Eccentric Weight G-Force Calculator

Calculate the G-force produced by rotating eccentric (unbalanced) weights - the half-moon shaped masses used in vibrating screens, shale shakers, and vibratory equipment. Works for both single and counter-rotating configurations.

How Counter-Rotating Eccentric Weights Create Linear Vibration

Half-moon weights (semi-circular masses) rotate on parallel shafts. When they counter-rotate (spin in opposite directions but synchronized), the horizontal force components cancel out, leaving only vertical force - creating linear vibration. This is exactly how shale shakers work.

Configuration

⟲⟳

Counter-Rotating

Two weights, opposite spin (linear motion)

⟳

Single Eccentric

One weight (circular motion)

Weight Parameters

Eccentric Mass (kg) — mass of ONE half-moon weight

Eccentricity (mm) — distance from shaft to center of mass

For a half-moon weight, this is approximately 4r/3π from the shaft (about 42% of outer radius)

Rotational Speed (RPM)

Total Vibrating Mass (kg) — screen + frame + material

Number of Weight Pairs

Most shale shakers use 2 pairs (4 weights)

4.52 G

Peak Acceleration

OPTIMAL RANGE

Total Force

Force per Weight

Frequency

Angular Velocity

G-Force Guidelines

Application	Typical G	RPM Range
Shale Shakers	4 – 8 G	900 – 1800
Scalping Screens	3 – 5 G	700 – 1000
Fine Screening	5 – 7 G	1000 – 1500
Dewatering	4 – 6 G	800 – 1200
Vibratory Feeders	1 – 3 G	600 – 1200
Compaction	10 – 30 G	2000 – 3600

Formulas Used

F = m × ω² × r

Centrifugal force per weight (m=mass, ω=angular velocity, r=eccentricity)

G = (n × F) / (M × g)

G-force on system (n=number of weights, M=total mass, g=9.81)

ω = 2π × RPM / 60

Convert RPM to radians per second