Electric motor size (physical)

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  • Quetico Bob
    Senior Member
    • Apr 2008
    • 350

    Electric motor size (physical)

    Anyone ever tried to google electric motors for a small frame (body) size….sigh.

    What I need, I think is a 1/10 to 1/8 hp 120V ac motor with a small frame say between 2” – 3” diameter. The “I think” part is based on a 60watt DC/90V motor which the calculators, again by google suggest close to1/10hp. But I don’t know if I am comparing apples to apples.

    Heck the first hit I got for calculating watts to HP wanted to know my height, weight and so on to find out how much HP it would take for me to climb a set of stairs….? Not only that, they want you to run up them. Nothing like inducing a heart attack to perform what I thought would be an easy calculation.

    Anyway, what I’m hoping, is some of you can point in the right direction for a model number that would at least get me in the right area (category). Tried the big name suppliers web sites but again…sigh. Everything I looked at was full size motors and there is just to many to pull the specs on each. Thinking, GE, Baldor, Leeson probably a few more, but these pop to mind.

    This way on my next trip to the city I can order at the not so local supplier and pick up when it eventually shows.

    Heck, I’d even look at sewing machine motors if I could find out who made them.

    It would be nice to find a small sealed unit with the fins cast on the outer body just because it would make a cool looking piece of equipment, but not a necessity. Saw one of these once on an electric chainsaw sharpener, yup, googled that to…sigh.

    Cheers, Bob
  • lazlo
    Senior Member
    • Jun 2006
    • 15631

    #2
    Originally posted by Quetico Bob
    What I need, I think is a 1/10 to 1/8 hp 120V ac motor with a small frame say between 2” – 3” diameter. The “I think” part is based on a 60watt DC/90V motor which the calculators, again by google suggest close to1/10hp.
    Baldor and Bodine makes a whole line of AC and DC fractional horsepower motors and gear motors in that size. The Bodine A24 series, for example.

    I don't think there is any kind of standard form factor in that size, which would explain why you're not finding them on a Google search.
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

    Comment

    • Evan
      Senior Member
      • May 2003
      • 41977

      #3
      A dc motor with a 3 inch can is much more likely to be around 1/2 hp to 1 hp or so while an ac induction motor the same size is probably closer to 1/10 hp. Especially in the small sizes DC motors are much more powerful than induction motors. They don't require much or even any iron depending on type and have a lot more flexibility in torque and speed range. A lot of small tools have gone to dc permanent magnet motors including low end compressors, chain saws and lawn mowers.
      Free software for calculating bolt circles and similar: Click Here

      Comment

      • lazlo
        Senior Member
        • Jun 2006
        • 15631

        #4
        Originally posted by Evan
        A dc motor with a 3 inch can is much more likely to be around 1/2 hp to 1 hp or so
        Those are little Chinese horses Evan. A quality Bodine DC motor with a 3 inch can is about 1/8 HP.

        I have a 3/4 HP Baldor DC motor I retrofitted on my drill press, and it's about 35 lbs, and about 8" in diameter:
        Product Overview: CDP3443


        Those treadmill motors you get from SurplusCenter aren't even close to their nameplate power. Like Sears Craftsman horses
        Last edited by lazlo; 06-11-2009, 02:32 PM.
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

        Comment

        • Pherdie
          Senior Member
          • Jan 2003
          • 736

          #5
          I'm on the same quest, 1/6 to 1/4 hp , 115 VAC motor, to complete a project.

          Compounding my issue is a desire for a 3250 rpm in a foot mount, split phase configuration. They're out there, Bodine (as mentioned) seemingly has the best selection in this category. Real pricey though and nothing on the surplus/used market so far. I'm considering purchasing a $69.00 Harbor Freight belt sander and removing the motor. I'll just work around the C mount....

          Fred

          Comment

          • Quetico Bob
            Senior Member
            • Apr 2008
            • 350

            #6
            Whoa Whoa Whoa.

            Before you two get into a pissing match, me first. Can both of you confirm the HP calculation and what I now think is the form factor size I’m looking for. Then you can let her rip. One thing, if you don’t play nice, I’m talking both the balls and sandbox time away.

            Cheers, Bob

            Comment

            • lazlo
              Senior Member
              • Jun 2006
              • 15631

              #7
              Originally posted by Quetico Bob
              Can both of you confirm the HP calculation and what I now think is the form factor size I’m looking for.
              Your calculation is correct: a 60 Watt motor is 60/746 = .080 ~= 1/12 HP.

              The problem is that there are lies, damn, lies, and horsepower ratings. A quality motor has a horsepower rating spec'd for operating horsepower including a service factor. In other words, a 1/12 HP NEMA motor will run for thousands of hours at 1/12 HP, and at intermittent duty run at substantially higher HP.

              Import motors are (in)famous for specifying stall current: the locked-rotor current when the motor stalls, which is a useless rating, but looks better on paper. My 7x10 Mini-Lathe is a great example: the spindle motor is the size of a soup can, and it's "rated" as 3/4 HP. But you can stall it by grabbing the spindle.

              The "real" 3/4 HP Baldor DC motor that I posted above, which is about 10 times the weight and volume, will rip your arm off if you tried that...
              Last edited by lazlo; 06-11-2009, 03:31 PM.
              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

              Comment

              • Quetico Bob
                Senior Member
                • Apr 2008
                • 350

                #8
                Quote” The problem is that there are lies “ Quote Man I wish someone would tell me how to put a proper quote in.

                I assumed those “lies” would be there and thank you for reinforcing it. My Bridgeport puts it in black and white (nothing to hide). When I order a motor on my hard earned dollar I need to be sure it will be continuous duty. I’ve many 12 hours days at a machine.

                Was that the form factor (a24) you mentioned or the model?

                Cheers, Bob

                Comment

                • Evan
                  Senior Member
                  • May 2003
                  • 41977

                  #9
                  Free software for calculating bolt circles and similar: Click Here

                  Comment

                  • lazlo
                    Senior Member
                    • Jun 2006
                    • 15631

                    #10
                    That's a whole lot bigger motor (4 1/2" in diameter, compared with the 3" you quoted earlier) for a lot less power -- 1/2 HP.

                    That looks like a Chinese motor, right? General rule of thumb is the real HP is 50% of the nameplate HP.

                    What's the nameplate amperage?
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                    Comment

                    • Rich Carlstedt
                      Senior Member
                      • Jul 2001
                      • 5485

                      #11
                      watts = horsepower.
                      770 watts = one horsepower.

                      Throw in inefficiences, and you wind up near 1,000 (KW) watts to get a one HP from an electric motor.
                      What you will find, is that to get more HP from small motors, RPM goes up, and fan cooled motors become a necessity.
                      A Router motor is a good example, or vacum cleaner motors.
                      They need high HP in a small frame.
                      Also a Die grinder fills that bill!

                      Rich
                      Green Bay, WI

                      Comment

                      • Quetico Bob
                        Senior Member
                        • Apr 2008
                        • 350

                        #12
                        Boy’s Boy’s Boy’s, I’m not going to tell you again what do you think is going to happen when Mom gets home from work?

                        Embarrassing, but guess most of know who wears the pants.

                        Cheers, Bob

                        Comment

                        • Quetico Bob
                          Senior Member
                          • Apr 2008
                          • 350

                          #13
                          And before someone says…but.. I don’t care who started it.

                          What I’m after is a motor I can utilize, after that the sky’s the limit.

                          Evan, is that type of motor available in AC but maybe a little smaller?

                          Cheers, Bob

                          Comment

                          • lazlo
                            Senior Member
                            • Jun 2006
                            • 15631

                            #14
                            Originally posted by lazlo
                            Your calculation is correct: a 60 Watt motor is 60/746 = .080 ~= 1/12 HP.
                            Originally posted by Rich Carlstedt
                            watts = horsepower.
                            770 watts = one horsepower.
                            746 Watts per horsepower, but what's 24 watts between friends?

                            Bob: you're missing the point: that's a Chinese motor Evan linked, and Chinese motors have wildly inflated horsepower ratings. If you're looking for a specfic load at 60W with a Western motor, you need to at least double that for a Chinese motor.

                            From your description, you want something like this 1/8 HP Magnetek (from Mendelson's):




                            ...or this 1/12 HP Magnetek:

                            Last edited by lazlo; 06-11-2009, 04:19 PM.
                            "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                            Comment

                            • Quetico Bob
                              Senior Member
                              • Apr 2008
                              • 350

                              #15
                              Lazlo,
                              Little larger in the diameter than I was hoping for based on the US dollar beside it. Do you think if I waited a little longer before ordering it would get proportionally smaller?

                              Absolutely, this is along the lines of what I am seeking now if it only came with those cool racing fins.

                              Cheer, Bob

                              Comment

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