The 12th International Scientific Conference eLearning and Software for Education Bucharest, April 21-22, 2016 10.12753/2066-026X-16-260
E-LEARNING APPLICATION FOR 3D MODELLING OF CUSTOM SHOE LASTS USING TEMPLATES
Bogdan SARGHIE, Aura MIHAI, Ionut HERGHILIGIU “Gheorghe Asachi” Technical University of Iasi, Faculty of Textiles, Leather and Industrial Management, 28, D. Mangeron Street, Iasi, Romania
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Abstract: The shoe last is the key component for manufacturing footwear. Inner footwear dimensions depend on the shape, size and volume of the last. The shape of the last is similar to the shape of the human foot. Last dimensions are correlated with the anthropometrical dimensions of the human foot. The transition between the dimensions of the human feet and the final product dimensions require a high accuracy in the shape's definition. Lasts designed for mass production of footwear comply with certain industrial standards for size and width. The shape and size of the lasts influence the dimensional comfort of footwear. Improperly fitted shoes can lead to physical discomfort for the wearer and has a great effect on its day to day activities. Also during human lifetime, depending on many factors such as work conditions, social status, education, health and so on, feet can suffer different traumas that can lead to modifications of their anatomical structure (hallux valgus, hallux varus, hammer toes, flat foot, fractures and so on). In this case, custom made shoe last are necessary to be made in order to treat or to enhance different feet disorders. Last can be custom made or modified by using manually techniques which require great skill and time or by using dedicated software and computer aided systems. This paper presents the necessary steps to design and create custom made shoe lasts using templates based on individual subject’s feet anthropometric dimensions. This method combines classic solutions with the latest CAD systems, resulting a fast, easy, cheap and reliable way to manufacture custom made shoe last. All the necessary steps are explained in detail and are exemplified by movies. Keywords: health, footwear, shoe last, feet, anthropometry.
I.
INTRODUCTION
While the foot is regarded as the second heart of human transmitting and attenuating the impact forces between the ground and the human skeletal system [1], the shoe last is the hearth of footwear because it is the key component for manufacturing it. A shoe last is a form, made from wood or plastic, that determines the inner dimensions of a shoe model and it represents certain measurements and dimensions of a human foot. Dimensions and characteristics of lasts intended for mass production of footwear were determined in the past by averaging anthropometrical dimensions of general human population and comply with certain industrial standards for length and width. There are different types of lasts, among which the most common ones are those used for trainers, shoes, boots, booties and sandals. Moreover, they can also be classified according to their intended use (women’s, men’s or children’s footwear) or toe shape (pointed, square, round, etc.) [2]. Improperly fitted shoes can lead to physical discomfort for the wearer and has a great effect on its day to day activities. Also during human lifetime, depending on many factors such as work conditions, social status, education, health and so on, feet can suffer different traumas that can lead to modifications of their anatomical structure (hallux valgus, hallux varus, hammer toes, flat foot, fractures and so on). Induced foot deformations from ill-fitting footwear are the major causes for discomfort, pain, and foot problems [1, 3]. In this case, custom made shoe last are necessary to be made in order to design and manufacture good fitted footwear to prevent, treat or enhance different feet disorders.
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Beside the need of custom made shoe lasts for people with different feet disorders, they are demanded more and more by people with healthy feet. Nowadays, the buyers are not seeking only the aesthetic part of shoes, determined by fashion, they are also interested by quality, comfort and dimensional comfort of the shoes. There has been a growing trend among shoe manufacturers to introduce customized shoes to satisfy varying customer style, fit, and comfort needs, thus to increase the product’s added value [4]. This increased demand for custom made footwear is determined by the fact that different people have different feet dimensions (length, width, circumference) and their feet dimensions differ significantly from those of general population. Also people are getting more concerned about their health and they are increasingly aware of the importance of footwear in the prevention of different health problems. Traditionally custom shoe lasts are made manually, but this process is very time consuming and it is made by highly experienced and skilled workers who require years of training. In developed countries and regions, like USA, European Union, United Kingdom and so on, skilled workers for the footwear sector, are getting hard to find, mainly because most of them reach retirement age and young generations look for easier professions. This is why it is necessary to find new methods of training which are more attractive for the younger generations and to pass that knowledge from the footwear industry to them. One way is to deliver learning and training programs using technology in the form of eLearning courses. This is also easier, because in recent years, due to the rapid development of computer technologies, have been developed different advanced techniques of design and manufacturing of footwear products and CAD/CAM techniques [5] so the custom lasts manufacturing is possible [6]. Referring to the 3D modelling of shoe lasts, students have problems understanding and viewing the 3D geometry of complex shapes such as footwear lasts. The current application is intended to simplify this understanding and to enhance their capacity of 3D modelling [7, 8]. II. 3D MODELLING OF CUSTOM SHOE LASTS 3D modelling of custom shoe lasts solutions presented in this paper use computer software Engineer and Last Maker from Delcam Crispin together with InfootUSB Scanning system [7, 9]. The process of 3D modelling shoe last requires the following steps: scanning an individual foot an obtaining its anthropometric dimensions, identifying and choosing an existing last in order to be modified, designing templates based on measured feet anthropometric dimension and 3D modelling the last by applying designed custom templates [6]. 2.1 Obtaining anthropometric dimensions The retrieving of the 3D shape of both foot and last in order to ensure a perfect correlation between them has been made using the InfootUSB system (figure 2), consisting of a 3D scanner and a dedicated computer software [6]. The steps necessary to be made in order to acquire the 3D shape of the foot and to calculate its anthropometric parameters are the following: entering details about the subject (name, year of birth, height, weight, sex, country, ethnicity, sports) and information about the scanning conditions (scan posture, bare or socks) (Figure 1.), placing the foot in the working area of the scanner and performing the scanning process (Figure 2.).
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Figure 1 Details about the scanned subject
Figure 2 Foot 3D scanning
After scanning the foot (Figure 2.), it is possible to have different errors if the scan area is not clean (dirt stains), if the foot is not placed correctly in the scanner working area or if the subject moves during the scanning operation and because of that it is necessary to verify the scanned 3D shape of the foot and to make correction (Figure 3.).
Figure 3 Verifying scanned 3D shape
Figure 4 Placing anatomic points
In order to generate subject anthropometric data sheet (Figure 6.), anatomic points must be placed manually on the scanned 3D shape of the foot (Figure 4). After placing the points, the foot can be visualized in different modes, wireframe, polygon, dots, and surface (Figure 5)
Figure 5 Foot view
Figure 6 Anthropometric data sheet
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2.2
Last selection
After scanning the subject foot and obtaining its anthropometric dimensions, it is necessary to select and identify an existing last, whose dimensional characteristics are similar to those of the subject's foot. The selected last can be one from the existing database of Delcam Shoe Maker or it can be a real last that will be scanned and imported in to the software application. The end result will be the same, a custom made footwear last. In the case of using an existing last, it is necessary to scan the last, using InfootUSB system, going through the same steps as in the case of scanning a human foot, without placing anatomical points and obtaining any dimensions. The scanned last will be exported as an *.stl file type in order to be imported in Delcam Shoe Maker. After importing the scanned last, Last Identification Wizard tool will be used in order to identify the last features (Figure 7.).
Figure 7 Last identification wizard 2.3 Designing templates For creating the templates, based on which the last will be modified, Delcam Engineer software will be used. Longitudinal section of the last and the feather curve contour (insole outline) will be imported in the application from Delcam Last Maker. Using Engineer dedicated tools, for obtaining a new insole outline based on the subject anthropometric dimensions, a construction grid will be created (Figure 8.). After drawing the new insole outline, the template for modifying the bottom surface of the last will be created (Figure 9.)
Figure 8 Construction grid
Figure 9 Insole template
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The same tools will be used and the same steps will be followed to create the templates for modifying the front side (Figure 10.) and the back side of the last (Figure 11).
Figure 10 Front side template
Figure 11 Back side template 2.4 3D modelling of the last The last will be modified using created templates, insole template, front side template and back side template. Using Delcam Last Maker specific tools, the templates will be imported in the application and will be automatically applied to the selected last, which will be modified in order to match the dimensional features of the subject feet (Figure 12).
Figure 12 3D modelling of the last using templates III. CONCLUSIONS Last Maker and Engineer from Delcam Crispin, together with a 3D scanning system like InfootUSB represent a very useful and complete solution for modelling shoe lasts. This combination of tools allows modifying a complex shape like the shoe lasts very easily and with accurate results.
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E-learning lessons presented in this paper help students and professionals from the footwear sector to learn how to model custom shoe lasts using templates based on individual feet anthropometric dimensions. Lessons are presented as a complete package of instruments composed from power point presentations, videos and examples. Acknowledgements This paper was realised with the support of “MOBILITY - Preventia deficientelor de mers si imbunatatirea parametrilor biomecanici la persoanele varstnice prin proiectarea si realizarea incaltamintei personalizate”, project no. 122 / 2014, funded by UEFISCDI in the framework of “PN II - Proiecte colaborative de cercetare aplicativa” program. Reference Text and Citations [1] [2]
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