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I need an electric motor:120v. 1/8hp.variable rpm from 0 to 200rpm. rpm control via some type of knob. can't be multiple fixed speed.20 inch/lb torque.cheap. used is fine provide that its in good condition. & under $120can anyone point me in th right direction?I was thinking celing fans with variable speed... all I know about electric motor is how to turn it on/off & that they need to ne plugged in.
Reply:for some pretty good torque you could look for a used treadmill motor.ErnieThis cat does it doggie styleMiller Bobcat 225Miller Matic S52ACT520D TIG/Arc/Plasma
Reply:i have a treadmill I wouldn't mind donating for this project. however, it might be too bulky and too much torque (uh, did I just say "too much torque"? I'm getting old)
Reply:Too much torque?!! Anyway you can use a good "ol' fashion" dimmer switch to control the speed of any 120v. A/C motor indefinitely. Problem being, some motors can't handle speeds they are not specifically built for. Too slow or too fast can create too much heat causing them to burn out.Last edited by papabear; 12-24-2009 at 11:54 PM."SOUTHPAW" A wise person learns from another persons mistakes;A smart person learns from their own mistakes;But, a stupid person.............never learns.
Reply:old sewing machine motors work great for this.
Reply:go to your local radio shack and you should be able to pick up a ria-stat for the variable control.I break things for a living...
Reply:Papabear, I thought using the dimmer. my assumption was that, if i were to pair a dimmer with a 300 rpm motor, then with the dimmer set at 50%, the motor would spin at roughly 150rpm? Good thing you mentioned the burning out issue, i'll make sure i'll test this out with a motor i can afford to burn up.kneedeep, funny you mentioned sewing machine, i have two! one works perfectly, and one doesn't work too well (wont reverse) I thought about using old fashion electric mixers as well, but i dont have a mixer, I guess i will try using the sewing machine motor.smokin-dodge, thanks for the heads up on radio-shack. i have completely overlooked the obvious.
Reply:Unfortunately most Radioshacks don't carry all that much in parts any more. I sometimes help out a buddy that does electronic repairs and frequently if we run out to RS they dont have even the basic parts. Guess I can't really blame them. Almost no one repairs electronics anymore. It's all plug and play. If a board has a problem, you pull the whole board and stick in a new one. Very few try to figure out what parts wrong and fix it.Oh and don't expect the counter guys to have any clue about their parts stock. Usually they don't even know that they have the parts let alone know what in the world they are used for..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Find a motor that has "brushes" in it, then go to horrible freight and get thier router speed controller for $20. Sorry for not seeing this thread earlier.
Reply:How about a cheap vs drill motor, HF should have one.
Reply:Originally Posted by DSWUnfortunately most Radioshacks don't carry all that much in parts any more. I sometimes help out a buddy that does electronic repairs and frequently if we run out to RS they dont have even the basic parts. It's all plug and play. If a board has a problem, you pull the whole board and stick in a new one. Very few try to figure out what parts wrong and fix it.Oh and don't expect the counter guys to have any clue about their parts stock. Usually they don't even know that they have the parts let alone know what in the world they are used for.
Reply:Wow - finally something I can talk about!Could you please describe your application? It sound like you want good control over speed along with good torque and that will not work so well with small AC motors. AC motors do not lend themselves well to speed control if you want a cheap solution and variable speed, particularly over the entire range of speeds you quoted. A router speed controller will not work well in such an application - slow speeds will result in low torque.Most of the people who want good control over a range of speed go with DC motors. There are a bunch of folks who have converted their small metal lathes to DC motors. Look on google under "DC motor lathe". Three options exist if you want good control over speed and they are all DC motors. Your price target may be hard to achieve, even with used stuff. Who knows, you may get lucky. Anyway, here goes: Treadmill Motor Pros: Cheap, Motor Controller has built in conversion to DC, high torque Cons: Big (not less than 3/4 hp), Fast (2000+ rpm)DC Gear Motor Pros: Cheap, Small, Easy control with a potentiometer, Good medium and fast speed control - not so good on the low end Cons: Generally Low Torque (there are exceptions), Requires External DC power supply and controller.Stepper Motor Pros: Cheap, Controller and Motor Readily Available, Great speed control over entire range. Cons: Requires external DC power supply, high torque steppers = big money.Note that none of these motor types and their controllers are sealed from the elements.You'll have to figure out a way to seal the motor, controller and power supply. My vote is for a DC gear motor if you don't need super low speed control. Here is an example of a DC gear motor setup:Gear Motor: surpluscenter.com. They have the following item that mightfit your application - 280 RPM 12 VDC GEARMOTOR, Item number: 5-1623. DC power supply: Capable of at least 20 amps to power this beast. See ebay, item number 280334884766.Motor Controller: Look under "pwm controller" on ebay. One example controller is item number 140319836552 on ebay.Sorry for being so long winded. Good luck!Last edited by karlgabel; 12-30-2009 at 12:23 AM.
Reply:I can also put together an example of a stepper motor solution if you are interested. Let me know!Last edited by karlgabel; 12-30-2009 at 12:26 AM.Reason: More information
Reply:motor will only be used indoors, no need to weather proof it. I dont know what gear motor nor stepper motor are, so i'll google them as soon as i finish the reply here.I do have a treadmill that i'm willing to donate for this project. are ALL treadmill's DC? the said treadmill has a electric panel with pre-programmed speed AND speed adustment (up and down) via push button. I'm assuming i can use this motor with some sort of potentiometer (sorry, i dont kwow what i'm talking about) knob?so am i correct if i hook it up like this:wall outlettopower supplytocontroller and DC treadmill motorby the way, i'm using a sewing machine motor as a temporary substitute for now.Last edited by oxy moron; 12-30-2009 at 02:37 PM.
Reply:I built a positioner a while back and used a Bodine DC motor and controller.In the pic below, the 90 VDC motor and controller are towards the bottom.The controller plugs into a 110v wall outlet and connects to the motor.Ebay is a good source for Bodine equipment. Both the motor and controller listed for over $500.00.....Ebay....under $50.00 each.Also, check out the Bodine website. A lot of good info to be had!Rex
Reply:A rheostat will work for a brushed motor. Not for an induction repulsion motor. Single phase repulsion induction motors have a start winding, that would not disengage until the proper rpm's are reached. Even some brushed motors will overheat because their cooling fans are not designed for cooling the motor at reduced rpm's for any length of time.Even a fan motor that has no start winding, will over heat, because it will, what they technically call "slip". The hertz of your household current control the speed of motors, like clock motors especially, with great accuracy. And they also set the rpm's of repulsion induction motors. Regardless of how much voltage you feed them. The hertz are trying to turn the motor, at the nameplate rpm's. When the hertz cannot sync to the motor speed. The motor draws more amps and overheats even more quickly. Because the motor is slipping so much. So you have to get a frequency generator. That maintains the proper voltage, while adjusting the number of opposing polarity AC cycles a second, sent to the motor. This way you can still get a lot of power from the motor, even at lower speeds. I do not know if all you guys know this. But if you are really pressing a drill motor or other brushed device beyond it's limits. And you smell or see smoke. Just let the motor run at full rpm's with no load, and the fan will cool it off almost immediately. It is much better to do that then to let it stew in its own heat. And if you are trying to get something done with it or have to get something done with it. It will also cool off more quickly if you just let it free wheel between over heating. Sincerely, William McCormick
Reply:I like rode2rouen's solution. Bodine makes some great products and has been in the business for years. Of course there are Baldor (pricey) and Dayton. |
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发表于 2021-8-31 23:59:54