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Hand ScraperA hand scraper is a single edged tool used to scrape metal from a surface. This may be required where a surface needs to be true#Other_uses_of_true, corrected for fit to a mating part, needs to retain oil (usually on a freshly ground surface), or even to give a decorative finish. They are single edged cutting tools. The scraper in the center of the image is a three corner scraper and is typically used to deburr holes or the internal surface of bush type bearings. Bushes are typically made from bronze or a Babbitt_metal. The scaper pictured at the bottom is a curved scraper. It has a slight curve in its profile and is also suitable for bush bearings, typically the longer ones. With precision ground surfaces, any oil film applied to the surface will lack the means to adhere to the surface, especially between two mating parts of exceptional finish. The oil film will be swept away leaving nothing but bare metal and the risk of seizure. Scraping the surface carefully will leave the original high quality surface intact but provide many shallow depressions where the oil film can maintain it's depth and surface tension. Scraping can leave an attractive pattern on the surface and was in fact, the physical evidence of a craftsmen built machine. It is therefore still treated as evidence of craftsmanship by the astute buyer, or the more market savvy machine builders.
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