HD Hex Motor (REV-41-1291)
A Small Phillips Head Screwdriver
Press Fit Pinion
Arbor Press
1) Using a small Philips head screwdriver, remove the two small screws holding on the HD Hex Motor's Encoder Cover.
2) Remove the cover. Set it and the two screws aside for reassembly after pressing on the pinion.
3) Using a flat arbor press plate, balance the motor with the end of the shaft supported by the plate. Keep the motor shaft perpendicular to the plate and the press.
Make sure the JST VH 2-pin connector is not load-bearing in your setup, sometimes it may sit further out than the motor's shaft.
4) Press on the pinion using the arbor press. After pinion is pressed on reattach the HD Hex Motor's Encoder Cover.
5) Take care to not over-press, there should be a gap between the pinion and motor. The pinion should not be touching the body of the motor.
Brushed DC motors without a gear box can be estimated to be ~80% efficient, meaning if a motor is drawing 60 watts of power ~48 watts will be turned into mechanical energy and ~12 watts will become heat. Once a gear box is added the overall efficiency of the system goes down.
DC brushed motors can be described by some key metrics:
Stall Torque is measured when the motors RPM is zero and the motor is drawing its full Stall Current. This value is the maximum torque the motor is ever capable of outputting. Keep in mind the motor is not capable of outputting this torque for an indefinite period of time. Waste energy will be released into the motor as heat. When the motor is producing more waste heat than the motor body is capable of dissipating the motor will eventually overheat and fail.
Stall Current is the maximum amount of current the motor will draw. The stall current is measured at the point when the motor has torque that the RPM goes down to zero. This is also the point at which the most waste heat will be dissipated into the motor body.
Free Speed is the angular velocity that a motor will spin at when powered at the Operating Voltage with zero load on the motor’s output shaft. This RPM is the fastest angular velocity the motor will ever spin at. Once the motor is under load its angular velocity will decrease.
Operating Voltage is the expected voltage that the motor will experience during operation. If a robot is built using a 12 volt battery the Operating Voltage of the motor will be 12 volts. When controlling the RPM of the motor the DC speed controller will modulate the effective voltage seen by the motor. The lower the voltage seen by the motor the slower it will spin. DC motors have a maximum rated voltage if this voltage is exceeded the motor will fail prematurely.
The key metrics defined above are interrelated. Take some time to familiarize yourself with the definitions and how they connect together.
In order to ensure that an electric motor lasts as long as possible a few rules of thumb should be kept in mind:
Smooth loading - large torque spikes or sudden changes in direction can cause the wear and premature failure of gear box components. This is only an issue when the torque spike exceeds the rated stall torque of the motor. When shock loading is necessary, it is best to utilize mechanical braking or a hard stop that absorbs the impact instead of the motor.
Overheating - when a motor is loaded at near its maximum operating torque it will produce more waste heat than when operating at a lower operating torque. If this heat this allowed to build up the motor can wear out prematurely or fail spontaneously.
The Core Hex motor can run for approximately 4 hours continuously before overheating at near maximum torque loading.
Poorly supported output shaft, most motor output shafts are not designed to take large thrust forces or forces normal to the shaft. Bearings need to be used to support the axle when loads in these directions are expected.
For more information on the encoder see the Control System Guide
Electric motors are the core power plant of most robots. There are two types of motors in the REV DUO Build System: the Core Hex Motor () and the HD Hex Motor (). Both motors are brushed DC motors. The image below showcases the common elements of a bushed DC motor.
Learn more about angular velocity in the section
The prototypical performance graph of a Brushed DC motor can be used to estimate the performance of a motor. In most cases amperage, the unit of measurement for current, is the easiest value to find as it can be reported by the REV Control Hub () and Expansion Hub ().
To learn more about how to properly support motion visit the page
REV DUO Robotics motors come in two types, and . All REV DUO Motors have a Hex Shaft or female hex coupler as the output from its gearbox. The Hex Shaft is extremely reliable at transmitting torque without being reliant on set screws that can come loose or not be tightened sufficiently. REV DUO motors also include keyed locking connectors for both the motor power and the built-in encoder.
The Core Hex Motor (REV-41-1300) is a motor that features a 90 degree orientation and a female output shaft for maximum flexibility and ease of use. Insert any of the REV standard 5mm Hex Shafts into or through the Core Hex Motor to create custom length motor output shafts. The Core Hex Motor has a built in magnetic quadrature encoder which is compatible with 5V or 3.3V logic level devices including the Control Hub (REV-31-1595) and Expansion Hub (REV-31-1153).
The Core Hex Motor uses a 2-pin JST-VH Connector for motor power and a 4-pin JST-PH for sensor feedback from the built-in encoder. For more information on using the cables and connectors included with the Core Hex Motor, see the REV Control System - Cable and Connectors documentation. The image below has the pinout for the motor power and the encoder.
Output Shaft: 5mm Female Hex
Weight: 7 oz
Voltage: 12V DC
Free Speed: 125 RPM
Stall Torque: 3.2 N-m
Stall Current: 4.4 A
Gear Ratio: 72:1
Encoder Counts per Revolution
At the motor - 4 counts/revolution
At the output - 288 counts/revolution
The general recommendation is to use the Core Hex motor for lighter duty arms and intakes.
Visit the Choosing and Actuator page to learn more about how the determine what type of actuator is correct for your mechanism.
To learn more about the built in encoders and wiring for the core hex motor visit the Control System Guide.
The Core Hex Motor has two faces for mounting on two sides of the motor. The combination of the Motion Pattern is clocked to different angles on each face giving twelve different motor angles. The images below exhibit a basic mounting structure for two of the twelve positions that are available.
The images show a very basic mounting system. It is always advised to properly support elements of your robot with more 2 or more plastic brackets
HD Hex Motor (REV-41-1291) With Pinion Pressed On
A Small Flathead Screwdriver
Hex Shaft For Leverage (or similar)
1) Using a small flathead screwdriver, pry up on the base of the pinion.
2) Once the pinion has been moved enough, you may need to add a Hex Shaft or similar to give you enough leverage to completely remove the pinion.
The HD Hex Motor (REV-41-1301) features an integrated encoder and power that plug right into the REV Control Hub (REV-31-1595) and Expansion Hub (REV-31-1153). The gearbox options feature 5mm Hex output or coupler making it easy to connect gears, sprockets, wheels, etc. Encoder and power cables are always included with motor. The HD Hex Motor is similar in size and power to other brushed 550 class motors with more convenient output options and connectors.
The HD Hex Motor matches the design flexibility of other REV products with a series of compatible gearboxes to choose from. Gearbox options include the UltraPlanetary Gearbox (REV-41-1600), Spur Gearboxes, Planetary Gearbox, and no gearbox.
This section will focus on general HD Hex Motor information such as motor specifications and mounting techniques.
To learn more about gears and how they work with the HD Hex Motor visit the gears page.
The HD Hex Motor uses a 2-pin JST-VH Connector for motor power and a 4-pin JST-PH for sensor feedback from the built-in encoder. For more information on using the cables and connectors included with the HD Hex Motor, see the REV Control System - Cable and Connectors documentation. The image below has the pinout for the motor power and the encoder.
Why would you get a motor without a gearbox? Lets consider a few scenarios:
Motors Can Fail - If you have a motor that has failed but the gearbox is still in good condition, it is typically cheaper to buy the bare motor and attach the gearbox you already have.
Customization - If you want to make your own gearbox, having the No Gearbox version of the motor will make that easier.
If you are planning to make a custom gearbox keep in mind that the bare HD Hex motor comes pre-pressed with a pinion for the spur gearboxes.
Weight: 234g
Body Diameter: 37mm
Voltage: 12V DC
No-Load Current: 400mA
Stall Current: 8.5A
Free Speed: 6000 rpm
Stall Torque: .105 Nm
Max Output Power: 15W
Encoder Counts per Revolution
At the motor - 28 counts/revolution
If you are creating a custom gearbox or using the UltraPlanetary Gearbox, the specifications for the bare motor will help you calculate key metrics for your actuator.
Planetary gearboxes are designed for increased robustness when compared to Spur gearboxes, and are generally less susceptible to damaging shock loads due to more gear teeth being engaged to carry the load. There are a two planetary gearbox options from REV, the 20:1 Planetary gearbox (REV-41-1211) and the UltraPlanetary gearbox. The 20:1 Planetary gearbox has a set gear ratio where the UltraPlanetary allows for swapping out of cartridges to adjust the final gear ratio.
The UltraPlanetary System is a cartridge based modular gearbox designed to handle the rigors of the competition and the classroom. The UltraPlanetary System includes an input stage and pinion gear that works with the REV HD Hex Motor and other 550 class motors. Building on the ability to iterate and adjust designs easily using the REV Building System, the UltraPlanetary System consists of pre-assembled and lubricated cartridges allowing for swapping gear ratios on the fly and with ease. Users can configure a single-stage planetary using one of three different reduction cartridges, build multi-stage gearboxes through stacking individual cartridges together, and choose two different ways for transferring power: either through face mounting directly on the output stage or choosing the length of 5mm hex shaft best suited for the application.
The UltraPlanetary system has a variety of options for mounting with four different brackets available for mounting to REV 15mm Extrusion, REV C Channel, or REV U Channel.
For more information, including assembly tips, mounting options, and more in the UltraPlanetary Gearbox System User's Manual!
A wide range of gear ratios are possible with the three included cartridges. When combining up to three cartridges, just multiply each cartridge gear ratio to find the overall gear ratio. For example, a combination of the 4:1 and 5:1 cartridges would make a 20:1 overall gear ratio. The table below shows the common use cases for all possible ratios that can be created with the included UltraPlanetary kit.
Below are the specifications for a small sample of the options available with the UltraPlanetary Gearbox Kit.
Nominal Gear Ratio
Actual Gear Ratio
Free Speed
Stall Torque
Weight
5:1
5.23:1
1147 RPM
0.55 Nm
371 g (0.818 lbs)
20:1
18.9:1
317 RPM
1.98 Nm
405 g (0.893 lbs)
60:1
54.8:1
109.5 RPM
5.75 Nm
441.5 g (0.973 lbs)
The 20:1 Planetary gearbox features mounting holes on a 14mm bolt circle. The gearbox is compatible with the Planetary Gearbox Flat and Bent motor mounting brackets. To mount the 20:1 Planetary directly to the Extended Motion Pattern on REV Channel use a HD Hex Planetary Facemount Spacer.
Weight: 436g (including motor)
Output Shaft: 5mm hex
Output Shaft Length: 40mm
Free Speed: 300 rpm (31.4 rad/s)
Stall Torque: 297.4 oz-in (2.1 Nm)
The Spur gearboxes feature the REV Motion Pattern that is compatible with REV Motion Brackets and the Extended Motion Pattern on REV Channel. There is a second mounting pattern that is standard for most spur gearboxes. This pattern is featured on the flat and bent motor mounting brackets for Spur Gearboxes.
Product SKUs
Gearbox (REV-41-1064)
Motor with gearbox (REV-41-1298)
Weight: 350g (including motor)
Output Shaft: 5mm hex
Output Shaft Length: 40mm
Mounting Holes: 10 - M3 tapped - use a 5mm length or shorter bolt
Free Speed: 300 rpm (31.4 rad/s)
Stall Torque: 297.4 oz-in (2.1 Nm)
Product SKUs
Gearbox (REV-41-1065)
Motor with gearbox (REV-41-1301)
Weight: 350g (including motor)
Output Shaft: 5mm hex
Output Shaft Length: 40mm
Mounting Holes: 10 - M3 tapped - use a 5mm length or shorter bolt
Free Speed: 150 rpm (15.7 rad/s)
Stall Torque: 594.7 oz-in (4.2 Nm)
