Explore the mechanics of vintage postal weighing with the MOC-202559 Bilateral Mechanical Letter Scale Building Blocks. Designed and authorized by Nico71, this 288-piece model recreates a classic dual-scale letter balance inspired by antique Columbus Maul-style postal scales.

Operating entirely through connecting rods, levers, pendulums, pointers, and counterweights, the model requires no motors or electronics. Place a letter or small object on the upper tray and the mechanism responds mechanically, translating its weight into movement across two different measuring ranges.

Fully Mechanical Weighing System

The upper tray is connected to two symmetrical pendulum arms through a system of connecting rods.

As weight is added, the pendulum sides move farther apart. This movement is transferred directly to the pointers, allowing the object’s weight to be read from the scales.

Dual Measuring Ranges

Two separate pointers provide different measurement ranges:

• Lower scale: approximately 0–80 g
• Upper scale: approximately 70–175 g

The lower range provides finer movement for lighter objects, while the upper range extends the weighing capacity for heavier letters and small items.

Fine Low-Weight Measurement

The lower pointer is positioned farther from the pendulum’s center of rotation, with its linkage geometry arranged closer to a right angle.

This produces greater pointer movement for small changes in weight, creating a more sensitive and comparatively linear scale for lighter objects.

Extended High-Weight Range

The upper pointer uses a shorter effective radius and different linkage angle, resulting in less movement as the load increases.

This allows the mechanism to cover a larger weight range while preserving the balanced bilateral layout of the scale.

Visible Linkage Mechanics

The open design makes it easy to observe how tray movement is transformed through rods and levers into pointer displacement, turning a simple weighing action into a hands-on mechanical demonstration.

Vintage Desk Display

Inspired by historical postal equipment, the tall symmetrical frame and twin dials give the model the appearance of an antique scientific instrument.

At approximately 20 × 10 × 28 cm, it works well as a compact desk or shelf display.

From the Designer

Nico71 developed MOC-202559 as a fully mechanical recreation of a bilateral letter scale, drawing inspiration from vintage Columbus Maul weighing instruments.

The challenge was to create two useful measuring ranges while maintaining the symmetry required for the mechanism to function correctly. By adjusting the distance and angle of each linkage relative to the pendulum axis, the design produces a sensitive lower scale for lighter objects and a broader upper scale for heavier ones.

A Functional Mechanical Desk Model

With 288 pieces, two weighing ranges, visible rod-and-lever mechanisms, and no need for electric power, MOC-202559 offers an unusual build for mechanical-engineering fans, antique instrument collectors, and anyone interested in functional desktop models.