Router bit and method of grinding said bit

Claim 1

The method of grinding a router bit for the cutting of wood, plastic and soft metals, said router bit formed with a shank portion and at least one straight flute, the flute having as insert of hardened material which in its secured position is formed to provide a short flat outer cutting edge face and adjacent this edge and in the face of the insert is formed an arcuate concave relief, the grinding of the router bit including the steps of: (a) mounting the router bit in a relief grinding fixture and positioning the axis of the shank so that the axis is displaced from the center of the grinding radius after which there is the step of grinding the outer flute to provide the desired flute relief; (b) repeating the relief grinding of and for each flute and after all flutes have been relief ground there is performed the step of removing the router bit from the relief grinding fixture; (c) mounting the router bit in a rotatable holder with the axis of the router bit and holder in coincidence and rotating the holder to bring the short flat face of the flute to be sharpened and the axis of the bit into a set plane which is parallel to the cutting face of that grinding wheel which is to finish the flat face, this position being the stop position; (d) clamping the router bit in this stop position and moving the router bit and holder a determined distance transversely to the set plane, this distance being an amount sufficient to establish a selected cutting angle of the cutting edge, which angle is between 15* and 35*, and (e) moving the grinding wheel into grinding engagement of only the short flat face of the flute and to lightly grind this face with longitudinal passes of the grinding wheel and after a sharp edge has been produced to discontinue the grinding of the flute face, this sharpening step being repeated for each flute until all flutes are sharpened after which the router bit is removed from the rotatable holder.

Claim 2

The method of grinding a router bit for the cutting of wood, plastic and soft metals, said router bit formed with a shank portion and at least one straight flute, the flute having as insert of hardened material which in its secured position is formed to provide a short flat outer cutting edge face and adjacent this edge and in the face of the insert is formed an arcuate concave relief, the grinding of the router bit including the steps of: (a) mounting the router bit in a relief grinding fixture and positioning the axis of the shank so that the axis is displaced from the center of the grinding radius after which there is the step of grinding the outer flute to provide the desired flute relief; (b) repeating the relief grinding of and for each flute and after all flutes have been relief ground there is performed the step of removing the router bit from the relief grinding fixture; (c) mounting the router bit in a rotatable holder with the axis of the router bit and holder in coincidence and rotating the holder to bring the short flat face of the flute to be sharpened and the axis of the bit into a set plane which is parallel to the cutting face of that grinding wheel which is to finish the flat face, this position being the stop position; (d) clamping the router bit in this stop position and moving the router bit and holder a determined distance transversely to the set plane, this distance being an amount sufficient to establish a selected cutting angle of the cutting edge, which angle is between 15* and 35*, and (e) moving the grinding wheel into grinding engagement of only the short flat face of the flute and to lightly grind this face with longitudinal passes of the grinding wheel and after a sharp edge has been produced to discontinue the grinding of the flute face, this sharpening step being repeated for each flute until all flutes are sharpened after which the router bit is removed from the rotatable holder.