo - it just keeps putting more current to to maintain a constant speed. The complaints with the consew motor are 1) that the speed is in steps, i.e. not analogue...200 rpm increments and 2) reversing it is a pita, requires a bunch of button pushes. (2) mostly doesn't matter, but I have one little lathe that threads where I need it.

            For a watchmakers lathe its pretty much a requirement that you have foot control. They work well for that in that the OEM speed control is a lever. you can mount it under the bench, run the rod straight down fromt he lever then have a piece of something go from the rod to the ground at say a 5 or 10 degrees - makes a great foot pedal. I also hacked mine to get a pot speed control but still haven't done the hack for a convenient reverse switch.

            Use a bit of care if hacking the electronics. The speed control electronics are only 5V, but they're at like 165 to 160V over earth ground. 🙄
            Last edited by Mcgyver; 03-24-2021, 05:23 AM.
            in Toronto Ontario - where are you?

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            • #7
              Those are very good motors but 3/4 hp is too much. I need 1/4 hp or less.

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              • #8
                Originally posted by henryr View Post
                Those are very good motors but 3/4 hp is too much. I need 1/4 hp or less.
                why? any safety aspect is addressed by belt slipping.

                besides, those are based on the much smaller Chinese horses.

                The challenge is getting a reasonable amount of torque at low speeds and at such a reasonable price point. This motor addresses that, DC motors (unless a servo) do not.
                in Toronto Ontario - where are you?

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                • #9
                  I'm in Connecticut USA and I'm gonna check out specs of that 3/4 hp motor.

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                  • #10
                    that was my initial reaction as well, huge over kill - most original watchmakers lathes had 1/10 hp. But they are under powered at slow speed and running at slower speed is helpful for some things (imo) and I couldn't think of reason why not to use the consew.
                    \
                    I wouldn't say you just have to have it vs the traditional motor, but I've found it a good option. I also it set up sort of station I can plunk different lathes in front of including a unimat 3 for which it is a nice upgrade (notoriously under powered)
                    Last edited by Mcgyver; 03-21-2021, 07:38 PM.
                    in Toronto Ontario - where are you?

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                    • #11
                      I never have had problems with a small old motor made for the lathe type. It might even be 1/10 HP, or less. But I don't have a case chuck, and I do not use the machine for things the size of cases and bezels, where it is possible that there would be more of an issue.
                      2730

                      Keep eye on ball.
                      Hashim Khan

                      Everything not impossible is compulsory

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                      • #12
                        I'm rather thinking that if a foot pedal was used for the speed control that controlling the speed would become pretty automatic.

                        Henry, what have you used up to now? I'm seeing a lot of 100 to 150 watt rated regular sewing machine motors that come as a kit with a matched speed control. Granted they are not brushless but any time I'm using my old black Singer one stitch fits all for something it seems pretty easy to modulate. And when the belt is off the motor it runs very smoothly. Any shake, rattle and roll is either in the machine or the operator.
                        Chilliwack BC, Canada

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                        • #13
                          I've been using an Emesco 90N 22,000 RPM ac motor and it is much to fast and has low torque at low RPMs. And I've recently learned that many of the commercial sewing machine motors are brushless DC servo motors but all I found are 3/4 HP. But there are many companies making brushless DC servo motors from less than 1/10 hp to very high horsepower and all, but China made, very are expensive. Click image for larger version

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                          • #14
                            You should check the brushless motors used on electric skate boards. They're not so high speed as the RC types and have good torque.
                            Helder Ferreira
                            Setubal, Portugal

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                            • #15
                              Originally posted by henryr View Post
                              I need a new motor for my Boley Leinen 8mm lathe and my web searches have led me to thinking brushless DC motors have very good characteristics for mini lathes. Is anyone here using one on their lathes and if so, what brand?
                              Thanks,
                              henryr
                              Huh...

                              Brushed, brushless... Same thing, same motor.. I love a good DC motor. Figure it out.
                              I am looking for a solid 3.0-3.5kw motor.

                              Problem? Off the shelf power supply,,,


                              I cant find one and I dont want to build one.


                              JR

                              Edit: I am sorry Henryr..

                              I screwed the pooch on that post. So sorry... JR
                              Last edited by JRouche; 03-26-2021, 01:18 AM.
                              My old yahoo group. Bridgeport Mill Group

                              https://groups.yahoo.com/neo/groups/...port_mill/info

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