According to a study conducted by the Institute for the Science of Labor in 1943，a professional carpenter uses 179 different tools on average. Among them are types of planes belonging to 18 separate categories. This constitutes the standard set of planes used in modern carpentry. What types of planes were used from the 17th to 19th centuries? (1) From the 17th to 19th centrise， at least 26 types of planes belonging to 12 categories were used. They can be roughly classified as those for planing， groove cutting， curved surface cutting， chamfering， and plane body adjusting. (2) The standard plane for flat-surface planing had a single plane blade fixed to the plane body in the blade groove. (3) Its length varied from “7 sun” (210mm)to “9 sun#8221; (270mm). (4) There were three processes : rough cutting， processing and finishing. The mouth of a finishing plane was as amall as the diameter of a hair. (5) According to documents and pictures handed down from the past， carpenters cut wood with the pulling stroke as early the 17th century. (6) The documents and pictures also suggest that it was in the beginning of the 19th century that carpenters started to use a bench and adopt a standing stance when working (7) It seems that upgrading the precision of the cutting mechanism of a plane took place from the latter half of the 17th century to the beginning of the 18th century. (8) According to documents and pictures， we can infer that both spear head planes and normal planes had been used until the late 17th century and that the plane became the mainstream tool for finishing in the 18th century.

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Recently， the author conducted site surveys of plane body manufactuers in Tokyo， Osaka and Sanjo in Niigata prefecture. In the past， plane bodies were all made by carpenters themselves. As times have changed， however， professional plane body manufactures called “daiya” have appeared and their products are now readily available. One of the raw materials needed for a plane body is “shirakashi，” which is cut in autumn， winter and spring， and dried before processing. Materials split with an axe， as used in the meiji era， gradually gave way to mass —produced sawn ones in the Showa era. Some time before，“ daiya ” used to procure a bulky timber material from woodworking plants and cut it into blocks to make individual plane bodies. At present， completed blocks for unit plane bodies are circulating for immediate use. The processing method has also changed. In the past， users bedded the plane blade into a half —finished Plane body， then perfomed final finishing. This process is known as “half finished plane body bedding. ” Now， however， the plane blade is bedded in a completely finished plane body， a process known as “finished -plane body bedding. ” Craftsmen who are skilled in the traditional manual processing of plane bodies have gradually decreased in number. As a result， the mainstream method today is mechanized processing. However， manual work is still indispensable to the finishing of plane bodies.

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To clarify the effects of bed angle， seven categories of timber were finished with smoothing planes having sharpened blades bedded at bed angles of 31 to 44 degrees. The surface roughness of these specimens was measured with a surface roughness tester for comparison. Except for lauan， which showed different characteristics， all other categories of timber had smaller values for the average maximum peak –to –valley height (Rmax) of the roughness smaller bed angles and larger blade tip angles. As for the relation ship between the maximum roughness (Rmax) and the bed angle， larger bed angles resulted in larger values of roughness and variance. When the bed angle becomes smaller， the variance again becomes larger. Thus， the smallest variance was measured when the tangent of the bed angle was 0.8.

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