Weighing scales/mass balance

Project Title

Project developed by Nick Veldt

This Open Source Appropriate Technology has been designed but not yet tested — use at your own risk.

This Open Source Appropriate Technology has been prototyped.

Abstract

A simple Roberval measuring scale design that can be adjusted to support different weight multiples. By design, the exact positioning of the masses on the scales does not affect the comparison of weights, unlike a simpler lever-type scale.

Bill of Materials

The parts can be obtained from the following source at Youmagine:

Each part should be printed off once, except for the vbar.stl and platform.stl files, which should be printed twice.

Optionally, glue can be used to fasten the parts more securely together. If the printer prints tight tolerances, sandpaper would not be amiss.

Tools needed for fabrication of the OSAT

1. MOST Delta RepRap or similar RepRap 3-D printer

Skills and Knowledge Necessary to Make the OSAT

Wikipedia article on Roberval balances

Technical Specifications and Assembly Instructions

1. When printing, a large infill is not necessary. As stated before, print two of the platforms and two of the vertical bars, and all other parts once.
2. At 10% infill, printing all parts will take roughly 5 hours, and should use about 143 grams of printing material.
3. Assembly is simple: place the middle piece into the slot in the base, attach the horizontal bars by their middles, link the vertical bars to the end of the horizontal bars, and then top them with the platforms, as shown in the picture.

Cost savings

There are really no commercial counterparts to this design. Most scales available are of a different variety, such as the kitchen scale available at Amazon for $29. The cost of the PLA, at $25/kg, would work out to be approximately $3.82 for this print, saving around $25.

Benefited Internet Communities

• Kijenzi/Hese
• r/chemistry
• r/3DPrinting
• NIH 3D Printing