Special Jury AwardOJIGI TOKURI Self-Tilting Sake Bottle
Shoko Kawata, Kazuki Takenouchi

Shoko KAWATA, Kazuki TAKENOUCHI “OJIGI TOKURI (Self-Tilting Sake Bottle)” 2017, Material: VeroWhite, Size: 94W x 94D x 86H (mm)OJIGI TOKURI can tell the remaining quantity of sake inside by changing its tilting position, while remaining sake is invisible in a
traditional one made of opaque china. This unique behavior of the tilting is generated by its computationally optimized asymmetricalinner configuration, which changes the center of gravity with a decrease of sake with holding a stable tilting position in 4 steps.
Moderate movement to the next stable position is given by double curved surface patches. Elegant openwork and deep extrude cut
figured with cherry blossoms implicitly show the mechanism of tilting.

18

Special Jury Award

Keywords: Digital modeling, Digital fabrication, Statics, Tokuri, Optimization, Engineering calculation

1 Introduction

The authors’ work OJIGI TOKURI at the top of this page

In a Japanese traditional style of drinking sake for two, sakehelps drinkers and servers see the quantity of sake in the bot-is served in a tokuri, one of Japanese traditional bottles fortle without impolite behaviors by tilting depending on the re-sake holding standard content volume of 180ml or 360ml

maining. The name OJIGI TOKURI comes from a Japanesecalled as 1-gou toukri or 2-gou tokuri, respectively. As a

traditional greeting, ojigi, making a bow; tilting behavior ofmanner in this case, drinkers are expected to fill sake eachtokuri is similar to ojigi in terms of both moving and having

other into partner’s small sake cup, sakazuki, and at every

some of degrees as illustrated in the top right figure.

filling sake in the tokuri gradually reduces. As such tokuri isin general an opaque china, the remaining quantity is esti-

2 Idea and design requirements

mated by shaking the tokuri or by looking into it, and theSince tilt of OJIGI TOKURI is caused by a move of theempty tokuri is often laid down as a sign of drinking up. All

center of gravity with a decrease of sake in tokuri, its

these behaviors are however against good manners.

asymmetrical inner surface configuration not interfering with19

Special Jury Award

the flow of sake should be carefully determined to satisfy theinclination for each particular quantity of sakestatics in accordance with the outer contour. In addition to· tilting with moderate motion not to pour out thesake in tokuri nor break itself by impact

the above requirements, the authors imposed following
design requirements to the tokuri for a practical use:

In order to simultaneously meet these complex requirements,· holding the standard content volume (180ml)

a numerical evaluation is necessary on geometry and statics· visualizing a quantity of remaining sake with somefor a tentatively determined configuration at every tilting

tilting degrees and staying stable at rest in a single

position followed by a modification to a better result.

20Special Jury Award

3 Modeling environment and procedure

4 Final model of OJIGI TOKURIAs design of such a novel product is a creative work,

The final model is shown at the top of the first page and insuccessive modification and even introduction of addtional

Fig.2(b). The behavior has been improved through the fiverequirements and constraints found out in the process will be

prototypes fabricated with FDM 3D printer as shown in Fig.3

required. To handle such process, the configuration of tokuri,from the left to the right.

cross-section of outer and inner surfaces, was evaluated and

The five prototypes are constructed with an axially

optimized by use of spreadsheet, not special CAE tools nor asymmetrical outer surface or combination of ruled surface;programing languages that require special knowledge andthe final model is constructed with small curved surface

skills to users. Furthermore, as shown in Fig.1(a), the users

patches. The patches are generated by connecting regularcan confirm calculated results by instantly illustrated outline

octagons by use of loft surface, one of the most fundamentalof the tokuri and the position of center of gravity at eachfunctions of 3D CAD, octagons which are storied along

tilting position as 2D plots.

tokuri’s centerline with a relative revolution between theDigital 3D modeling of the tokuri was carries out on Fusionneighboring two polygons. Such curved surface patches

360: 2D sketch was drawn by tracing the profiles determinedseem to be effective to give OJIGI TOKURI a moderate

based on calculation on spreadsheet, and 3D surfaces intilting motion to a feasible direction, being expected to avoid

Fig.1(b) were generated based on the sketch. Its outer andtokuri rolling off the table and being damaged by the impact.

inner surfaces were then joined into a solid body in Fig.1(c).

To control its tilting behavior, an appropriate fillet size isFinally, openwork and lightening in Fig.1(d) were added forchosen for each edge of patches.

better performance of tokuri.

The contour of the bottom face is a circle for a smooth start

The openwork is partly for a better performance by makingof tilting. Surface cut with a truncated circular cone isfine adjustment, and also for disclosing the existence of inner

applied for the connection between the circular bottom facepartition, impressing the mechanism of generating its

and the octagonal section.

interesting behavior. In the modeling of the openwork,

Also to implicitly show the existence of solid weight

Boolean operation was applied with a basic solid pattern

opposite to the hollow partition, the other mechanism of theshown in Fig.2(a) and arranged on the shell of hollowed area

tilting behavior, rather deep extrude cuts having a contour ofin Fig.2(b).

flower are added.

21