Computer-Controlled Machining#

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Since FabLab Kamakura does not have a large CNC, we used ShopBot with the help of a wood store Enokido-lumber in Shin-Kiba.

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Type of Shopbot we used was PRS-Alpha. It was deeper in height than the normal one and had an air pump to support the mill.

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When using the ShopBot, the default procedure is to turn on the power, attach the collet and mill, and set the XY and Z axis origins. The Z-axis is set by placing a metal plate on the surface of the machine, attaching a special clip to the metal part, and then energizing it.

Make Test Piece#

In order to find the right offset value, a test piece was machined with different widths of 0.2mm each. In this time, we use 18mm-thick lumber plywood. We found that an offset value of +0.2 to 0.4 mm for height and +0.4 mm for width in total was just right.

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Testing Runout#

Runout is defined as the rotation inaccuracy which occurs when the tool is no longer aligned with the main axis. *. Ideal a tool with 1/4 inch should leave a trace of exactly 1/4 inch.

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The measured runout is between 6.30 and 6.40mm, 1/4inch is 6.35mm.