Dome knob for Hex bit shank 1/4 in (6.35 mm AF) - 4 sizes 20/25/30/36 mm, no supports

A dome over a knurled band. The dome is deliberately flatter than a hemisphere: a true half-sphere would print at 65 degrees of overhang and need supports. Fits a standard 1/4 inch hex bit shank (ISO 1173, 6.35 mm across flats) and turns the knob into a thumb driver for fine screws. The bore is built to 6.45 mm; printed holes come out a tenth or two tight, so the bit sits snug without a hammer. ## Sizes in the download All 4 diameters, same shaft fitting: | Diameter | Height | Volume | Weight i…

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