45mm x 45mm U Channel Basics

REV 45mm U Channel has a 45mm x 45mm square profile, and is designed to work seamlessly with existing REV 15mm Extrusion. It can be used in locations where additional torsional strength is required. On the sides of the channel is the Extended Motion Pattern which uses M3 hardware for attaching brackets, extrusion, and channel together. Locations for mounting bearings, shafts, motors, and servos are available every 16mm. Slots on the top of the channel accept standard M3 hex-head bolts or nuts, rather than expensive t-nuts. The top of the channel also has the Motion Pattern with M3 holes on a 16mm diameter circle pattern repeating down the channel.

Product Specs

• Material: 6063-T6 aluminum

• Height: 45mm

• Width: 45mm

When to use?

Similar to the , the U Channel is great for applications that need additional torsional strength. The advantage of the U channel over the C Channel is that the shape, combined with the Extended Motion Pattern, allows for two points of shaft support. This reduces the need for additional support brackets in different applications, such as drivetrains and arms.

Use the U channel in places where you need a high level of torsional strength.

How to Use?

The combination of the pitch and extrusion systems featured on the U channel allows flexibility in design and iterations. The extended motion pattern featured allows for easy placement of moving parts, for additional constraint and support of motion.

The major use applications are that Core Hex Motors () and Servos () can fit completely within the U Channel and be mounted flush against the channel without the need for brackets. Simply attach build components with M3 hardware.

The REV DUO line of parts work together for a dual purpose: to create competition-grade robots geared towards participating in the FIRST Tech Challenge or to be used in the classroom for STEM Education.

REV Robotics is committed to designing high-quality products that make robotics accessible for any skill level. Since 2014, we have continued to iterate and adapt to the educational robotics community's needs by developing new products and refining our current product selection.

What is REV DUO?

REV DUO is a new brand that now includes all of our existing products and is the new home for many new products coming soon. Look for the REV DUO flag and logo on our website, and shop with confidence knowing all products are compatible and designed to work together seamlessly.

If there is a question that is not answered by this documentation, send our support team an email; [email protected]. We are happy to help point you in the right direction.

15mm x 30mm Extrusion Basics

The 15mm x 30mm profile of the has slots on on all four sides that accept standard. Rather than using a T-nut, which is more expensive, slide a M3 hex head screw along the slot and adjust brackets and other build materials as needed. As illustrated in the image above, the ends of the Extrusion also have a 5mm hole pitch that can be M3 tappped. The 15mm x 30mm Extrusion has one slot on each 15mm face and 3 slots on each 30mm face, allowing for some additional design flexibility when compared to the standard 15mm extrusion.

15mm Extrusion Basics

The 15mm profile of the has slots on on all four sides that accept standard . Rather than using a T-nut, which is more expensive, slide a M3 hex head screw along the slot and adjust brackets and other build materials as needed. As illustrated in the image above, the ends of the Extrusion also have a 5mm hole pitch that can be M3 tappped.

HD Hex Pinion Pressing Guide

Needed Materials:

• HD Hex Motor (REV-41-1291)

• A Small Phillips Head Screwdriver

• Press Fit Pinion

• Arbor Press

SRS Basics

The REV Robotics Smart Robot Servo (SRS) () is a configurable metal-geared servo that takes the guesswork out of aligning and adjusting servo based mechanisms. One SRS can be used as a standard angular servo, a custom angular servo, and a continuous rotation servo by simply changing its settings.

Flat Plate Basics

is a 45mm wide, bendable metal featuring the Extended Motion Pattern. This product comes in various lengths. The Extended Motion Pattern supports for attaching brackets, extrusion, and channel.

Structure Basics

The REV DUO Build System has two major structural components, Extrusion and Channel. REV Extrusion is a rectangular structure rail with slots for M3 hardware on all four sides. The slots in the Extrusion allow for brackets and other items to be adjusted to any position along the rail. REV Channel is a larger structural member featuring a pattern for actuators, brackets, and other elements to be placed at set intervals. Channels have a combination of a fixed pitch based system (known as the Extended Motion Pattern) and an extrusion system for design flexibility.

All REV DUO structural components are M3 hardware compatible.

Extrusion System Versus Pitch System

The 15mm extrusion system allows for a more flexible, iterative process than fixed pitch systems. Fixed pitch based systems have a set pattern of holes to use for mounting; everything that is mounted is spaced on a multiple or a set fraction of the standard pitch. In contrast, the 15mm extrusion system allows for flexible mounting positions along the slots. Simply slide any brackets that need to be mounted into the appropriate slot and adjust to the desired position.

We believe that the easier it is to adjust your design, the easier it is to iterate and improve that design.

See any of the pages linked below to learn more about how to use the extrusion system.

Extended Motion Pattern

While the 15mm Extrusion does not have a fixed pitch other components in the REV DUO Build System do. have M3 holes on an 8mm pitch. While have the Motion Pattern, a circular M3 hole pattern on a 16mm diameter is used to mount to REV Robotics shaft accessories.

, , and feature the Extended Motion Pattern, a modified circular M3 hole Motion Pattern on a 32mm diameter. This repeats down the length of channel to mount bearings, shafts, brackets, and more.

The Extended Motion Pattern starts with M3 holes on an 8mm pitch down the center of the Channel. Each of the holes on the center line pitch forms the "base" for an equilateral triangle with 8mm sides that extends outward towards the edges of the Channel. Every 16mm a center hole is opened up to become a 9mm bearing seat to attach shafts and bearings.

Flat Beam Basics

These aluminum beams are simple and versatile. Having an 8mm width, 3mm height, and 8mm hole pattern makes them perfect as a support for an upright, or for use as a linkage.

Product Specs

• Material: 6063 Aluminum

• Length:

• Width: 45mm

Mecanum wheels, when properly set up on a drivetrain, allow for omni-directional movement. Each Mecanum Wheel Set (REV-45-1655) comes with a two right (REV-41-1656) and two left (REV-41-1657) mecanum wheels. This is determined by the direction of the leading edge of the rollers. If the rollers point left it is a left wheel and if they point right it is a right wheel.

Each side of the chassis needs one left and one right wheel. Mecanum Chassis also require four motors for operation.‌

To know if your Mecanum Wheels are properly configured look from the top down on the drivetrain. Following diagonal lines created from the angle of the rollers should form an "X" as shown above.‌

Mecanum Wheel Drivetrain Behavior

Running all four wheels in the same direction at the same speed will result in a forward/backward movement, as the longitudinal force vectors add up but the transverse vectors cancel each other out, as shown below.‌

When both wheels on one side of the drivetrain are moving in one direction while the other side is moving in the opposite direction results in stationary rotation of the drivetrain. The transverse vectors cancel out but the longitudinal vectors combine to generate rotation around the central vertical axis of the drivetrain, as shown below.‌

When the right mecanum wheels run in one direction while the left mecanum wheels run in the opposite direction allows for a strafing movement, as the transverse vectors add up but the longitudinal vectors cancel out.‌

Using the above concepts in tandem through varying motor power to each wheel type allows for the drivetrain to move in different, angled vectors.

Mecanum wheels, when properly set up on a drivetrain, allow for omni-directional movement. Each Mecanum Wheel Set (REV-45-1655) comes with a two right (REV-41-1656) and two left (REV-41-1657) mecanum wheels. This is determined by the direction of the leading edge of the rollers. If the rollers point left it is a left wheel and if they point right it is a right wheel.

Each side of the chassis needs one left and one right wheel. Mecanum Chassis also require four motors for operation.‌

To know if your Mecanum Wheels are properly configured look from the top down on the drivetrain. Following diagonal lines created from the angle of the rollers should form an "X" as shown above.‌

Mecanum Wheel Drivetrain Behavior

Running all four wheels in the same direction at the same speed will result in a forward/backward movement, as the longitudinal force vectors add up but the transverse vectors cancel each other out, as shown below.‌

When both wheels on one side of the drivetrain are moving in one direction while the other side is moving in the opposite direction results in stationary rotation of the drivetrain. The transverse vectors cancel out but the longitudinal vectors combine to generate rotation around the central vertical axis of the drivetrain, as shown below.‌

When the right mecanum wheels run in one direction while the left mecanum wheels run in the opposite direction allows for a strafing movement, as the transverse vectors add up but the longitudinal vectors cancel out.‌

Using the above concepts in tandem through varying motor power to each wheel type allows for the drivetrain to move in different, angled vectors.

L Beam Basics

L Beams are a structural element for small load applications or as a supporting component on a larger load application. They’re compact and lightweight and provide more strength than a Flat Beam. Use them to create a corner between plates, attach channel to extrusion, or for fastening your own creations.

Product Specs

• Material: 6063-T6 Aluminum

• Length:

• Height: 11.5mm

Mecanum wheels, when properly set up on a drivetrain, allow for omni-directional movement. Each Mecanum Wheel Set () comes with a two right (REV-41-1656) and two left (REV-41-1657) mecanum wheels. This is determined by the direction of the leading edge of the rollers. If the rollers point left it is a left wheel and if they point right it is a right wheel.

Each side of the chassis needs one left and one right wheel. Mecanum Chassis also require four motors for operation.‌

To know if your Mecanum Wheels are properly configured look from the top down on the drivetrain. Following diagonal lines created from the angle of the rollers should form an "X" as shown above.‌

Snug, Not Stuck!

When tightening a screw, firm will do. Do not keep tightening until the screw can no longer turn because this can damage structure, actuators, and eventually the screw itself. Simply secure the screw to the point that the pressure is firm.

HD Hex Pinion Pressing Guide

Needed Materials:

15mm x 45mm C Channel Basics

The uses a combination of a fixed pitch system and an extrusion system to make it easy to iterate robot designs. The Channel system overall is compatible with standard , and is designed to work seamlessly with existing and . The extrusion system has slots that allows flexible bracket positions for easy Channel to Extrusion connection.

Corrugated Plastic Sheets Basics

Corrugated plastic sheets are intended for use as a consumable flat stock to make wedges, panels, and more. This plastic is sturdy, lightweight, and easy to cut with hand tools.

Corrugated plastic sheets are a great substitute for other types of flat stock. Compared to the alternatives, this plastic is cheaper and can easily be cut to size using a box cutter when larger scale tools are unavailable. These plastic sheets come in the FTC Starter Kit V3.1 () and .

Final Assembly

Final Assembly Parts Required

Linear Motion Basics

The REV DUO 15mm Linear Motion kit is designed for use with the slots on . The Linear Motion Kit v2 () contains all the necessary hardware to build a single stage lift if a team already has an FTC Starter Kit. Items necessary for powering the linear motion system are sold separately or as part of a linear motion bundle. That being said, requirements are highly dependent on implementation so tools and actuators are excluded from the bundle. This guide is designed to build a three stage lift in two possible configurations (Cascading or Continuous). Additional materials are needed to finish the build and detailed in the Tools and Materials.

Linear motion can typically be defined as "straight line" or one-dimensional motion. Mechanisms like elevators and lifts are common examples of one-dimensional motion in robotics. The REV DUO Build System supports linear motion through the REV DUO Linear Motion Kit.

Why Supporting Motion is Important

Supporting the assemblies that move on the robot is very important. Without planning proper supports, may not be able to spin or actuators could be easily damaged.

Double Sprocket Shaft Assembly Parts Required

Double Sprocket Shaft Assembly Steps

Constraining Motion Basics

Robots need movement to accomplish goals; arms must pivot, wheels must turn, etc. However, movement that isn’t directly related to those actions can affect the accuracy and precision of the robot mechanisms. This unintended motion must be properly restricted, or constrained.

Long and thin structures can flex and deform, making it difficult to interact with objects and operate in a repeatable manner. Make use of brackets and additional Extrusion or C Channel to strengthen and constrain these structures.

How to Constrain Motion

Gears and sprockets must stay aligned or else they won’t work properly.

Keeping parts aligned on a shaft, and keeping the shaft itself from sliding out is critical for reliably working robot mechanisms. Use a combination of spacers and shaft collars to align and constrain these parts into place.

Constructing Joints

Another crucial piece to proper motion constraint is joint construction. Places where structural components, like an Extrusion and Channel, meet need to be properly supported in order to avoid structural collapse during motion.

Secure with 2 or More Brackets

In most cases joints should have at least two sides joined with brackets for strength and stability. This is especially true for plastic brackets. Commonly this involves taking two of the same kind of bracket and sandwiching the pieces of extrusion, but this can also be two different kinds of brackets such as a 90 Degree Bracket ()() and an Inside Corner Bracket ()() installed on the same corner.

Use Beveled Extrusions

When using brackets to connect extrusion, the joint will be much stronger if the end of the extrusion is beveled (cut at an angle) so that the end will sit flush with the face of the adjoining extrusion.

Different bracket angles can be combined to make structures. The joints in this example are all beveled to sit flush against the adjoining extrusion.

Ways to Create 90 Degree Joints

There are three main ways to create extrusion joints that are at 90 degrees. The most common is the 90° bracket which mates to pieces of extrusion at 90° in the same plane. The second is an inside corner bracket is functionally equivalent to the 90° bracket. The third type is called a lap joint bracket which allows two pieces of extrusion to “overlap.”

90° Bracket

Inside Corner Bracket

Lap Corner Bracket ()

M3 Hardware Basics

The REV DUO build system uses M3 hardware to connect, or fasten, brackets and structure together on a robot. Different applications require different length screws. When attaching a bracket to extrusion, shorter screws are generally required. Use longer screws to connect Control System components and other thicker materials.

Tools

We include all the tools needed to use the parts in the FTC Starter Kit. Take a moment to identify the tools below:

• 5.5mm Nut Driver ()

• 5.5mm Combination Wrench ()

• Allen Wrench Pack (1.5mm (), 2mm (), and 2.5mm Allen Wrenches)

As robots become more complex, there are additional tools, hardware, and fasteners available on the REV website:

• 5.5mm Ratcheting Combination Wrench ()

• Metric Step Drill () for drilling holes of different sizes

• Zip Ties ()

T-Slot Screws

Another type of hardware included in the kit is the T-Slot Screw (). These screws have a T-shaped head allowing them to drop in the slots of the or. This allows for modification of an existing design by adding in brackets and structure without needing access to the end of a slot.

Product Specs

• Material: Corrosion resistant zinc plated steel

• Length: 8mm

How to Use?

Simply drop the t-slot screws into the channel where you want them to go and attach the brackets or structures you want and tighten until .

Core Hex Motor Basics

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).

Pinout

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 . The image below has the pinout for the motor power and the encoder.

Product Specs

• Output Shaft: 5mm Female Hex

• Weight: 7 oz

• Voltage: 12V DC

When to Use?

The general recommendation is to use the Core Hex motor for lighter duty arms and intakes.

How to Use?

How to Mount the Core Hex Motor

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.

Servo Basics

Servo motors are a specialized kind of motor which can be controlled to move to a specific angle instead of continuously rotating like a DC motor. Instead of a hex output shaft like the DC motor, servos have an output spline. A spline is a specific groove pattern cut into the shaft which allows the rotation of the servo motor to be transmitted to the attached Aluminum Servo Horn (REV-41-1828) or Servo Adapter. Splines are like keys, so only matched types will fit together. The REV Robotics Servos all use a 25T spline pattern. If the gears or spline of the REV Robotics Smart Robot Servo (REV-41-1097) become damaged, they are replaceable using a Replacement Gear Set (REV-41-1168).

Common servo motors take a programmed input signal range and map that to an angular range. For example, for a servo with a 270° range, if the input range was from 0 to 1 then a signal input of 0 would cause the servo to turn to point -135°. For a signal input of 1, the servo would turn to +135°. Inputs between the minimum and maximum have corresponding angles evenly distributed between the minimum and maximum servo angle.

Servo Adapters

REV Robotics Servo Adapters fit 25T spline servos like the REV Robotics Smart Robot Servo. In addition to the variety pack of generic servo horns which come with the Smart Robot Servo, there are four other custom servo adapters which make using servos with the REV 15mm Building System easy.

Servo Gear Adapters convert a 25T servo into 15 tooth Delrin gear which is compatible with the other REV Robotics Plastic Gears.

Servo Shaft Adapters convert a 25T spline servo output shaft into a female 5mm hex socket. This adapter can be used to drive a hex shaft directly.

Aluminum Servo Horns have a tapped hole pattern that can be directly mounted to any of the REV Robotics gears, wheels, or sprockets with the Motion Pattern.

Aluminum Double Servo Arms () have two tapped holes that can be directly mounted to any of the REV Robotics extrusion, channel, or brackets.

Servos with the Control Hub and Expansion Hub

Teams should be aware of the number of servo motors they attach to each Hub. The Control Hub () and Expansion Hub () only can handle 5 Amps through all 6 servo ports. The maximum current a servo will draw is 2.0 Amps, called the stall current. A servo will draw the stall current when it is applying the maximum force, but it is not moving. For example, a servo can stall when a mechanism needs to hold something or a heavy object blocked the path of the servo motion.

Normally servos do not draw the maximum current, but teams do not know what might happen during matches. To protect against overdrawing the current on the Hub, only attach 2 servos to a Control Hub or Expansion Hub. Teams can safely use 4 servos: 2 servos on the Control Hub and 2 servos on the Expansion Hub.

If more power is required, consider using the REV Servo Power Module (). It is a 6V 90W power injector that enables the use of high-power RC servos in applications where a robot controller cannot provide adequate power.

Compatibility Basics

Increase the reliability of any robot system by switching from set screws to transmit motion to hex shaft. Set screws can become loose and damage your shafts over time but using a hex shaft to transmit torque doesn’t require any set screws or keys, it just simply works.

Converting part of an existing design, or using already purchased parts, with hex is easy. The simplest option is to change to the HD Hex Motor (REV-41-1291) and directly drive REV DUO Build System Wheels, or use a High Strength Hex Hub (REV-41-1147) with an existing 4-hole pattern wheel. Use a shaft color to secure the wheel from sliding off the shaft.

For a system with more shafts, the easiest way to couple between Hex and non-hex shafts is to use #25 pitch chain () because it’s common to all systems. In designs with multiple chain stages it’s possible to change any number of the shafts over to hex. The more shafts converted, the less risk of a set-screw skipping and causing a failure. Starting from the motor and then changing subsequent shafts will provide the most benefit, but any shaft that’s converted to hex will reduce a point of failure.

The HD Hex Motor is used with either a REV DUO or a Hex Hub with any 4-hole pattern sprocket. Connected by chain to the next shaft which can either be another REV Robotics based hex shaft or can connect to any existing #25 pitch chain solution a team already owns.

The High Strength Hex Hub and the Universal Hex Hub () are specifically designed to help teams use the parts they already have with the reliability and convenience of a hex drive shaft. The High Strength Hex Hub is used below to convert an AndyMark Stealth Wheel to Hex Shaft. The extended part of the High Strength Hex Hub is sized to pilot the hub into the wheel keeping it centered.

The REV DUO have mounting holes on an 8mm spacing which is compatible with other building systems. When mounting a Plastic Bracket to flat channels, turn the bracket so that the alignment ribs on the bracket face out from the channel as shone below.

Tetrix channels also use an 8mm hole spacing so almost all REV DUO brackets can mount directly to the channel. There are several ways to mount motion brackets and a structural bracket to the Tetrix Channel. The motion brackets accept a 9mm bearing so they can be used to add hex shaft to a Tetrix robot.

The 90 degree bracket above is one way to mount extrusion to Tetrix channel. A stronger method would be to miter the end of the extrusion as needed and then bolt it directly to the Tetrix channel as shown in below. Install M3 hex cap bolts and nylocs in the Tetrix channel with the heads on the side the extrusion will be installed on. Slide the extrusion into place with the bolt heads in the extrusion channel and tighten. This method will also work with Actobotics channel.

To use the REV DUO directly in place of the Tetrix bushing, it’s recommended to drill out one of the Tetrix pattern 8mm holes to 3/8” (larger than 9mm) and then install a motion bracket over the clearance hole. Depending on which 8mm hole in the Tetrix pattern is used it’s possible to match drill and add more fasteners to secure the bracket. The Delrin bearings a designed specifically to run in the nylon brackets for low friction and long wear. If using a Delrin bearing directly in the metal channel checking the bearing for wear is recommended.

Drive Shaft Assembly Parts Required

Single Sprocket Shaft Assembly Parts Required

Transmitting Motion is the act of getting motion from one part of the robot to another using shafts, sprockets, gears, etc.

Transforming Motion is the act of changing the turning force (torque) and speed. Torque and speed are inverse to each other, meaning when one increases the other decreases.

The core to transmitting motion in the REV DUO Build System is the 5mm hex (hexagonal, six sided) shape. This hex shape is incorporated into the other main motion components, such as: sprockets, gears, wheels, and shafts. are available in a number of different lengths up to 400mm, and can be cut to length if needed.

The two primary systems used to transmit motion in the FTC Starter Kit V3.1 () and are sprockets and gears.

Single Sprocket Shaft Assembly Parts Required

Bracket Basics

There are many classifications that brackets could fall into but in the REV DUO Build System there are two major groupings of brackets: motion and construction. The major distinguishing feature of motion brackets is a 9mm bearing seat to support . Construction brackets are essentially any bracket in the REV DUO Build System that does not have a bearing seat. Because the term construction bracket encompasses a broad range of REV products it can be further subdivided as structural brackets and actuator brackets.

Omni Wheel Assembly Parts Required

THREE STAGE CASCADING LIFT

Collect parts and tools for Cascading string assembly. This guide builds a four-stage lift with a surgical Tubing (REV-41-1163) return. These parts are not included in the Linear Motion Kit v2 (REV-45-1507). You will also need the completed Basic Slide Assembly.

Timing Belt and Pulley Basics

The Timing Belt and Pulley system is a pulley-based motion transmission system. Timing Belts and Pulleys transmit motion similarly to sprockets and chains. Both the Belt and the Pulley have teeth that interlock and engage with each other to drive motion.

Timing Belts and Pulleys are lighter, more compact, and more efficient at transferring motion than chains and sprockets. Belts do not stretch over time as much as chain, making re-tensioning less of an issue. In general, a timing belt and pulley system should last a full season, if properly installed. Follow through the rest of this section to learn more about the proper installation and tensioning of the REV GT2 3mm Pitch Pulley and Belt system.

Product Specs:

The REV GT2 3mm Pitch Pulleys and the GT2 3mm Pitch Belt come in various sizes to fit your needs.

All pulleys, except the 12 Tooth (), come with two ends and an inset to adjust the width of the pulley as needed to drive multiple belts.

Belt Installation

All of the GT2 3mm Pitch Pulleys, with the exception of the 12 Tooth Pulley, have flanges to keep the belt on track. This is because the belts tend to thrust to the side when in motion. It is recommended that at least one pulley in the system have flanges to keep the belt from slipping. In situations where the center distance between shafts is more than 8 times the diameter of the smaller pulley or when the drive is operating on vertical shafts, both pulleys should have flanges on both sides.

When choosing what structural aspect to use to support a pulley system, it is important that the support be rigid or capable of withstanding torsion. Any significant flex or give in the supporting structure can cause the center-to-center distance between the pulleys to change. Repercussions of a change in the center distance are slack in the belt and the belt jumping teeth.

During the installation process, ensure that supporting shafts are parallel and that pulleys are aligned.

Belts require relatively little maintenance if installed correctly, but it's always advised to run the center distance calculation to account for the installation and removal of belts.

Belt Tension

The Timing Belt should be snug when installed to ensure a longer life and less wear on the mechanism. A taut belt is not going to have the same lifespan as a snug belt, and a loose belt may jump teeth in situations where torque is high.

When working with the REV GT2 3mm Pitch Pulleys and Belts there will be some difference in pitch between the , featured on the , and the pitch of the Timing Belts. Because of the mismatched pitches, there may be limitations to getting the perfect center-to-center distance. One solution to accommodate this issue is to use a combination of M3 Standoffs () and Tensioning Bushings () to help tension the belt appropriately.

Calculating Belt Size

Determining the size of belt you need is dependent on a several factors of your mechanism. Below is the formula you will need for a 1:1 belt and pulley configuration. Here are the values you will need to find and how they work in your calculations.

RT25 Belt

• 0.0393 - This is the conversion of Centimeters to Inches so the formula can calculate tooth count in 1/4in increments.

• C2C - Center to center distance, the DUO System is on a 8mm Pitch so this value should be in mm for accurate calculations.

• 8 - This is the number of teeth in one inch of RT25 Belt multiplied by 2 for the top and bottom run of the belt.

GT2 3mm Belt

• C2C - Center to center distance, the DUO System is on a 8mm Pitch so this value should be in mm for accurate calculations.

• 2/3 - This is the number of teeth in one millimeter of GT2 Belt multiplied by 2 for the top and bottom run of the belt.

• P - This is the number of teeth in one pulley, this is to account for the teeth the belt loops around on both ends of your mechanism. Since the belt loops around half of one pulley and half of the other we can just count it as 1 whole instead of two half.

Calculating Center to Center Distance

Sometimes you will have the belt and pulleys you want to use, but not the ideal center to center distance. Use the below formula to find that ideal distance for your mechanism.

RT25 Belt

• T - This is the number of teeth in the belt.

• P - This is the number of teeth in one pulley, this is to account for the teeth the belt loops around on both ends of your mechanism. Since the belt loops around half of one pulley and half of the other we can just count it as 1 whole instead of two half.

• 3.175 - This is a conversion of half a tooth pitch to millimeters. In a RT25 belt, there is a tooth every 6.35 mm and there is a belt on top and below the pulley, so the number is divided in half to be 3.175 mm so that two teeth are added per 3.175 mm spacing.

GT2 3mm Belt

• T - This is the number of teeth in the belt.

• P - This is the number of teeth in one pulley, this is to account for the teeth the belt loops around on both ends of your mechanism. Since the belt loops around half of one pulley and half of the other we can just count it as 1 whole instead of two half.

• 1.5 - This is a conversion of half a tooth pitch to millimeters. In a GT2 3mm belt, there is a tooth every 3 mm and there is a belt on top and below the pulley, so the number is divided in half to be 1.5 mm so that two teeth are added per 1.5 mm spacing.

Collect parts for Continuous String assembly. This guide assumes you are building a four-stage lift with a Surgical Tubing (REV-41-1163) return. These parts are not included in the Linear Motion Kit v2 (REV-45-1507).

5mm Hex Shaft

The REV DUO Build System is built around a 5mm hex shaft. Using a hex shaft to transmit torque in the system removes the need for set screws, which can loosen over time and can damage shafts so that they become unusable. REV Robotics Hex Shafts are precision ground 5mm stainless steel and fit snugly in all other REV hex drive components.

Product Specs

• Material: Stainless steel (SUS303)

• OD: 5mm hex

• Length: Four Lengths, can be cut if needed

When to Use?

Use the 5mm Hex Shaft in areas where you have moving parts or need to transmit torque.

For high load applications it is recommended to use the REV precision shaft, stack multiple gears or sprockets in parallel, or use the High Strength Hex Hub Adapter () to increase strength.

How to Use?

Shaft Collars

A shaft collar is a hollow cylinder with one or more set screws which tighten towards its center and an inner dimension (ID) that is just slightly larger than the shaft it is being used on. Most standard 6mm ID shaft collars can be used on the REV Robotics 5mm hex shaft, but the REV Robotics Shaft Collar () is customized with a M3 thread so a standard hex cap bolt can be used instead of the supplied set screw.

When to Use?

Shaft collars are used to prevent lateral (sideways/sliding) movement of a shaft, or an item on the shaft. Since shaft collars are used to prevent lateral shaft movement they are often used in place of shaft spacers.

How to Use?

To use the shaft collar, slide it onto the hex shaft and rotate it until a flat side is facing the setscrew. Adjust the collar to the desired location and use a 1.5mm Allen Wrench () to tighten the included set screw snuggly against the shaft.

The REV Robotics shaft collar has a 6mm inside diameter and is customized with a M3 thread so a standard hex cap bolt can be used instead of the supplied set screw.

Spacers

for the 15mm building system have a 5mm hex center, are made of Delrin, and come in 3 lengths. Spacers are used between parts on a shaft to take up the extra space and prevent the parts from sliding on the shaft. If more than a few spacers are needed, it is typically better to use a shaft collar.

When to Use?

Spacers and shaft collars are used for the same purpose: to components on a shaft. This keeps shafts from falling out and also keeps motion components, such as gears and sprockets, aligned.

• For larger sections of exposed shaft, shaft collars are preferred because installing multiple spacers is less efficient and is more difficult to manage during robot building and maintenance.

• For shorter shaft lengths, spacers are generally more efficient.

Adapters

High Strength Hex Hub

These aluminum hubs can be mounted to any of the REV robotics hex driven motion products to increase their maximum torque. When the hex hub adapter is used on a REV product, the raised part of the hub should face away from the gear. There will be a small gap between the back of the hub and the body of the gear because of the built in spacer on the gear. Insert a shaft into both parts and then using M3x20mm and nylocs, evenly tighten the hub against the gear to ensure good alignment.

In addition to the increasing the maximum torque of REV products, the High Strength Hex Hub can be used to convert almost any of the Tetrix and AndyMark gears with the 4-hole mounting pattern to accept a 5mm hex drive shaft. Hex hub adapters allow teams to use the parts they already have with the reliability and convenience of a hex drive shaft.

Locking Motion Hub

The Locking Motion Hub () places a motion pattern on any 5mm hex shaft. Use this to connect metal sprockets to 5mm hex shaft or add strength to any REV product with the Motion Pattern. The Locking Motion Hub has a shaft collar component built-in and does not need an additional shaft collar to constrain the Hex Shaft.

Bearings Basics

The REV Robotics 15mm Extrusion Building System primarily uses plastic acetal (Delrin/POM) molded bearings. These bearings have a maximum 9mm outer diameter (OD) which fit inside the 9mm inner diameter (ID) hole in the all the motion brackets and the bearing seat of the Extended Motion Pattern.

These Delrin bearings provide stable, low friction axle support in our nylon brackets. The two materials were carefully chosen because they have a very low coefficient of friction and are also incompatible materials, meaning that they will not stick together under extreme heat. These bearings come in three varieties.

End cap bearings are closed on one end, so when these bearings are placed on both ends of a shaft and fit into motion brackets the shaft is free to rotate but is fully constrained laterally (sideways).

Short Through-bore Bearings are low profile pass-through bearings intended to seat directly into any of the motion brackets. These low-profile bearings have a 3mm contact surface which makes them flush with one side of the motion plate. Shaft collars are recommended to laterally constrain the shaft.

Long Through-bore Bearings are full depth pass-through bearings which can be used with any of the motion brackets or the bearing pillow block. Unlike the end cap bearing, because a shaft can pass though this bearing, it can be used with the bearing pillow block to have a pivot between two fixed shaft ends. Shaft collars are recommended to laterally constrain the shaft.

There are number of different bearing, shaft collar, and motion bracket combinations that are recommended. See the image below for a visual representation of some of the recommended combinations.

How to Use?

The figures in the table below show several possible combinations for bearings, motion brackets, and pillow blocks. In these figures the brackets are all depicted as facing “up” but brackets can also point “down” just as well.

Ball Bearings

The REV Robotics 15mm Extrusion Building System also uses metal ball bearings. These bearings come in two types, 8mm x 12mm Flanged Bearing () and the 5mm Hex Bearing Block (). Ball bearings provide better performance in high load or high speed applications than the Delrin bearings.

Flanged Bearing

The 8mm x 12mm Flanged Bearing has a 12mm outer diameter (OD) which press fits into the 12mm inner diameter (ID) hole of the 15mm Metal Ball Bearing Mount V2 (). The 8mm inner diameter (ID) of the bearing fits the 5mm Hex to 8mm Bearing Insert ().

5mm Hex Bearing Block

The 5mm Hex Bearing Block has a pre-pressed in 5mm Hex Bearing. The block has mounting holes designed to match the .

Basics of Chain

This drivetrain uses sprockets and chain to transmit motion from the UltraPlanetary Gearbox and Drive Shaft to the rest of the drivetrain. The figure below shows the major components of chain.

Outside Links consist of two outside plates which are connected by two pins that are pressed into each plate. The pins in the outside link go through the inside of the hollow bushings when the inner and outer links are assembled. The pins can freely rotate on the inside of the bushings.

Inside Link consist of two inside plates that are connected by two hollow bushings which are pressed into each plate. The teeth of the sprocket contact the surface of the bushings when the chain is wrapped around a sprocket.

Pitch is the distance between the centers of two adjacent pins. The REV 15mm Build System uses #25 (0.25”) chain.

To find more information about chain check out the .

Introduction to the Chain Tool

In the FTC Starter Kit is a #25 Chain Tool. This custom-designed tool allows teams to easily break and re-assemble #25 chain. The mandrel is used to push out the chain pin. If using master links, the pin can be completely removed, but the depth guide screw allows the option of partially pressing out the pin and then re-assembling without master links.

For more information on the #25 Chain Tool, see the and .

Creating the Chain Loop – Resetting Chain Method

For this drivetrain, two chain loops that are 36 links long and two chain loops that are 106 links long are needed. When counting links for chain, both the inner and outer links need to be counted. Counting the number of bushings is another way to get the correct chain length. To successfully reform chain, the total count of links must be an even number with one inner link and one outer link exposed. This allows the chain tool to press the pin back into the bushing, through an inner and outer link, reconnecting the chain. Below are the steps to use the #25 Chain Tool to reset the pin into the chain. If you would like to use master links see the for more information.

Internal Chassis Frame Assembly Parts Required

Internal Cross Member Assembly

Internal Chassis Frame Assembly

Front Grip Wheel Assembly Parts Required

Front Grip Wheel Assembly Steps

Gear Idler Assembly Parts Required

Gear Idler Assembly Steps

Creating a loop of chain requires breaking off the correct number of links by removing a specific chain pin and joining the ends together. Chain can be broken using many methods, including a Chain Tool or various steel cutting blades, like a dremel. Once you have counted the number of links necessary for your application, the chain can be joined using a master link or by replacing the chain pin.

#25 Chain Tool Basics

This custom-designed #25 Chain Tool () also commonly referred to as a "chain break" or "chain breaker", allows teams to easily break and re-assemble #25 Chain (). The mandrel is used to push out the chain pin. If using Master Links (), the pin can be completely removed, but the depth guide screw allows the option of partially pressing out the pin and then re-assembling without master links.

Basics of Chain

This drivetrain uses sprockets and chain to transmit motion from the UltraPlanetary Gearbox and Drive Shaft to the rest of the drivetrain. The figure below shows the major components of chain.

Outside Links consist of two outside plates which are connected by two pins that are pressed into each plate. The pins in the outside link go through the inside of the hollow

Traction Wheel Assembly Parts Required

Basics of Chain

This drivetrain uses sprockets and chain to transmit motion from the UltraPlanetary Gearbox and Drive Shaft to the rest of the drivetrain. The figure below shows the major components of chain.

Outside Links consist of two outside plates which are connected by two pins that are pressed into each plate. The pins in the outside link go through the inside of the hollow

Internal Chassis Frame Assembly Parts Required

Motor Basics

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.