Spring 2016: 3DoT David Rapid Joint Connection (Between Gear and Leg)
BY: Andrew Saprid ( Manufacturing Engineer)
Introduction:
The joint implemented will be lightweight and easier for the motor to operate the legs of the 3Dot David as it completes its mission. In addition, it must be able to rotate the legs for free movement.
Related requirements
Level 2 system requirements follow:
- The 3DoT David shall use two micro motors for the movement system of the robot.
Printing a joint in Solid-works
A joint is made in solidworks to be 3D printed. The problem with this design is the shape of the joint may interfere with where the screw, or nail is going to be placed at through the center hole of the gear. It would require a lot of sanding.
Tube from a mechanical pencil as a joint
Another solution was to use a tube that holds the leads inside of the mechanical pencil as a joint. The tube had to be sanded in order for it to fit inside the hole of the gears. However, the tube gets stuck on the gear, so the tube does not rotate on the gear. A lot of labor would be put into for sanding those six tubes as the joints.
A Joint in one of the white gear bag
We found a joint solution in one of the parts in the white gear bag. This joint has a length of about .939 centimeters. It’s diameter on the bottom of the joint is about .487 centimeters. The diameter of the hole on the bottom is about .196 centimeters, which the screw will go into the hole.
We went to Jk electronics to buy screws and washers to create the joint. The screws cost $2.49, and the washers cost $3.75. The hole of the diameter is about .287 centimeters. The diameter of the screw is about 0.2 centimeters. The length of the screw is 0.753 centimeters.
The joint is then assembled together. The washer with the screw is placed on the bottom side of the gear. That way the joint does not come out of the gear as the joint rotates in a 360 degree motion. This would not require any hard labor of sanding to fit it into the gears, saving a lot of time.
Conclusion
The part in the white gear bag will be used as a joint as it was able to rotate on the red gear.