We have investigated the OGA (giant frame saw used for ripping) painted in the ROKUDOE， a picture painted a hell， which was found in the Gokurakuji temple in Hyogo Prefecture by Hyogo Prefectural Museum of History at 1984. It is said that OGA was transmitted to Japan from China in early 15th centry. However， the ROKUDOE investigated was painted in early 14th centey. In Japan is there any possibility that OGA had existed in early 14th centry? (1) In the pictures painted a hell， a saw was used for fiends torture the damned not for building a structure. And in many case， the forms of these saws corresponded to a form used for original works in the time that the picture was painted. (2) In other pictures， a saw was used for cutting only the damned， but in the ROKUDOE， the scene that the OGA had been ripping timber with the damned was painted. (3) The ROKUDOE shows us the OGA's form exactly， and the way of it's sawing realistically. (4) The ROKUDOE is an important datum to give a possibility that OGA had been transmitted to Japan in early 14th centry. (5) In another picture of a hell that was painted in near time to the ROKUDOE， we can find another OGA that seemed to be used for cross-cutting. But there was a case that a picture of a hell in Japan was copied from the model in China. Concerning this point， we'll have to carry out the investigation in the future.

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According to a study conducted by the Institute for the Science of Labour in 1943， Japanese master carpenters had “a complete set of 179 tools”. And 8 hammers and 1 mallet were included in it. Then， what kind of hammers and mallets did they use in the 17th–19th century? According to this research， the outline of hammers and mallets in Japan of the 17th–19th century is the following (1) At least Japanese carpenters used 3 types of hitting tools，“Kana–tsuchi” (hammer)， “Sai– tsuchi or Ki–zuchi” (mallet) and “Ahi–no–tsuchi” (pounding commander). In their tool box of the 17th–18th century we can't find “Gennou” (hammer) those they used in the late 19th–20th century. (2) Japanese carpenters used mallets for hitting chisels， hammers for hitting nails and pounding commanders for jointing beams. But they didn't use hammers for hitting chisels till the mid 18th century. (3) In the shape of hammers used by Japanese carpenters， there were 3 types at least. The first type was the hammers that both faces of its head were a square and different in size. The second type was the hammers that both faces were different in size and large face was a circle. And the third type was the hammers that both faces were a circle and the same size. (4) In the shape of mallets used by them， there were 2 types at least. The first type was the mallets that both faces of its head were a circle and the same size. The second type was the mallets that both faces were an octagon and the same size. (5) In the shape of pounding commanders used by them， there were 3 types at least. The first type was pounding commanders that both faces of its head were a circle and the same size. The second type was pounding commanders that both faces were a rectangle like an oval. And the third type was pounding commanders that both faces were an octagon and the same size (6) Perhaps in the late 18th –early 19th century， Japanese carpenters began to use hammers for hitting chisels. It seems probable that the main factor of its change was the labor efficiency in the constructions.

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The authors prepared again four pieces of experimental saw of the “KONOHAGATA”，and carried out a groping test for the purpose of pointing out a right angle of the Fleam (the side angle of a tooth that is usually called a NAGESHI in our country). 1) All the saws had filed teeth only on the middle part of the blade between about 150 mm long， in expectation of an adjustment to the experiment. 2) The profile of the saw teeth is just like an equilateral triangle， and was given a vertical angle of about 55 degrees. 3) Each of the saws was set with a different Fleam angle， from 30 to 45 step 5 degrees. 4) As a result of this experiment， a suitable Fleam angle for this type of saw seems to be in the neighbourhood of 35 to 40 degrees.

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One of the condition for the good carpenter blade tool is to be able to sharpen the blade edges and to maintain the sharp edge for a long time. High carbon steel or alloy steel　as a blade material is used for this purpose. Carpenter blade tool are composed by　forgewelded thin steel to wrought iron or mild steel in Japan. It is necessary to make the irreguler carbide occured by the overheat of forgeweld the fine globular carbide. However， most of blacksmith accumulate their experience by try and error to get the good metal structure. It is unknown， usually how to achieve the process of the fine globular for good tool. So I showed in this report plane blade steel microstructure of heat treatment process in cooperation with plane blacksmith studying earnestly. 「AOGAMI」， a kind of alloy steel added tungsten， was used as a blade material. It was found in the plane blade of this research that the the fine globular carbide was already formed in the process of repeat forging ahead of annealing， though method to get the the fine globular carbide is annealing in general. It was uderstood that 「HIZUKURI」 said by blacksmith， forging in heat， was significant

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