mass

3 Articles

Cheap Lab Balance Needs Upgrades, Gets Gutted Instead

June 12, 2020 by 29 Comments

What is this world coming to when you spend seven bucks on a digital scale and you have to completely rebuild it to get the functionality you need? Is nothing sacred anymore?

Such were the straits [Jana Marie] found herself in with his AliExpress special, a portable digital scale that certainly looks like it’s capable of its basic task. Sadly, though, [Jana] was looking for a few more digits of resolution and a lot more in the way of hackability. And so literally almost every original component was ripped out of the scale, replaced by a custom PCB carrying an STM32 microcontroller and OLED display. The PCB has a complicated shape that allows the original lid to attach to it, as well as the stainless steel pan and load cell. [Jana] developed new firmware that fixes some annoying traits, for example powering down after 30 seconds, and adds new functionality, such as piece-counting by weight. The video below shows some of the new features in action.

Alas, [Jana] reports that even the original load cell must go, as it lacks the accuracy her application requires. So she’ll essentially end up building the scale from scratch, which we respect, of course. At this rate, she might even try to build her own load cell from SMD resistors too.

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Folding Mass Effect Pistol!

May 16, 2017 by 13 Comments

Video game props require a dedicated maker with a repertoire of skills to create. When those props are pulled from the Mass-Effect universe, a little more technological mastery is needed. Bringing those talents to bear,  [Optimistic Geometry] has built a motorized, folding M-3 Predator Pistol!

The gun was modeled in Fusion 360 and 3D printed on an Ultimaker 2 at the  MAKLab Glasgow. [Optimistic Geometry] felt constrained by the laws of our reality, so opted for the smaller firearm thinking it would be an appropriate entry-level challenge. I’m sure you can guess how that went.

There wound up being three main build phases as well as a spring-loaded version to testing purposes. Throughout, [Optimistic Geometry] struggled with getting the parts to latch fully open or closed, as well as working with the small form factor. However, overhauling the motor design — and including some limiters lest it deconstruct itself — a custom latching circuit, and — obviously — a few LEDs for effect, produced a magnificent prop.

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Building An Accurate Equal Arm Balance

August 18, 2013 by 13 Comments

microscale

This interesting take on weights and measures uses a two foot long level as the base for a diy equal arm balance. The balance is the oldest method used for measuring mass. That’s because you don’t even need a reference weight for it to work as long as you are measuring ingredients that are proportional to each other in whole numbers.

The key to accuracy with these scales is to reduce friction at the fulcrum. In this case the fulcrum is made of two upturned razor blades on the base, with a single razor blade resting perpendicular to those on the arm. But because gravity is doing the equalization, the base must be as level as possible. Adjustable feet were added to the base so that it can be leveled on two axes. When the tower at the center was built (using threaded rod) a disc level was used to fine-tune the mounting angle of the two razor blades. The finishing touches include a coupling nut on each end for fine-tuning the balance, and the halves of a tea ball strainer as the weighing vessels.