{"id":5669,"date":"2019-03-21T13:57:05","date_gmt":"2019-03-21T17:57:05","guid":{"rendered":"https:\/\/dronebotworkshop.com\/?p=5669"},"modified":"2019-04-06T11:03:48","modified_gmt":"2019-04-06T15:03:48","slug":"real-robot-003","status":"publish","type":"post","link":"https:\/\/dronebotworkshop.com\/real-robot-003\/","title":{"rendered":"Build a Real Robot &#8211; Part 3 &#8211; Selecting Motors"},"content":{"rendered":"\n<p><span style=\"font-weight: 400;\">This is the third installment in a continuing series on building a real robot. You can also read <a href=\"https:\/\/dronebotworkshop.com\/real-robot-001\/\">Episode 1<\/a> and <a href=\"https:\/\/dronebotworkshop.com\/real-robot-002\/\">Episode 2<\/a> if you haven\u2019t already so that you can bring yourself up to speed.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Introduction<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">In this installment of the Build a REAL Robot series, I will discuss selecting DC gearmotors, a critical component for your robot design. Even if you are not building the same robot that I am creating you should find some useful information here.<\/span><\/p>\n<div class=\"youtube-player\" data-id=\"q-LSxYCuaso\"><\/div>\n<p><span style=\"font-weight: 400;\">I will also show you what motors I ended up using to design DB1, and how I mounted them onto the chassis.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">DC Gearmotors<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">There are a wide variety of motors that are available for the hobbyist, but not all of them would be suitable for moving a robot around. \u00a0A few possible selections would be:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><b>Brushed DC Motors<\/b><span style=\"font-weight: 400;\"> &#8211; These are inexpensive and easy to power and control, however, they spin much too fast. You could use gears to reduce the torque and increase the RPM, essentially building your own DC gearmotor.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Brushless Motors &#8211; These are pretty expensive but they do perform well. Like the Brushed DC motor you would need to gear them down to reduce RPM and increase torque. They also require special circuitry to drive them. One advantage of these motors is their long life, they are also very quiet.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>Stepper Motors<\/b><span style=\"font-weight: 400;\"> &#8211; You can get very powerful steppers that would certainly be able to drive a robot, and since you can control the shaft rotation is small increments they would be great for positioning the robot exactly where you want it to be. \u00a0The ride might be a bit rough as they don\u2019t spin in a linear fashion, but using microsteps or gearing them down would resolve that. The main drawback would be the cost of these motors.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>Continuous Rotation Servo Motors<\/b><span style=\"font-weight: 400;\"> &#8211; You could build a small robot with these but they would not be very good for a large one. Essentially these are geared DC motors with a built-in servomechanism. The servomechanism would make it easy to position the robot.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>DC Gearmotors<\/b><span style=\"font-weight: 400;\"> &#8211; DC motors with internal gearing. Some of them have Rotary Encoders to measure the position of the motor shaft. These are the types of motors I have chosen.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Another reason to choose a DC gear motor is their relatively low cost, giving them a good cost-to-performance ratio. \u00a0They are widely available from many distributors.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5678\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Selecting-Robot-Motors.jpeg?resize=750%2C422&#038;ssl=1\" alt=\"Selecting Robot Motors\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Selecting-Robot-Motors.jpeg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Selecting-Robot-Motors.jpeg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">When you are searching for DC Gearmotors you will probably run across different gearing arrangements. The most common ones are Planetary Gears and Spur Gears.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Planetary gears offer better performance and reduced noise, this extra performance comes at a higher price however.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">I chose to use Spur gearmotors. They are still very efficient and powerful and their lower cost appealed to me. I do admit they are a bit noisy but I wasn\u2019t designing DB1 to sneak up on anyone so I\u2019ll accept that!<\/span><\/p>\n<p><span style=\"font-weight: 400;\">You could substitute Planetary gearmotors in this design if you wish.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Key Motor Specifications<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">When you go to select a DC gearmotor you may find yourself overwhelmed by the number of specifications you need to wade through. \u00a0Comparing motors is often made more difficult as not every manufacturer uses the same units for each parameter.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">You can\u2019t just grab any motor, choosing the wrong one can be an expensive mistake that will halt your robot project before you even get started.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Here are a few specifications you need to take into consideration.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Nominal Voltage<\/span><\/h3>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5677\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Nominal-Voltage.jpeg?resize=750%2C422&#038;ssl=1\" alt=\"Nominal Voltage\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Nominal-Voltage.jpeg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Nominal-Voltage.jpeg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">The <\/span><i><span style=\"font-weight: 400;\">Nominal Voltage<\/span><\/i><span style=\"font-weight: 400;\"> is the voltage at which the motor is operating at peak efficiency.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">This should not be confused with <\/span><i><span style=\"font-weight: 400;\">Operating Voltage<\/span><\/i><span style=\"font-weight: 400;\">, which is generally specified as a range from the minimum voltage required to turn the motor shaft to the maximum voltage that the motor can handle safely.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The ideal Nominal Voltage is basically determined by the power supply (or battery) that you plan on using to power the motors. Common values are 6, 12 and 24 volts.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">All of the specifications for the DC gearmotor will be measured when it is driven by the nominal voltage<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">No Load RPM<\/span><\/h3>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5676\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/No-Load-RPM.jpeg?resize=750%2C422&#038;ssl=1\" alt=\"No-Load RPM\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/No-Load-RPM.jpeg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/No-Load-RPM.jpeg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">The <\/span><i><span style=\"font-weight: 400;\">No Load RPM<\/span><\/i><span style=\"font-weight: 400;\"> is the revolutions per second of the motor shaft when there is nothing attached to it. \u00a0This is sometimes referred to as the motors \u201cangular velocity\u201d.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">With a gearmotor this is the RPM of the output shaft, not the RPM of the DC motor powering the gears.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Note the term \u201cNo load\u201d, when you connect a gear, a wheel or other devices to the shaft the RPM will decrease.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">This is an important specification as it determines the maximum speed that your robot can travel. \u00a0If you are using gears or pulleys in your design you will have to factor these into the equation for determining the No Load RPM.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Stall Torque &amp; Stall Current<\/span><\/h3>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5679\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Stall-Torque-Stall-Current.jpeg?resize=750%2C422&#038;ssl=1\" alt=\"Stall Torque &amp; Stall Current\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Stall-Torque-Stall-Current.jpeg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Stall-Torque-Stall-Current.jpeg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Before you can understand Stall Torque you need to understand what torque is. \u00a0This is an extremely important specification as it essentially determines how powerful the motor is.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Essentially torque is a measurement of force on an object that causes it to rotate. \u00a0Think of when you go to open a door, you need to apply force to the door to open it, or in other words, rotate it on its hinges.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Torque can also be described as a weight attached to the end of a lever, which has the other end attached to a (motor) shaft. The further away from the motor shaft you place the weight, the more torque is required to hold it there. Similarly, when you increase the weight you require more torque to hold it. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">The official <\/span><a href=\"https:\/\/en.wikipedia.org\/wiki\/International_System_of_Units\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">SI unit<\/span><\/a><span style=\"font-weight: 400;\"> for measuring torque is the Newton Metre, or NM. \u00a0However, when you go to choose a motor you are more likely to see it measured in one of the two following units:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><b>kgf-cm<\/b><span style=\"font-weight: 400;\"> \u00a0&#8211; Kilogram Force-Centimetres<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>ozf-in<\/b><span style=\"font-weight: 400;\"> \u00a0&#8211; Ounce Force-Inches<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Often when you see the specifications they are written (incorrectly) as \u201ckg-cm\u201d or \u201coz-in\u201d, their meanings are identical.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The <\/span><i><span style=\"font-weight: 400;\">Stall Torque<\/span><\/i><span style=\"font-weight: 400;\"> is the torque at which the motor shaft can no longer turn. \u00a0You should never actually allow your motor to come anywhere near this point, in fact you should design your robot to never require more than 30% of the Stall Torque.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The <\/span><i><span style=\"font-weight: 400;\">Stall Current<\/span><\/i><span style=\"font-weight: 400;\"> is the amount of current that the motor will require at the Stall Torque point.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">You don\u2019t need to design a motor driver that can handle the Stall Current, in fact there are very good reasons not to do this. If the driver is capable of supplying enough current to power the motor at the Stall Current point you run the risk of damaging the motor if the shaft is accidentally held in place. \u00a0If it can\u2019t supply enough current then you will never achieve the stall torque or current.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Of course a fuse is another way of ensuring that you never achieve the stall current. \u00a0We will discuss this in more detail when it&#8217;s time to hook up our motors.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Motor Size and Motor Shaft Specifications<\/span><\/h3>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5674\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Size-Specifications.jpeg?resize=750%2C422&#038;ssl=1\" alt=\"Motor Sizing Tool\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Size-Specifications.jpeg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Size-Specifications.jpeg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">The physical size of the motor is naturally a specification you\u2019ll need to consider. After all, if it\u2019s too big you won\u2019t be able to use it!<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Another very important specification is the location of the mounting holes, their spacing and the thread size they use. You\u2019ll find a variety of SAE and Metric measurements used here.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The diameter and length of the motor shaft are important parameters as well. When you are coupling your motor to wheels, hubs or gears you\u2019ll need to take the shaft diameter in mind. Once again these specifications can be listed in either metric or SAE measurements.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Finally, you should note that spur gearmotors, like the ones I\u2019m using in DB1, have an offset shaft. You\u2019ll need to take that into consideration when mounting your motors.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Gear Down<\/span><\/h3>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5671\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Gear-Down.jpeg?resize=750%2C422&#038;ssl=1\" alt=\"Gear Down\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Gear-Down.jpeg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Gear-Down.jpeg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Gearmotors (obviously) use gears to reduce the motor speed. Doing this accomplishes two things.<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">The output RPM is reduced to a manageable level.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">The torque is increased.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">The relationship between the speed reduction and torque is inverse, so gearing the motor to half of its speed will double the torque. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">A good example of this effect is to look at those tiny yellow motors used in \u201crobot car bases\u201d, the type I\u2019ve used in many project before. Despite their size they produce an impressive amount of torque. This is because they are geared down.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The <\/span><i><span style=\"font-weight: 400;\">Gear Down<\/span><\/i><span style=\"font-weight: 400;\"> is the ratio of the gearing. The motors I\u2019m using are geared down to 53, so the output shaft will spin at 1\/53 of the actual motor speed.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">One reason you might need to know the Gear Down is when you are using a rotary encoder to measure motor revolutions, as in many designs these encoders are coupled to the internal motor and not the output shaft. This is not universally true however.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Rotary Encoders<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">I just mentioned Rotary Encoders, these are devices that can measure the angular position of the motor.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">A Rotary Encoder is essential to the design of DB1, as it will allow us to determine how fast the robot is travelling and how much distance it has moved. We can use this as part of a feedback loop to position our robot precisely.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">You can buy motors with rotary encoders already built-in, this is what I did. You can also purchase these devices separately, if you sdo you should make sure to buy ones that are compatible with your motor.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Motor Selection Tool<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">All of the above may seem like a lot to consider when choosing a motor, and it is. It also doesn\u2019t help if you don\u2019t know the answer to some of the basic questions, such as:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">How much torque will I need for my motors?<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">What RPM do I need?<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Answering these questions can require some pretty complex calculations. And, once you find the answer, you may need to convert the units to compare different motors.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Fortunately,\u00a0there is an easier way.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The RobotShop Community Blog has an excellent tool specifically made for selecting robot motors. \u00a0You will find their <\/span><a href=\"https:\/\/www.robotshop.com\/community\/blog\/show\/drive-motor-sizing-tool\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">Drive Motor Sizing Tool<\/span><\/a><span style=\"font-weight: 400;\"> to be incredibly useful.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5675\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Sizing-Tool.jpg?resize=750%2C422&#038;ssl=1\" alt=\"Motor Sizing Tool\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Sizing-Tool.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Sizing-Tool.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">One of the great things about this tool is that you don\u2019t need to know much more than the weight you want your motors to carry (the robot itself and any payload), the number of powered wheels and the size of those wheels.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The tool will also allow you to input and display parameters in several different units, so you can compare results for motors that use different units for their specifications.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Motors for DB1<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Now that we have discussed motor specifications I\u2019ll show you the motors that I choose for the DB1 robot.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\">I\u2019m using two motors in my design and, with the assistance of the RobotShop <\/span><a href=\"https:\/\/www.robotshop.com\/community\/blog\/show\/drive-motor-sizing-tool\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">Drive Motor Sizing Tool<\/span><\/a><span style=\"font-weight: 400;\">, I determined the desired RPM and minimum torque. I then chose motors that came closest to the RPM &#8211; a little higher is better than a little lower. They also exceeded the torque requirements, while not consuming a huge amount of current.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Motors used in DB1<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">I used a <\/span><a href=\"https:\/\/www.servocity.com\/5201-series-53-1-ratio-105-rpm-spur-gear-motor-w-encoder\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">goBILDA 5201 Series Spur Gearmotor <\/span><\/a><span style=\"font-weight: 400;\">with a 53:1 gear down ratio. \u00a0This model has a no load RPM of 105 RPM, which is quite fast enough for my application.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5673\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Mount.jpg?resize=750%2C422&#038;ssl=1\" alt=\"Motor Mount\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Mount.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Motor-Mount.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">The Actobotics Aluminum Motor Mount E was what I used to attach the motor to the chassis.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The motor has a stall torque of 720 ozf-in and a stall current of 9.2 amperes. The no load current is 250 mA. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">The output shaft is 6mm in diameter, I used a <\/span><a href=\"https:\/\/www.servocity.com\/set-screw-shaft-couplers\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">\u00bc\u201c to 6mm shaft coupler<\/span><\/a><span style=\"font-weight: 400;\"> to attach the <\/span><a href=\"https:\/\/www.servocity.com\/0-250-1-4-stainless-steel-d-shafting\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">\u00bc\u201d D-shaft<\/span><\/a><span style=\"font-weight: 400;\"> I am using for my axel. <\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-5672\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Gearmotor-Wheel.jpg?resize=750%2C422&#038;ssl=1\" alt=\"Gearmotor with Wheel and parts\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Gearmotor-Wheel.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Gearmotor-Wheel.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">On my wheel I used a <\/span><a href=\"https:\/\/www.servocity.com\/0-770-clamping-d-hubs\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">hub with a \u00bc\u201d D-shaft bore<\/span><\/a><span style=\"font-weight: 400;\">. \u00a0I\u2019ll go into more details about mounting the wheels in the next installment of this series when I discuss wheels in depth.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Conclusion<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">This completes part three of the series on building a real robot. I hope it inspires you to build your own robot, be it an exact replica of DB1 or a completely different and unique design.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">If you haven\u2019t read part 1 or part 2 yet you can go back and catch up. Next time I&#8217;ll be discussing wheels, not exactly the most thrilling subject but an essential one for making a good reliable robot chassis. After that, we will start adding some electronics to make it all move.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Stay tuned!<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the third installment of the &#8220;Build a REAL Robot&#8221; series I will show you how to select DC gearmotors for your robot.  I&#8217;ll also show you the motors that I used in the DB1 design, and how I mounted them to the chassis.<\/p>\n<p>In addition, I&#8217;ll introduce you to a very useful online tool for selecting robot motors<\/p>\n","protected":false},"author":1,"featured_media":5678,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[88,4],"tags":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2019\/03\/Selecting-Robot-Motors.jpeg?fit=768%2C432&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p74ClK-1tr","jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts\/5669"}],"collection":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/comments?post=5669"}],"version-history":[{"count":0,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts\/5669\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/media\/5678"}],"wp:attachment":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/media?parent=5669"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/categories?post=5669"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/tags?post=5669"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}