Embedded Files
I chose these three mechanisms from the video:
Cam Mechanism
Geneva Mechanism
Four-Bar Linkage
I modeled all three in Fusion 360, created a motion set, 3D printed, and assembled them. The 3D parts turn manually.
CAM & Follower Mechanism
CAM & Follower Mechanism
A cam mechanism is a mechanism that converts rotary motion into linear or oscillating motion using two main parts: the cam and the follower.
The cam is a rotating or sliding component with a specially shaped profile. As the cam turns, its shape determines when and how much motion is possible. Because the cam’s profile is not meant to be circular, different points on its surface push against the follower at different distances from the center of rotation.
The follower is the component that rests against the cam’s surface and responds to its motion. As the cam rotates, the follower moves up and down, side to side, or pivots, depending on the design. The follower is often guided by a track or constrained to move in one direction, and it may be kept in contact with the cam by gravity, a spring, or mechanical linkage.
Together, the cam and follower allow precise control over timing, displacement, and motion patterns, which is why cam mechanisms are commonly used in engines, pumps, and automated machinery where specific sequences of movement are required.
CAD Design
CAD Design
made a 10 mm diameter 2 mm height
printed it out to compare how it might fit with a spring
It didn't fit so I'm glad I tested it. The blocker was also not thick enough. I changed the larger cylinder to 5 mm diameter and 80 mm height. The smaller cylinder was changed to a 12 mm diameter. I also decided to make a rounded head to guide the plastic along the turning piece:
made a spline form
revolved the spline form 360 degrees
started the body with a 150 x 50mm rectangle
two rectangles with width 7 mm
on one side, made a circle with diameter 9 mm
extruded them 15 mm
centered circles and cut them through
9 mm circle
cut the circle
printed these designs out along with some test cylinders to test which tolerance is the best fit
8 mm turned out to be the best fit
filleted the edges of the rectangular prisms
designed a stand so the mechanism is upright
finished design for the main structure
spline form design for the cam
mirrored the spline form
extruded the design by 10 mm
3 mm high cylinder for gap
15 mm high cylinder as handle
another piece secures the back
Motion Simulation
Motion Simulation
In animating, I faced an issue of my follower, being a sliding joint, going through the cam mechanism as it went down. I found this tutorial to learn how to set limits to animate my mechanism.
I had to right click on the joint and go to Edit Motion Limits and select the Rest option. I played around with the values and ended with a resting -6.5 and maximum 50 mm.
I also had to make a motion set and selected the cam and follower components.
CAMbetter.movfinal motion simulation
CAMbetterzoom.movbetter zoom in of simulation
Prototyping and Testing
Prototyping and Testing
I printed out the main structure
side view
view of centered hole placement
IMG_3512.movThe initial printed design (left) had stability issues because the two securing rectangles were positioned too close. This allowed the follower to shift in the horizontal direction, preventing a straight path. So, I redesigned the components by separating them more, allowing more contact along the follower (right). This change improved stability and resulted in much straighter vertical motion.
IMG_3515.movApplication
Application
A cam mechanism converts rotational motion into linear or oscillating motion through direct contact between a cam profile and a follower. The follower's displacement, velocity, and acceleration are controlled by the cam’s geometry. This allows enginers to design specific motion. Thus, cams are used in systems where timing and synchronization are involved. For example, with internal combustion engines, camshafts control valve lift and duration, directly affecting engine efficiency. Cam mechanisms are also used in automated manufacturing equipment and mechanical presses, where there is repeated motion.
Geneva Mechanism
Geneva Mechanism
I followed this tutorial to create a spherical Geneva Mechanism.
CAD Design
CAD Design
circle w diameter 122 mm
drew a line coincident with the origin
used revolve tool to create a hemisphere
shelled with a 6 mm thickness
sketch on the face of the top
extruded it to the extent of cutting through all
projected two edges
drew a form that is the image of the base
revolved it 360 degrees
center-center slot, 44 mm length 8 mm diam
extrude cut it through all one side
constructed a plane at angle 45 degrees
constructed a sketch on that plane, projected the edge that is the brim of the cup, and made a 28 radius semicircle using center point arc
extruded and cut through all again
used the circular pattern tool on both cutouts
45 degrees from the horizontal construction line, another slot 88 mm length, 16mm radius
then a line that is 8mm distance
extruded 8 mm to object
then the semicircle extrudes 122 mm height
made a sketch on the inner rectangle of the recent extrusion, the centerpoint of a 6mm radius circle being the origin
extrude by 16 mm
started a sketch on the new extruded circular face
projected the circle edge and the corner point of the semi-circle cutout
made a circle that is coincident with the corner of the cutout
offset it 6 mm
drew a centerline
extruded it all -6 mm as a new component
join extrusion 22 mm
constrained the sketch
extruded the sketch: symmetric, 10 mm, join
10 mm fillet on each edge
drew a 16 mm diameter circle on the new face
26 mm extrusion of the circle
Motion Simulation
Motion Simulation
the final finished spherical geneva mechanism
pinned the base and seperated them
joined the two circle edges, revolutely
Also joined the cylinder under the turning component revolutely with the base of the mechanism.
Circular_Geneva_Front.movFrontal View
Selected Assemble, Enable All Contact. Then, I selected Revolute 1 under Relationships > Joints, then selected Animate Joint Relationship.
Circular_Geneva_Side.mov3/4 view
Prototyping and Testing
Prototyping and Testing
printing setup
printed pieces assembled
IMG_3580.movvideo of mechanism working in real life
Application
Application
The Geneva mechanism is designed to transform continuous rotational input into intermittent motion with angular increments. A rotating drive wheel engages slots in the Geneva wheel, advancing it by a fixed angle before disengaging and allowing a locking surface to hold the wheel stationary. This design allows accurate positioning while keeping the system relatively simple. In real-world engineering, Geneva mechanisms are commonly used in indexing tables, film transport systems, and mechanical timing devices such as watches.
Four-Bar Linkage
Four-Bar Linkage
CAD Design
CAD Design
made 4 center-to-center slots
150 mm length, 10 mm diameter
175 mm length, 10 mm diameter
200 mm length, 10 mm diameter
200 mm length, 10 mm diameter
Each were extruded 5 mm high separately. With each extrusion, they were made to be a new component. This is important because when assembling it, they can each individually be assembled and have their own joint movement.
I also designed a flat base for the linkages to be able to slide on. I marked the circle the crank goes around and arc which the follower creates. I then offset both shapes by 3 mm.
I extruded those lines by -5 mm, creating grooves in the base. These guidelines make it clear the path of the links. Since its a crank-rocker mechanism, one goes 360 degrees, the other goes an arc.
Motion Simulation
Motion Simulation
I pinned (right-click component > pin) the 150 mm component because it is my ground
I just joined all four together links with the joints tool. all of them revolute
4_Bar.movafter that, I was able to move the mechanism around by dragging any link other than ground
4_Bar_Based.movanimation of the linkage movement superimposed on my sketch
4_Bar_Solidbase.movanimation on the finished bottom plate piece to show angle of motion
Prototyping and Testing
Prototyping and Testing
I originally had issues with its movement, but Mr. Budzichowski helped me realize that I should remove the ground, which was obstructing the path of the coupler. Then, I redesigned and fitted new linkages.
IMG_3571.movCAM3bar.movI also remade the model in suit, but in order for the linkages to go in the right direction, you have to select animate joint relationships on joint 10, specifically
Application
Application
A four-bar linkage consists of four rigid links connected by revolute joints, forming a closed kinematic chain capable of converting rotational motion into oscillatory or more complex planar motion. By adjusting link lengths and the placement of pivots, engineers can control the resulting motion. In a common crank–rocker configuration (what I made), one link rotates continuously through 360 degrees while the output link is constrained to oscillate over a limited arc. This allows continuous motor input to produce controlled back-and-forth motion, a behavior that is especially useful in real-world systems. In genereal, this adaptability makes four-bar linkages very important for mechanical engineering design. They are widely used in automotive suspension systems, windshield wipers, and robotic mechanisms, where smooth and predictable motion is essential.
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