Hello! Are you ready to build a strong, fast, and durable robot? It is much simpler than you think, it is just a combination of building a gear train and screwing in wheels, bars, and other parts!
Step 1: Gather Parts : Basic Parts
(4) Chassis rails
(1) 5-hole angle bar
(8) 8-32 x1/4" ( 6.4 mm )screw
(1) Chassis bumper
(12) Keps nuts
(2) Flat bearing
Step 2: How to Build the Robot Frame
Right now, you are going to build the frame of the robot, this is the basic design of the robot. This step is important because all additional parts and additions to the robot are attached through the frame of the bot. The frame acts as the foundation of the robot.
-Screw the 4 chassis rails onto the bumper (on the first, fourth, twelfth and fifteenth holes).
- Screw the other end of the 4 chassis rails onto the 15-hole angle bar (make sure the angle bar and bumper are parallel).
Step 3: Gather Parts : Specified for Gear Train
Materials for the gear train:
- (6) 36 tooth gears (3 for each side)
- (2) 12 tooth gears (1 for each side)
- (4) 10cm wheels (2 for each side)
- (8) Square bars (4 for each side)
- (12) Locks nuts (6 for each side)
- (14) Keps nuts (7 for each side)
- (18) Flat bearing (9 for each side)
- (18) Spacers (9 for each side)
- (28) 1/2" screws (14 for each side)
Step 4: How to Build the Gear Train
To build this complicated gear train you need to take the weight the bot will carry into consideration, this is why you will construct a 3:1:1:1 ratio, this will provide a high torque and sustainable speed.
This is how you make the gear train:
- line up the flat bearings with where you will insert your square bars (2 flat bearing parallel to each other)
- screw the flat bearings into the frame of the robot using 1/2" screws and keps nuts
- insert a 7" square bar through two chassis rails and one of the 36 tooth gears
- do the same thing for the next 36 tooth gear with a 3" square bar
- then another 7" square bar for the next 36 tooth gear
- then a 3" square bar for the 12 tooth gear
- for every gear the order of parts the square bar goes through is: spacer, locks nut, gear.
(replicate for other side)
Step 5: Test the Gear Train (ratio)
If you have constructed the gear train correctly there should be minimal friction between the gears and the robot should run straight forward. The gear ration on each side of the train is 3:1:1:1, the "3" is the 12 tooth gear. Having the 3:1 ratio gives the robot torque on a wheel, and the speed is upheld by the 1:1 ratio on the other wheel.
Input RPM : 117.8 RPM
Output RPM : 39.3 RPM
Theoretical Speed : 20.6 cm/s
Actual Speed : 20.4 cm/s
Input Torque : 1.67 NxM
Output Torque : 5.01 NxM
Your result should look like this the video above...
Step 6: Gather Parts : Sled
To build the sled, you need to use sturdy parts because this is where you will be carrying your weights.
To parts you'll need are:
- (1) 10-hole bars
- (1) Flat plate
- (2) Threaded beams
- (12) Keps nuts
- (14) 1/2"screws
- (5) Bearing blocks
Step 7: How to Build the Sled
To construct the sled you will need to attach the 10-hole bar to the flat plate by screwing in 1/2" screws onto the flat plate and on the opposite end of the 10-hole bar. The 10-hole bar acts as a bridge between the robot and the sled.
You will then screw in the bearing blocks with the 1/2" screws and keps nuts. The bearing blocks should be screwed in UNDER the flat plate so that they act as 5 different points to distribute the weights.
Then you screw in the 2 threaded beams and position them not too far from each other. The threaded beams act as a hook or slot to put the weights on.
If everything is done correctly, your sled should look like the one above!
Step 8: Gather Materials : to Weight the Front End of the Robot
To weigh down the front of the robot you will need the following materials:
- (2) Bumpers
- (6) Keps nuts
- (6) 1/2" screws
- About (20) 10-hole bars
Step 9: How to Weigh Down the Robot
At this point your robot should be able to easily drive, but there is still something to add. If you put weight on the sled, the robot can handle it, but the more weight on the sled, the more the robot tips back, lifting its front wheels off the ground.
To be able to keep the front wheels down will increase the speed and the amount of weight the robot can pull because then all 4 wheels will be used.
To keep the front wheels to stay down, we are going to screw on a bumper to the front of the robot and screw on another bumper on top of the newly added one. The front of the robot will now have a rectangular prism. You are then going to fill the rectangular prism with any type of metal (preferably 10-hole bars). Filling the rectangular prism will weigh down the front of the robot and make the robot much more efficient.
Step 10: Test the Robot
At this point you have nothing left to do but watch your robot work its magic!
Do not be discouraged if your first run does not go as planned, it is likely that you will have to make minor modifications to the robot, but nothing too serious, for example; changing the weight of the front end of the bot, or switching out your batteries.
Besides those minor modifications you should be good to go!