Ultimate Beginners Guide to Using Electric Motors for Makers and DIY Projects; #068

here I have two DC motors this first one here the larger one is three horsepower or about 2200 watts and this little guy right next to it is 3.8 horsepower or about 2800 watts similarly I've got two induction motors this one being one horsepower and this one is 1/3 horsepower so clearly the size of the motor doesn't tell you that much about the power rating and that's one of the questions that I want to answer in this video amongst things like how to control the speed what the applications are for various motors you might Salvage and also if you hang around to the end I'll show you how I get so many different electric motors for free or very cheap alright so quick side note before we get all the way into this tackling this subject is super ambitious there are lots of different types of motors lots of ways they can be configured and controlled and so there's a high probability I'm gonna make at least one mistake in this video so be sure to check the description because I will had all types of notes there for any mistakes I may have made or things I might have missed anyway let's start with horsepower ratings now horsepower and watts are exactly the same thing sometimes people are a little bit confused by that but they're both measures of power and a horsepower rating or our power ratings are composed of two things in terms of electric motors and that is the speed or rpm and the torque torque is a measure of how much force is being applied to twist the shaft and how far away that force is being applied and this is why I wrenches come in different sizes so if you pushing a little six millimeter bulb you get this little tiny baby wrench but if you want to push it a 25 millimeter bolt you're gonna get a much bigger wrench this allows the same person to apply the same amount of force but get more torque because their lever arm is longer same thing on a seesaw you put a fat kid on the seesaw and a little kid the little kid can sit further away and balance out the heavier kid because the little kid has a greater distance he's applying less force but they both have the same torque hopefully that makes sense so if you take the twisting force applied to the shaft and multiply that by the speed which you move the shaft then now you have your power rating and that's what it is so why is it that this motor being so much larger than this one can actually have a lower horsepower rating well that's because this guy is rated for 2700 rpm and this one's rated at 3600 rpm this one can spend considerably faster but with much less torque and this one applies way more torque but not nearly the same amount of speed and this is why we have this is part of the reason why there's such a difference and then also efficiencies and some other things now one of the clues to how much torque a motor can apply is the size of the shaft so hopefully you can see the Mbita shaft there this is a 1 in 3/8 inch shaft and the shaft on this motor is only about 5/8 and that's because you're not gonna be able to plot nearly as much torque and therefore you don't need quite as large a shaft so that's the basic rundown on power ratings we could get more into that but then this video will be way too long one more thing to consider when salvaging a motor is how to get the speed that you want or the torque that you want now you can't change the power rating of a motor this guys maximum power rating is 3.8 horsepower but you can fiddle around with pulleys and gears to get different amounts of speed and torque but there's a trade-off if you try to increase the amount of torque you can get from this motor you're gonna have to give up some speed through the gear ratio and the same vice versa if you want to get more speed you're gonna have to give up some torque a lot of people will take very small motors like say this guy which I took out of a drill and try to get a lot of speed and torque from a very tiny motor let's say I wanted to use this to power a go-kart well I could give this down to get enough torque to actually get the car to move but it will be very slow remember we're trading to speed for the torque if you try for example to just increase the speed and expect this guy to push a cart really fast what will end up happening is you won't have enough power to move the cart at all it'll just sit still in my wine and make a lot of noise now if you lift the back tires up and let them spin they'll spin really fast but as soon as it hits the gray it's gonna stop because there's not enough torque to actually get the car moving so hopefully that makes sense you can exceed the power rating of the motor but you can manipulate the initial speed or torque ratio by using pulleys or gears now I do have several videos covering many of these topics and so I'm gonna put links in the description for example one about gear ratios and one about pulleys already exist on my channel and how to design what pulleys so I will put that stuff in the description so be sure to check that out all right let's start with the induction motors these are all induction motors and these three in particular all have capacitors to help them start or capacitor start induction motors capacitors most of the time look like this although this guy has a square capacitor right there on the front and the motor needs capacitor in order to get started that's important for single-phase motors this one is three-phase and it doesn't need capacitors but we'll come back to this in just a minute so we need to get capacitors in order to get the motor to start and depending upon the configuration these guys can have pretty decent starting torque they're also really good at maintaining their speeds so if you're making something that you want to have consistent speed even under load like my bandsaw for example I'm using an induction motor pretty much this same motor here to power my bandsaw and that allows me to have the same speed when the motor is just idling as well as when I'm cutting a very large piece of wood it's gonna actually draw more current in order to maintain that speed those are good things the downside to capacitors start induction motors as capacitors do fail occasionally and when that happens your motor will hum but it won't actually spin and that's a good indicator that you've got a problem with your capacitor the other problem with the single-phase capacitor start motors in particular is that it can be difficult to control their speed it's actually the line frequency from the wall that's controlling the speed of the motor and you can't easily manipulate that now there are these things called variable freak she drives which I'll talk about with this motor very few of those are available for single-phase motors for various reasons which I cover in another video and I'll put a link to that in the description but the short answer is these guys is very difficult to control their speed it's not impossible but not easy generally the best method is to use either gears or pulleys in order to get the speed or torque that you want now this particular one is called a shaded pole induction motor and you know it's a shaded pole motor because of these little copper bands that are down here in the corners this one doesn't need capacitors but the torque that it can supply is extremely low it's got almost no starting torque if you hold on to it when it start it's not gonna spend so these guys are super rugged and cheap as you can see this got very few moving parts but because they have so little starting torque you usually only see these in small fans now if you're making something that just needs to spend maybe it's decorative and it's nice and lightweight then this would be a good application for that but you're not gonna be able to do much else because the motor is so weak with this type of motor this guy here is a three-phase induction motor and there's lots of power lots of torque they're very efficient this is the ideal motor the downside to this guy is the fact that you got to have three-phase power in order to run it now in other countries outside the US many people have three-phase power at home but here in the u.s. we don't have such a luxury it's pretty much only available at industrial sites but you can buy speed controllers for these types of motors in fact I'll show you what so this for example is a variable frequency drive and it takes single-phase power in and converts such a three-phase powerful your motor and in between there's a dial that lets you control the speed as well and here's another one that doesn't have a digital interface but it's a variable frequency drive which takes single-phase power in and converts it to three-phase power and if you're somewhere where you have three phase and you want to control the speed they sell these as three-phase to three-phase as well so there are many options available for this but these guys would not try to use a variable frequency drive now there are lots of little caveats here like there are some induction motors where you can buy a VFD for the single-phase motor but that's a very special type of motor and it's a topic that's way outside of the scope of this video if your induction motor has capacitors I would not use the VFD although again there's some caveats like you could technically use it to speed the motor up but not slow it down but again we're getting off into tangents here I would just suggest you stay away from that and use pulleys in order to adjust the speed for these single-phase capacitor star induction motors that is a mouthful this is a motor that I took out of a blender it's a universal motor which means it can run on both AC and DC it can be wired directly to 120 volts if you're in another country depending upon what motor is it might be 240 and it can also run on DC I could hook this up directly to a battery and get it to run as well the downside is it does have these motor brushes like the permanent magnet DC motor and so that's a wear component that will eventually fail on you and need to be replaced the other thing about the universal motor is it doesn't maintain a speed under load so even though you they are speed controllers that you can use with a universal motor you can get the speed out in and let's say for example I was using this for my bandsaw I might be able to dial it in with the speed controller a DC speed controller SCR there are lots of options there but once you actually put it under load for example once I start cutting a piece of wood then this guy will begin to bog down and slow down so if you need consistent speed on the loader this is not the motor for you this is better used in applications where the final speed doesn't matter very much otherwise you get a lot of power in a very small package and it's a nice Universal Universal motor so again you find these and things like blenders and fans and vacuum cleaners things like that at least here in the US some vacuum cleaners overseas as I understand it actually use induction motors oh and that brings up another point washing machines overseas often use Universal motors for the washing machine but this motor that I showed you earlier came out of a washing machine here in the US but that's the induction motor so just in case there's any discrepancies in the description there it might be because of the country you live in all right these two are permanent magnet DC motors this one I took out of a treadmill and this one came out of a small circular saw and very similar motors also come from hand drills these two motors are super simple they can be powered by DC power so that makes them very portable for applications where you want something to move or you need it in a very small lightweight package you'd be looking for a motor something like this there's several ways that you can control the speed of a DC motor you can buy a DC motor controller which I've got one in my lathe but I also often use the speed controller that comes with the treadmill so this guy for example is a MC 2100 and in order to control this you're going to need something that can produce a PWM signal I've done this with an Arduino I can be done but I haven't made a video about that just yet so if I would make a video on that I will come back and put it in the description but I don't have a video specific to the MC 2100 which needs the PWM but I did make this guy in a previous video and this also uses a treadmill speed controller I think there's an MC 70 in here but the MC 70 the MC 60 and I even think to MC 80 can all be controlled by just plugging in a potentiometer and if you watch this video I'll show you how to wire that and then you've got a speed controller I'll use this as a benchtop power supply but all the instructions are in that video and there's a link in the description if you want to control a motor like this we've also got these two guys which are stepper motors I took these out of an industrial printer the good thing about stepper motors is they give you super precise movements man you can get this guy to move exactly 0.9 degrees of rotation or even smaller increments than that depending upon the size of the motor will obviously dictate how much power you can get from that motor and these also come in standard configurations usually they have a NEMA rating I don't think this one has one at least not on the box but typical sizes will be like NEMA 17 name a 23 and NEMA 34 those are correspond to dimensions so two NEMA 34 motors aren't necessarily the same power or even the same motor it's just a relationship between the bolt pattern and I believe also the shaft size that allows you to replace one NEMA 34 with another name 134 and even increase your power to your machine or something like that by getting a larger NEMA 34 motor but again it would have the same boat pattern on the face to allow you to use the same mounting the downside to motors like this is they need sophisticated drivers because it means very precise instructions from a computer so typically you would have something like this I haven't even opened this yet but this is a power supply which converts the AC to DC and steps to voltage down in this case it steps it down to 60 volts and that's what my stepper driver needs and this driver is what converts all the electrical signals from the computer into actual mechanical motion on the stepper related to this I don't have one here in the shop but similar to these stepper motors will be servo motors the difference is those are usually brushless DC motors or AC synchronous motors and they have a little encoder on the end of the shaft and that tells the computer exactly where the shaft is in space throughout its rotation and it can produce a lot of power and a lot of speed so you find those and really large industrial machines servo motors typically come in industrial size CNC machine like what you might see in a massive milling machine here we have a brushless DC motor BLDC which has a little gear box on the top some of the benefits of brushless DC motors is the fact that they don't have brushes so they're no wearing parts they have good power and torque similar to the three-phase AC motor in fact they're sometimes called AC motors because of some similar because of its similarities to the three-phase AC motor but that's a little bit outside of the scope of this video but you're going to absolutely need a controller you can't just worry this guy to the wall or to a battery and get it to run you have to a couple of this with a controller to get it to do anything and just to make things a little bit more complicated there are brushless DC motors with sensors and then there's a sensorless brushless DC motor I don't want to get too much into that in this video but I do want to point out that you need to be sure which one you have whether it's the censored or the cents or less because that's going to determine what kind of controller you use in order to run the motor ok let's talk real quick about how to get these motors for free so everything you see on this bench from here over what's free and on this side was like dirt cheap this motor here on the end this massive three horsepower DC motor I bought at an auction in industrial auction I think I did like 20 bucks on it nobody else bid on it if that number is wrong I'll put it on the screen I don't remember exactly how much I paid for it next I want to tell you about these guys so this is just two of a group of six I bought six one horsepower three-phase motors three of them had the gearbox on the end like this and three of them were like this just a bear chef and I paid $300 for the whole group I've already described this guy to you but I got this out of a treadmill and in fact treadmills are by far the easiest to find I mean I just picked up to within a couple days of each other the other day and treadmill motors typically have two to three horsepower motors typically I will find these guys on Craigslist or Facebook marketplace and it only takes maybe about a week of watching regularly before you can final at least my area locally depending upon what you live it might take longer searching online makes it really easy and sometimes you just drop by and see them sitting on the side of the road if you leave for work a little early give yourself some time you can stop and load it up this universal motor you will often find in small household appliances because I got this out of a blender same thing sometimes people are just giving that stuff away on Craigslist or Facebook marketplace in this case my blender broke and the little blade broke off you can't buy a replacement blade I took the motor out of it and there you go this one I think I mentioned earlier came out of a wood chipper and I found that just walking through my neighborhood one of my neighbors was throwing away their wood chipper and I dragged it home and took the motor out of it these two came out of washing machines found the same way for these DC motors again these are induction motors if you live in another country outside the US they may be universal motors and the wiring is different but the same premise applies these guys are free and people are often just getting rid of them and in fact in some cases people will actually pay you to come get it just to get it off of their property because they don't have a way of loading it up or getting rid of it this guy here is a linear actuator with a small induction motor here that is geared down and this is the lift motor from a treadmill so I've got a bunch of these generally when you get this you will also get this if you have any questions about the things that I mentioned here put them in the comments below lots of comments come in when I post these videos and I do read them all but I can't reply to all of them so my plan is to take the most common questions that come up and add notes to the description for the common questions and I'll try to answer them there so again I'm sending you to the description please be sure to check that before you comment because I may have already answered your question I gotta tell you this has been a lot of fun this is like one of my favorite topics so I hope you found this useful thanks for watching

Channel: Jeremy Fielding

Views: 1,582,259

Rating: 4.9572673 out of 5

Keywords:

Id: SrPHQh-M3pM

Length: 19min 46sec (1186 seconds)

Published: Wed Feb 20 2019