Bowl 303 by RSO

The Bowl 303
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Round Spinning Objects - ENGINEERING MARVEL

Back in 2019, when I wanted to make a stainless steel yo-yo, on the top of my list was a full-sized stainless steel Bowl. However, as my machinist had yet to attempt a stainless steel yo-yo, I decided put the less risky 50 mm diameter Bowl Mini into production instead. Apart from the TopYo Top Steel, which was a full-sized yo-yo with a 56 mm diameter, stainless steel yo-yos were all in the undersized or micro category at that time. Honourable mentions include the ILoveYoYo Saint Eel (42 mm), Luo Yicheng Kun (27 mm) and YoYoFactory Mighty Flea (25 mm).

Stainless steel is such a complex material to work with primarily due to its high density. Fun fact: the densities of the titanium, stainless steel, and 7068 aluminium RSO typically uses when designing yo-yos are 4.51, 7.65 and 2.81 (in g/cm3), respectively. With such high density, there is drastically less room for maneuverability. As a result, simple design elements like a nipple or inner ring grind would dramatically increase the yo-yo's weight. Removing weight from other areas poses a considerable challenge - no matter how you thin down various parts, the yo-yo is still a hefty unplayable paperweight.

Three years have passed and many companies have embraced the alloy. To my knowledge, there have been 3 full-sized stainless steel yo-yos so far, namely, the YoYoEmpire Thorest, TopYo Top Steel and Hydrangea Lisanthus. Note that they have a general V (Thorest, Top Steel) or W (Lisianthus) shape, as depicted in the images below (pictures from Spingear and YoYoExpert). The designs of these yo-yos are commendable. The Lisianthus deserves a special mention - it manages to squeeze in a nipple, have a W shape and maintain a palatable weight. However, Bowl 303 goes one step further.

You are probably no stranger to the organic shape of the Bowl series. Making an organic shape stainless steel yo-yo is far more complicated than, say, a V-shaped one. The reason is simple: an organic-shaped yo-yo is bigger by volume than a V-shaped one. For the same weight, the walls have to be machined thinner. Bowl 303 weighs only 63.7g and is the lightest amongst the aforementioned full-sized stainless steel offerings. A fortunate thing about the Bowl 303 design is that a protruding nipple or deep groove, which would otherwise have added weight, was not necessary.

Bowl 303 has the thinnest walls of any RSO yo-yo ever made.

In case you’re wondering how the Bowl 303 got its name: the alloy used to machine the yo-yo is 303 stainless steel.

Although the general shape of Bowl 303 is identical to the other yo-yos in Bowl series, the weight distribution is vastly different.

For the Bowl Mini, the stainless steel version is essentially a thinned-down version of its titanium and aluminum versions, with each part of the yo-yo thinned down proportionately. The difference in playfeel between the Bowl Minis was thus solely attributed mainly to the different materials and resultant change in weight distribution.

With the full-sized design of the Bowl 303, limited by the high density of stainless steel, I could not thin down the walls of the yo-yo proportionately from its titanium and 7068 aluminium counterparts. There just wasn’t enough material to play around with. In terms of weight distribution, Bowl 303 has more center weight than its predecessors.

Playfeel-wise, Bowl 303 plays slower, is more laid back and is easier to control than its similar-sized counterparts. Given the difference in both material and weight distribution, it is hard to say which is the dominant factor contributing to the different playfeel. I made the rims more rounded (and consequently slightly thicker) than the stainless steel Bowl Mini, so the yo-yo feels more comfortable in hand.

Bowl 303 is polished to almost a mirror finish - you can see your reflection clearly. The stainless steel looks more premium with a mirror finish than a brushed finish. Although production costs were increased, the finish on Bowl 303 stands above the rest.

Bowl 303 by RSO
Bowl 303 by RSO

The Bowl 303 Specifications:
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Diameter: 56.00 mm / 2.20 inches
Width: 45.00 mm / 1.77 inches
Gap Width: 4.40 mm / 0.17 inches
Weight: 63.7 grams
Bearing Size: Size C (.250 x .500 x .187)
Response: "Slim Pad" Size 19mm OD
Material: 303 Stainless Steel
Designed in: Singapore
Made in: China
Released: December 2022

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