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This section outlines the steps required to build a four-wheel, extrusion-based chain drivetrain using parts from the FTC Starter Kit V3 (REV-45-1883). This design is a good starting point. However, modification maybe required to address the specific needs of the robot being designed. This design is flexible, allowing for different wheel types depending on the overall requirements of the drive train.
The assembly of this drivetrain is broken into a few sections. This allows for a team of people to work on different tasks to complete the build quicker. Each section begins with what parts and the quantity of parts needed to complete the steps in that section. A list of required materials for all sections is listed below.
The Extrusion Chain Drivetrain is built out of the following kits:
1
4
5MM X 90MM HEX SHAFT
4
1.5MM SPACER
4
3MM SPACER
12
15MM SPACER
2
THROUGH BORE BEARING - SHORT
6
THROUGH BORE BEARING - LONG
2
SHAFT COLLAR
4
15 TOOTH #25 SPROCKET
4
20 TOOTH #25 SPROCKET
4
#25 ROLLER CHAIN - 10 FT
1
90MM OMNI WHEEL
2
90MM TRACTION WHEEL
2
15MM BEARING PILLOW BLOCK
8
15MM PLASTIC LAP CORNER BRACKET
16
15MM PLASTIC INSIDE CORNER BRACKET
8
ULTRAPLANETARY BENT MOUNTING BRACKET
2
ULTRAPLANETARY FLAT MOUNTING BRACKET
2
ULTRAPLANETARY GEARBOX KIT & HD HEX MOTOR
2
MOTION PATTERN SPACER
1
M3 X 8MM HEX CAP SCREWS - 100 PACK
2
M3 X 16MM HEX CAP SCREWS - 100 PACK
1
M3 NYLOC NUTS - 100 PACK
2
Part Number
Description
QTY.
FTC Starter Kit V3
1
Part Number
Description
QTY.
FTC Starter Kit V2
1
PART NUMBER
DESCRIPTION
QTY.
15MM EXTRUSION - 420MM
6
V2 To V3 Update Bundle
15MM EXTRUSION - 225MM
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 .
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 .
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.
Next secure the chain in place with the compression screw. Tighten until the chain cannot shift within the channel.
Note: Be careful to not overly push the pin out in the next step it will be impossible to put it back in, and a master link will be needed. As result of manufacturing tolerances, the cup point set crew may be close enough to use as a hard stop for the pin.
Screw the Pin Screw down until the pin almost touches the Cup Point Set Screw. The user should stop pushing the pin out before it leaves the back plate the outer link. Considerable pressure will be felt before the pin comes all the way out. Removing the chain from the tool to check if the pin is fully unseated from the bushing is recommended.
The final result will be the pin still partially connected to the chain (see photo as example).
Put the Inner Link bushing into the Outer Link. Align the Pin in the Compression Screw hole.
Turn the Compression Screw until the Pin is fully seated back into the chain channel.
Chain Loop Assembly Complete Repeat these steps step until you have two 36 Link Chain Loop Assemblies and two 106 Link Chain Loop Assemblies.
Unscrew the Pin Screw and Compression Screw such that they are flush with the chain channel.
Ensure the Cup Point Set Screw is fully engaged in the Chain Tool.
Insert #25 chain into the chain channel and align the desired link between the two vertical pins in the channel.
Note: Count 36 or 106 bushings from an exposed inner link.
Internal Cross Member Assembly Complete
Repeat the step above until you have four complete Internal Cross Member Assemblies.
On the opposite side of the Internal Chassis Frame from the previous two Cross Members, add another Cross Member to the assembly. Slide the Cross Member towards the middle of the two 15mm Extrusion - 420mm. Tighten the Nylock Nuts until snug.
Slide another Internal Cross Member Assembly along the 15mm Extrusion - 420mm, until the end of the Cross Member Extrusion is flush with the ends of the assembly. Tighten the Nylock Nuts until snug.
INTERNAL CHASSIS FRAME COMPLETE
Make any final adjustments to the Cross Members. The two outer Cross Members should be flush with the ends of the two 15mm Extrusion - 420mm. All Cross Members should be parallel.
15MM EXTRUSION - 225MM
4
ASSEMBLIES
PRE-LOADED INSIDE CORNER BRACKET
8
Slide the Pre-Loaded Inside Corner Bracket along a 15mm Extrusion - 225mm just far enough, so that the corner of the bracket is flush with the end of the Extrusions. Tighten the Nylock Nuts until snug.
Add another Pre-Loaded Inside Corner Bracket to the opposing side of the Extrusion from the other Inside Corner Bracket. Tighten the Nylock Nuts until snug.
Slide an Internal Cross Member between two 15mm Extrusion - 420mm until the Cross Member sits roughly towards the middle of the Extrusions. Tighten the Nylock Nuts on the Brackets until snug.
Slide another Internal Cross Member Assembly along the 15mm Extrusion - 420mm, until the end of the Cross Member Extrusion is flush with the ends of the assembly. Tighten the Nylock Nuts until snug.
Slide a 1.5mm Spacer onto the shaft.
Slide a 15mm Space onto the shaft.
Slide a 20 Tooth #25 Sprocket onto the shaft.
Slide a 3mm Spacer onto the shaft.
Slide a 90mm Traction Wheel onto the shaft.
Slide a Shaft Collar onto the shaft.
Slide a Through Bore Bearing – Short onto the shaft.
Traction Wheel Assembly Complete.
Repeat the steps above until you have two compete Traction Wheel Assemblies. Set aside for later.
1.5MM SPACER
1
3MM SPACER
3
15MM SPACER
1
THROUGH BORE BEARING - SHORT
2
SHAFT COLLAR
1
20 TOOTH #25 SPROCKET
1
90MM TRACTION WHEEL
1
Slide a Through Bore Bearing – Short onto the shaft.
Slide a 3mm Spacer onto the shaft.
15MM PLASTIC LAP CORNER BRACKET
16
15MM PLASTIC INSIDE CORNER BRACKET
8
ULTRAPLANETARY BENT MOUNTING BRACKET
2
ULTRAPLANETARY FLAT MOUNTING BRACKET
2
M3 X 8MM HEX CAP SCREWS
104
M3 NYLOC NUTS
104
Take a bracket and finger start one Hex Cap Screw and Nyloc Nut per hole.
PRE-LOADED BRACKET COMPELTE
Repeat this step until you have twelve Pre-Loaded Brackets.
Take a bracket and finger start one Hex Cap Screw and Nyloc Nut per hole.
PRE-LOADED BRACKET COMPELTE
Repeat this step until you have eight Pre-Loaded Brackets.
Take a bracket and finger start one Hex Cap Screw and Nyloc Nut per hole.
PRE-LOADED BRACKET COMPELTE
Repeat this step until you have eight Pre-Loaded Brackets.
Take a bracket and finger start one Hex Cap Screw and Nyloc Nut per hole.
PRE-LOADED BRACKET COMPELTE
Repeat this step until you have two Pre-Loaded Brackets.
Take a bracket and finger start one Hex Cap Screw and Nyloc Nut per hole.
PRE-LOADED BRACKET COMPELTE
Repeat this step until you have two Pre-Loaded Brackets.
PART NUMBER
DESCRIPTION
QTY.
15MM BEARING PILLOW BLOCK
8
The side of the bracket with “” must have the Hex Cap Screw head.
The side of the bracket with “” must have the Hex Cap Screw head.
The side of the bracket with “” must have the Hex Cap Screw head.
Slide a 15 Tooth #25 Sprocket onto the shaft.
Slide a 3mm Spacer onto the shaft.
Slide a 20 Tooth #25 Sprocket onto the shaft.
Slide a Shaft Collar onto the shaft.
Slide the 90mm Omni Wheel onto the shaft.
Slide a 3mm Spacer onto the shaft.
Slide a 3mm Spacer onto the shaft.
Slide a Through Bore Bearing – Long onto the shaft.
Repeat the steps above until you have two compete Traction Wheel Assemblies. Set aside for later.
1.5MM SPACER
1
3MM SPACER
3
THROUGH BORE BEARING - SHORT
1
THROUGH BORE BEARING - LONG
1
SHAFT COLLAR
1
15 TOOTH #25 SPROCKET
1
20 TOOTH #25 SPROCKET
1
90MM OMNI WHEEL
1
Slide a Through Bore Bearing – Short onto the shaft.
Slide a 1.5mm Spacer onto the shaft.
The FTC Starter Kit comes with two of the UltraPlanetary Gearbox Kits with HD Hex Motors. This is an entry point into using the REV UltraPlanetary System. There are three UltraPlanetary Cartridges supporting seven different final gear reductions ranging from nominally 3:1 to 60:1. This allows for the right amount of torque for the application at hand. The motor provided already has the pinion gear pressed onto it making assembly of gearboxes easier.
When getting started with this drivetrain, it is recommended to use a nominal 20:1 Gear Ratio. This uses the UltraPlanetary 5:1 Cartridge and the UltraPlanetary 4:1 Cartridge. For more information on all gear ratio options, load ratings, and more, see the UltraPlanetary Gearbox User’s Manual on revrobotics.com.
ULTRAPLANETARY GEARBOX KIT & HD HEX MOTOR
1
M3 X 8MM HEX CAP SCREWS
4
M3 X 16MM HEX CAP SCREWS
3
15 TOOTH #25 SPROCKET
1
MOTION PATTERN SPACER
1
ASSEMBLIES
PRE-LOADED ULTRAPLANETARY FLAT MOUNTING BRACKET
1
PRE-LOADED ULTRAPLANETARY BENT MOUNTING BRACKET
1
PARTS WITHIN THE ULTRAPLANETARY GEARBOX KIT
PART NUMBER
DESCRIPTION
QTY.
HD HEX MOTOR
1
Attach the UltraPlanetary Mounting Plate to the HD Hex Motor using two 8mm Button Head Screws.
Note: Use the 2mm Allen Key to tighten these screws.
Seat the UltraPlanetary 5:1 Cartridge onto the input pinon.
Note: Placing a finger on the output of the 5:1 Cartridge and turning it helps for placement.
PART NUMBER
DESCRIPTION
QTY.
ASSEMBLIES
PRE-LOADED LAP CORNER BRACKET
16
PRE-LOADED BEARING PILLOW BLOCK
8
TRACTION WHEEL ASSEMBLY
2
OMNI WHEEL ASSEMBLY
2
ULTRAPLANETARY GEARBOX ASSEMBLY
2
INTERNAL CHASSIS FRAME
1
106 LINK #25 CHAIN LOOP
2
36 LINK #25 CHAIN LOOP
2
Slide an UltraPlanetary Gearbox Assembly along one of the 15mm Extrusion - 420mm, until it sits just past the second Cross Member. Ensure that the pre-loaded M3 x 8mm Screws on both brackets are interlocked with the Extrusion slots. Tighten the Nylock Nuts until snug.
Slide the second UltraPlanetary Gearbox Assembly along the Chassis Frame, so that the motor sits parallel to the motor from Step 6. Tighten the Nylock Nuts until snug.
PART NUMBER
DESCRIPTION
QTY.
15MM EXTRUSION - 420MM
4
ULTRAPLANETARY PINION GEAR (ON HD HEX MOTOR)
1
ULTRAPLANETARY MOUNTING PLATE
1
ULTRAPLANETARY CARTRIDGE 4:1
1
ULTRAPLANETARY CARTRIDGE 5:1
1
ULTRAPLANETARY OUTPUT STAGE
1
M3 X 30MM CAP HEAD SCREW
6
M3 X 8MM BUTTON HEAD SCREW
2
Seat the UltraPlanetary 4:1 Cartridge onto the UltraPlanetary 5:1 Cartridge.
Note: Placing a finger on the output of the 4:1 Cartridge and turning it helps for placement.
Seat the UltraPlanetary Output Stage onto the UltraPlanetary 4:1 Cartridge.
Note: Placing a finger on the output of the Output Cartridge and turning it helps for placement.
Insert six of the 30mm Cap Head Screws into the holes in the outer ring off the Output Cartridge.
Tighten these screws down until they are snug not tight using a 2.5mm allen wrench.
Note: The 30mm length is the 2nd longest screw provided with the UltraPlanetary Gearbox Kit.
Attach the Pre-Loaded UltraPlanetary Flat Mounting Bracket and the Pre-Loaded UltraPlanetary Bent Mounting Bracket to the Output Cartridge using three M3 x 8mm Hex Head Screws. Tighten Screws until they are snug not tight.
Line up a 15 Tooth #25 Sprocket and a motion pattern spacer with the holes on the UltraPlanetary Output Stage. Use three M3 x 35mm Hex Cap Screws to attach the Sprocket and Spacer to the ighten screws until snug.
Use three M3 x 35mm Hex Cap Screws to attach the Sprocket and Spacer to the ighten screws until snug.
Add two Pre-Loaded Lap Corner Brackets to the Internal Chassis Frame as shown. Tighten Nylock Nuts until snug.
Note: The outer corner of the Lap Corner Brackets should be in line with the nearby Inside Corner Bracket.
Add two Pre-Loaded Lap Corner Brackets to the Internal Chassis Frame as shown. Tighten Nylock Nuts until snug.
Note: The edge of the Lap Corner Brackets should be flush with the end of the Extrusion.
Slide a 15mm Extrusion – 420mm into the Pre-Loaded Brackets until the Extrusion is roughly central to the center of the Internal Chassis Frame center.
Add two Pre-Loaded Lap Corner Brackets to the 15mm Extrusion – 420mm as shown. Tighten Nylock Nuts until snug.
Add two Pre-Loaded Lap Corner Brackets to the 15mm Extrusion – 420mm as shown. Tighten Nylock Nuts until snug.
Note: The edge of the Lap Corner Brackets should be flush with the end of the Extrusion and the Lap Corner Brackets from the previous step. Adjust the Lap Corner Brackets from the previous step if this is not the case.
Slide two 15mm Extrusion – 420mm into the Pre-Loaded Lap Corner Brackets as shown. The ends of the Extrusions should be flush with the edge of the perpendicular Extrusion. Tighten Nylock Nuts until snug.
Add two Pre-Loaded Bearing Pillow Blocks to the Omni Wheel Assembly.
Add the 106 Link Chain Loop to the 20 Tooth #25 Sprocket on the Omni Wheel assembly. Add the 36 Link Chain Loop to the 15 Tooth #25 Sprocket on the Omni Wheel Assembly.
Slide the Omni Wheel Assembly onto the bottom side of the Chassis as shown above. Do Not tighten the Nylock Nuts on the Brackets.
Add two Pre-Loaded Bearing Pillow Blocks to the Traction Wheel Assembly.
Add the Traction Wheel Assembly to the 106 Link Chain Loop attached to the Omni Wheel Assembly, so that the Chain is hooked on the 20 Tooth # 25 Sprocket. Slide the Traction Wheel Assembly into the Extrusions on the bottom side of the Chassis.
Slide the Wheel and Chain Assembly along the bottom of the chassis until the Omni Wheel is behind the UltraPlanetary Gearbox Assembly. Hook the 36 Link Chain Loop over the 15 Tooth #25 Sprocket on the UltraPlanetary Gearbox Assembly.
Note: Adjust the Wheel and Chain Assembly until both Chain Loops are appropriately tensioned. Once adjusted tighten the Nylock Nuts on the Bearing Pillow Blocks until snug.
Repeat the previous steps until both side of the chassis have the wheel and chain assembly.
Add four Pre-Loaded Lap Corner Brackets on to the ends of the four exposed ends of Extrusion. Tighten the Nylock Nuts.
Note: The brackets should be approximately 15mm (the width of an Extrusion) from the ends of the Extrusion.
Add four Pre-Loaded Lap Corner Brackets on to the ends of the four exposed ends of Extrusion. Tighten the Nylock Nuts.
Note: The brackets should be approximately 15mm (the width of an Extrusion) from the ends of the Extrusion.
Slide a 15mm Extrusion – 420mm into the Pre-Loaded Brackets until the Extrusion is through all the Brackets. Tighten the Nylock Nuts.
Drivetrain Complete
