How To Build a Chain Drive 4WD Robot - IG52 DB4
Contents
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These videos will walk you through building our IG52 DB4 4WD Robot but these can also be used to build the following robots as well:
Please note that this platform is for ages 16 and requires some mechanical and electrical skills as well as some basic hand tools. This is a professional development robot platform with a robust welded chassis and quality components. Each wheel is supported by two durable double sealed bearings which allow the robot to hold a lot of weight. The chassis is made of 1/8 thick aluminum, which is easy to drill into, allowing this platform to be customized to fill your requirements. If you do not feel comfortable assembling this platform, we can assemble it for you for an extra charge. If you have questions feel free to Contact Us.
Part 1 (Steps 1-3)
Step 1: Mount motors to chassis
The chassis has a pattern of slots where each motor will mount. Prep all the M5 screws with a washer and Loctite. Place a motor plate between motor and chassis and insert screws through the chassis and motor plate into the motor. Screw in most of the way but make sure you can still slide the motors back and forth in the slots.
Step 2: Insert bearings
There are eight bearing holes at the corners of the chassis where the wheels will mount. Press them in by hand.
Step 3: Mount Sprockets to Motors
The wheels in this robot are chain driven so we will need to mount sprockets to the motor shafts and later to the axles. We use #25 15 tooth sprockets with 12mm D-bore for the motors. Before mounting sprockets, approximate how far out on the shaft the teeth need to be to line up with mating sprocket on the axle. Unscrew set screws and place sprockets on the motor shaft. Tighten in place using Loctite.
Tools used in this video:
- Phillips Screwdriver
- Blue Loctite
- 1/8" Allen wrench
- Pliers
- Rag
How to Size and Cut Roller Chain
Measuring the chain
To measure the chain simply place the chain in the sprockets and mark where you would make the connection. Note that to connect the chain a connecting link will need to be put in that will take the place of another link. So you would need to remove the link that you marked and replace it with the connecting link.
Cutting the chain
There are many different tools you can use to cut the chain. In the video, we use an angle grinder but other tools like a Dremel or a hand file will also work. To cut the chain you want to file down the rivets that fasten the links. Once the rivets are filed down enough, you can remove the link you marked and replace it with the connecting link.
Installing the chain
Now that you have your chain cut to the size you can connect the two ends with the connecting link and install it. Note that one side of the connecting link will protrude from the chain farther than the other side. You will want to orient the chain so that this protrusion on whichever side has more clearance.
Tools used in this video:
- Sharpie
- Angle grinder
- Screwdriver
- 1/8" Allen Wrench
Part 2 (Steps 4-5)
Step 4: Couple motors to wheel shafts
In this video, we are also chain coupling the wheels together on each side of the robot for better off road performance. The wheels are coupled together using 15 tooth sprockets while the motors are coupled to 21 tooth sprockets. Move the motors in the slots so they are all the way toward the wheel axle they couple to. Slide a lock collar onto the axle and then slide the axle through the first bearing. If you are chain coupling wheels, slide a 15 tooth sprocket (with key) onto the axle first and then slide the 21 tooth sprocket (also with key) on so it aligns with the motor sprocket. Orient both hubs toward the center of the chassis to allow room for the chain. Pre-assemble chain with connecting link and wrap around the 21 tooth sprocket and the motor sprocket. Finally, slide the axle through the second bearing and place a lock collar so that it is flush with the end of the shaft. Tighten the set screws on the lock collars. Tension chain by moving the motor away from the axle in slots and tightening the motor screws.
Step 5: Couple front and rear axles (optional)
Fish chain through the chassis and around both 14 tooth sprockets on the front and rear axles. Insert connecting link between two chain ends. This will chain will need to be tensioned. We use a round plastic tensioning block that pushes down on the chain.
Tools used in this video:
- Screwdriver
- 1/8" Allen Wrench
- Loctite
Part 3 (Steps 6-7)
Step 6: Fix sprockets to axles
Note: Newer versions of the IG52 robot use keyed shafts so this step is no longer necessary.
In this step we will be drilling a dent in the axle to make a secure connection between the sprocket and the axle. The dent should be just deep enough to fit the bottom of the set screw (the chamfered edge underneath the threads). Make sure the set screws in lock collars are secure so that the axle cannot slide back and forth in the bearings. Also, make sure the teeth on all mating sprockets are lined up. Start by tightening one of the set screws on a sprocket and then remove the other. Use a 5/32" drill bit to center dent in set screw hole but be careful not to damage the threads. Change to the 13/64 drill bit to finish dent. Insert set screw with thread lock and tighten it into the dent. Remove the other set screw to place thread lock and secure it again. Repeat process for all sprockets on the axles.
Step 7: Mount wheels to axles
Remove all hardware from the wheels and mount wheel to the axle. Make sure all screws are in place before tightening nuts all the way. Also, make sure that the valve stems are on the outside of the robot. Before driving the robot, make sure you inflate the tires. Failure to do so may cause the wheel hub to spin inside the tire and break the valve stems.
Tools used in this video:
- Socket Wrench
- 12mm Socket
- 14mm Socket
- Screwdriver
Wiring and Final Assembly
For help wiring and completing assembly see our Schematics and Robot Electrical Power
pages.