Frameless Scale

Finished rails (load cell mounts). Two go under the hive, one on each side.

Goals:

• Parts cost under $100 and are readily available.
• Low thermal drift and creep.
• Low power consumption.
• Automatically resumes operation after power failure.
• Can be built by 15 year old student (9th grader) using hand tools.
• No soldering.
• No lethal voltages.

End view with end cap closure strip removed.

Design Features

• No frame: no welding, no bending.
• Load cells are mounted in metal strut readily available from electrical or industrial suppliers in aluminum. galvanized or painted steel.
• Only straight cuts and drilled holes.
• All electrical connections are made with crimp plugs or terminal blocks.

Material List

A detailed Parts List with part numbers, suppliers and prices is available in pdf.

Parts Detail

Strut is available from different manufacturers with different brand names: Unistrut, Superstrut, etc. It is available in galvanized steel, aluminum, and fiberglass. Closure strips are available in steel, aluminum or plastic.

If the scale will be shipped via UPS or USPS, even though the aluminum is more expensive, it will be cheaper when shipping expenses are considered.

Block Diagram

Block Diagram

HX711 with screw terminals and metal shield installed connected to Pi

Exploded parts diagram.

Assembly