Acaia’s Rex Tseng weighs up key issues affecting scale accuracy in Knowledge Talks tour

Acaia President and Co-Founder Rex Tseng has completed an East Coast Tour of Australia as the guest speaker of Toby’s Estate’s Knowledge Talks.

From 25 – 28 July, Rex made a whirlwind tour of Sydney, Brisbane, Melbourne and Hobart to impart knowledge on the importance of weight technology.

“It’s been an incredible week,” Rex said. “I could feel the passion from the audiences and the pride baristas have for their work. Most are really happy that we made the Acaia scale for them. Their enthusiasm for the product really drives us forward as a team to make our scales even better.”

Rex’s presentation delved into many key areas about weight technology in today’s society, including how a scale works, the difference between industrial and consumer scales, how to use scales effectively, and common errors.

“A good scale comprises a number of factors. In industrial weighing the three most important components are accuracy, precision and error range,” he said. “However, accuracy doesn’t mean precision. They are two different concepts. Accuracy is how close the measurement is to the target weight, and precision is how consistent your measurements are.”

To ensure such accuracy and precision, Rex explained the importance of error range. “A range of error margin needs to be established before anything can be precise,” he said. “We need to set the target, a range of tolerance. A great scale is one that provides accurate and precise results, every time it is measuring.”

Rex went on to explain that the greatest challenges facing weight scales include calibration, linearity, creeping, temperature, noise, and repeatability, among other things.

“One of the biggest problems I see is calibration. Weighing is about measuring force to gravity. When you move a scale to different locations, gravity will change and if you don’t calibrate, or calibrate enough, the result will be different each time, and it won’t be accurate,” he said.

Rex said even the smallest details such as a café’s air-conditioning could affect the scale reading, as does linearity – one of the biggest problems facing consumer versus industrial scales.

“Scales are not linear. If we put 1000 grams of force on the scales, in reality it may only really by 995 grams,” he said. “There’s no easy solution to solve the linearity problem, but it does come down to three important things: using a better load cell, using Acaia Linear Calibration, and quality control.”

Unlike other industries that use scales to measure the weight of luggage or body mass, Rex says the coffee industry heavily relies on its accuracy each day.

“You may weigh your luggage for a flight once a week, once a month of even once a year. But in coffee, you turn the scale on and use it all the time. Baristas use it to weigh shots, traders use it to measure green beans, and it’s all linked to a dollar figure so it has to be precise,” Rex said.

To use industrial scales such as the Acaia to its maximum potential, Rex says there’s a few easy things users can do:

1. Check the environment. This includes bench tilts, air conditioning, vibration, and magnetic fields.
2. Calibrate. Conduct daily calibration checks and have one calibration weight in place as a reference point.
“Without it you have no idea how to ensure the accuracy of the scale,” Rex said. “You need to control all the variable as much as possible for the best result. It’s like using a watch. If you don’t have a central time, how do you know for sure that you’re on time?”

When Acaia first launched the Acaia Pearl it had a margin of error of +/- 0.2 grams, to which Rex wasn’t satisfied with. Over time, he and his team were able to narrow that margin to just 0.05 grams in the Acaia Lunar product. As such, it’s why Rex says it’s the more expensive of the Acaia scale range.

“When a barista pulls 18.2 grams on the Lunar it is actually 18.2 grams, +/- 0.05 grams,” Rex said. “I was never a coffee professional to begin with, but I do know how to use scales and the impact it can have on coffee. It’s for this reason that I agreed to share my knowledge with Australian coffee professionals. A good barista knows their equipment, such as a coffee machine, and it’s the same with scales. Digital scales aren’t a big mystery but I think if I’m able to share my knowledge about it, it can help baristas and our industry to make more consistent coffee.”

Rex also took the opportunity to share Acaia’s latest invention, the Acaia Brew Bar app, an extraction stand, which connects brew stations and measure beverage output, input, flow rates of pour and drip.

“It’s a great device for new baristas and professionals to use as a training tool to monitor their pour over technique against a master pour on an iPad screen,” Rex said. “Monitoring beverage to coffee ratio is good for consistent serving and if you can monitor your pour and create a recipe that’s more accurate and precise, the coffee outcome will be too.”

In two week’s time Acaia will be inviting baristas to trial this app. For anyone interested email The app hopes to be available for customers to use at the end of August.

This was the third Toby’s Estate Knowledge Talks tour. Toby’s Estates Managing Director Cosimo Libardo says inviting industry icons such as Rex to the country is about bringing education to the Australian coffee scene.

“Knowledge is how things happen, the training is the why. Knowledge is not often shared but we need thought-provoking talks that bring people together, inspire ideas, challenge us, and allows us to learn from game-changers in the industry,” Cosimo said. “We wanted to bring something valuable to the coffee industry, and through speakers such as Mauricio Galindo, Gregory Scace and now Rex, we’re doing that.”

All proceeds from the Knowledge Talks ticket sales will be donated to the Las Nubes Daycare and Afterschool-Learning Centre.

This was Rex’s second visit to Australia, after attending the Melbourne International Coffee Expo (MICE) in March. He says it’ll only be a matter of time before he’s back again.

“I immediately fell in love with the country, its people, and the coffee culture. I’d have to say of all the places I’ve travelled around the world Melbourne is one of the most passionate coffee cities. I’ve never seen anything like it,” Rex said. “I’m so grateful to the team who made the Knowledge Talks event possible, but I really appreciate the people who attended and their enthusiasm. I hope to be back next year – maybe for MICE.”

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