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Hand Scraped Guideways

Kashifuji hand scrapes the guideways on all its hobbing machines to create a platform that dampens and absorbs the intermittent cutting forces that are inherent to hobbing process. This feature allows many years of use while still maintaining superb hobbing accuracies.

Generally, machining has limited achievable accuracies due to friction created distortions and/or internal stress relief produced during the machining process. Variations of temperature and humidity during the machine process can also reduce accuracy. Kashifuji utilizes a hand scraped surface finish to assure highly accurate guideways that are not possible by any machining/grinding process.

Hand Scraping is a finish processing method that makes the guideways extremely accurate with an ideal flatness and straightness by manually removing metal in extremely small amount (1~3 micro meters) by the use of a hand tool called a "Scraper". This hand tool has a carbide tipped single edge blade with a blunt angle. This tool is used to relieve the surface tension (create numerous, evenly distributed small, shallow dips or reliefs) in the guideway surfaces. Scraping produces a very flat surface, and the "shallow divots" retain oil which creates smooth sliding surfaces while reducing wear.

Hand scraping is a labor intensive process. The guideway surfaces are painted with a dye then rubbed with a reference straight edge, the dye collects on the highspots. The highspots are then removed by hand scrapping. This process (applying dye, rubbing & scrapping) is continually repeated until approximately 30% of the guideway surface is relieved producing ~70% bearing surface. This process produces an extreme flatness.

Hand scraping is referred to as a "Master's Skill". Kashifuji's skilled craftsmen are able to make accurate micro-meter scraping marks compensating for variations caused by material or temperatures changes. The "scraping pattern" produced, is often referred to as an "art form", and is unique to each craftsman. It takes many years of tedious, difficult work to acquire the experience & skill to become an accomplished Kashifuji "Scraper"