Keywords

1 Introduction

“Kana-ami” is a kind of metal wire network in Japan as shown in Fig. 1. It’s employed as one kitchen instrument (Bread grill) or fence knitting for cultural relic, which was once prevailed many years ago in the old Japan and has been decreased in the development of social industrialization. Additionally, traditional handcrafts are handed down mainly through oral teaching and extempore creation, making proceed of teacher-student relations, family relations and art education.

Fig. 1.
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The Japanese traditional handicraft of “Kana-ami”

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However, it is very difficult for learner to copy the weaving motion from master. Usually, the master only can pass the every essential to the prentice but the rest were on your own. Therefore, the technique of tradition handcrafts is reliant on apperceiving heavily as “Kana-ami”. Without apperception, it cannot be learnt no matter how hard you study, which was considered as the special tacit knowledge. And quantified the correct apperception of master is the main target in this study.

In previous research, the expert’s motion of the “Kana-ami” weaving process was clarified, which was “brief, frequent, fast” during the twisted cross [1–3]. As the same time, the different “Kana-ami” hexagonal structure in vertical direction between expert and non-expert also was explained in the free fall experiment by high-speed camera [4, 5]. The metal wire net of “Kana-ami” made by expert presented the convex shape in vertical direction so that helps buffer the fall. The results confirmed the superiority of the product made by expert.

Therefore, the accurate identification and effective expression of the hexagonal structure of “Kana-ami” were focused in this study. The Industrial CT (X-Ray) system was applied, through scanning the whole metal wire network products made by expert and non-expert, The “Kana-ami” structure was orientated and recorded base on X-Ray there-dimensional scanning.

The velocity, acceleration, and jerk were also calculated as the same time, in order to further analysis the feature of motion between expert and non-expert. As well know, the hardest part about movement for a learner is the motion changing moment, which the velocity and direction of movement generated uncertain changing. However, the structure difference caused by different weaving motion was very difficult to explore, which was directly affect the “Kana-ami” product performance.

In additionally, the precise three-dimensional structure was observed and analyzed. The characteristics of hexagonal structure for expert and non-expert were compared. It was confirmed previous conclusion that the expert’s structure was presented a curve shape and reasonable orientation. It is means that expert’ motion was able to weaving a curve hexagon of “Kana-ami” mental wire network.

The purpose of this paper was through three-dimensional orientation scanning by X-Ray to clarify the “Kana-ami” structure features between expert and non-expert’s motion in order to demonstrate expert’s motion can generate excellent “Kana-ami” product, which was considered as a current movement technique of “Kana-ami” weaving method.

2 Experiment

2.1 Participants and Weaving Procedure

In this study, the two masters with 46 years and 10 years wire netting technique experience were employed as participants, which called expert and non-expert. The expert and non-expert not only have parent child relationships but also have mentoring relationship. And both of them would be committed to heritage this Japanese handicraft technique of “Kana-ami”.

The subjects were required to make a “Kana-ami” product. Figure 1 shows a photo of one of completed samples. As same with previous research, two twisted crossed were called “Twisted cross” during the whole weaving process. “First twisted cross”, “Second twisted cross”, “Right-line”, “Left-line” and each inside vertexes were used to call the hexagon elements as shown in Fig. 2.

Fig. 2.
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The industrial CT system of “Toscaner”

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2.2 Experimental Process

The three-dimensional orientation structure of “Kana-ami” was measured by industrial CT. (High resolution miniature CT TOSCANER - 32300 mu FD/32300 mu hd; Toshiba Co. Ltd.), which X-ray tube voltage generator was 230 kv, and the focus size was 4 microns (without wire). The spatial resolution was 5 microns.

The expert and non-expert’s “Kana-ami” products were scanned by industrial CT system through X-Ray as shown in Fig. 3. The three-dimensional data of expert and non-expert’s “Kana-ami” products were analyzed by the software of “Solidworks”.

Fig. 3.
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The industrial CT system of “Toscaner”

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3 Result and Discussion

3.1 Interval-Timing Analysis

The image results of three-dimensional scanning were shown in Figs. 4 and 5 (Expert and Non-expert). The whole final “Kana-ami” products of expert and non-expert were presented by X-Ray technology. Threshold value was adjusted into the most clear level.

Fig. 4.
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The perspective drawing of expert’s “Kana-ami”

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Fig. 5.
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The perspective drawing of non-expert’s “Kana-ami”

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3.2 Interval-Timing Analysis

The numerical models of the whole product made by expert and non-expert were illustrated in Figs. 6 and 7 respectively. The hexagons features of expert and non-expert created by three-dimensional scanning were demonstrated as the same with previous research, which was proceeded by digital image processing technology.

Fig. 6.
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The simulated diagram of expert’s “Kana-ami”

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Fig. 7.
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The simulated diagram of non-expert’s “Kana-ami”

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In the overall view, as shown in Figs. 6 and 7, both vertex 1 and 4’s average angle value of 5 knitted samples by expert showed nearly 100°, which were approached 95° at the same location of non-expert. Expert and non-expert’s angle values of vertex 2 and 5 were almost higher than vertex 3 and 6. The expert s vertex angle of 1 and 4 were bigger than non-expert. On the contrary, compared with non-expert, expert’s vertex 2 and 6 were smaller then non-expert. 3rd hexagon on 3rd line at the same location made by expert and non-expert were focused on Fig. 8(a) and (b).

Fig. 8.
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The 3rd hexagon on 3rd line in frontal side

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The bulge direction of ‘Right-line’ at the same location made by expert and non-expert were focused in frontal side as shown in Fig. 8(a) and (b).

Compared with non-expert, the bulge direction of ‘Right-line’ by expert was upper ward as red arrow in Fig. 8(a), which was considered that higher than non-expert more than 0.05 mm in previous research. The bulge direction of the ‘Right-line’ by non-expert was down ward as red arrow in Fig. 8(b).

The bulge direction of ‘Right-line’ at the same location made by expert and non-expert also were focused in axial side as shown in Figs. 9(a) and 10(a). And the expert and non-expert’s outline of schematic diagram located at the hexagon were shown in Figs. 9(b) and 10(b).

Fig. 9.
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The expert’s 3rd hexagon on 3rd line in axial side

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Fig. 10.
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The non-expert’s 3rd hexagon on 3rd line in axial side

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As same with above result, the bulge direction of ‘Right-line’ by expert was upper ward as red arrow in Fig. 9. The bulge direction of ‘Right-line’ by non-expert was left upper ward as red arrow in Fig. 10. It was confirmed the result of previous research that different making motion technique was deemed to the main reason for the differences in structure of final products between expert and non-expert, which was directly affected the hexagonal shape, which was deemed that expert’s shape of “Right-line” was made under suitable rotation angle.

According to this result, the curve shape of “Right-line” was similar between expert and non-expert. However, the bulge direction was different. The expert bulge direction was upper ward, which was showed more significant radian and more convex to the frontal side. The non-expert bulge direction was convex to left upper side.

The peak of curve shape for “Right-line” and “Left-line” was illustrate on Fig. 11, which the expert and non-expert were shown in Fig. 11(a) and (b) respectively. As shown in Fig. 11, the peak of the ‘Right-line’ made by expert was located in the central as shown in yellow color. However, the peak of the ‘Right-line’ made by non-expert was located in the down side as shown in yellow color, which was closed with next “First twisted cross”. And the length of the “Right-line” made by expert was shorter than non-expert’s. It was second main reason that the expert’s “Right-line” was more convex to frontal side than “Non-expert”.

Fig. 11.
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The curve shape of “Right-line” for expert and non-expert in inclined side

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4 Conclusions

As a conclusion, the three-dimensional structure of expert and non-expert’s “Kana-ami” product was accurate scanning. The result of “Right-line” shape was shown the similar curve between expert and non-expert. However, the bulge direction was different. The expert bulge direction was upper ward, and showed more significant radian and more convex to the frontal side. The non-expert bulge direction was convex to left upper side. It was confirmed the previous suppose that the different “Kana-ami” making motion will influence on the final product.