Input: green shaft to which a cam and a crank are fixed.
The crank traces a heart-shaped curve (in pink).
Angular position between the Archimedean cam and crank must be as shown in the video (0 deg.) or 90 deg.
The cam profile consists of 4 sections. Each one is an Archimedean spiral of equation in polar coordinate system:
ρ = a + (B/360)φ
a: smallest radius of the profile
B: spiral parameter
φ: rotation angle of the cam
If the profile is a concentric circle, the crank traces a circle.
Its equation:
x = Rcos(φ)
y = Rsin(φ)
R: the crank radius.
However the cam moves the bearing and affects the y value so equation of the heart curve in polar coordinate system is
x = Rcos(φ)
y = Rsin(φ) +/- (B/360)φDisadvantage: the input shaft bearing is not stationary.
The mechanism can be used for cake decoration.