A grinding machine (30) has a rotatable grindstone (31) and a support structure (32). A jig device (10) is provided for bringing a knife blade (20) to be sharpened into controlled engagement with the grindstone (31). A jig arm (11) of the jig device (10) is provided with attachment means (13) for attachment to the support structure (32) in a proper position for the grinding of the knife blade (20). The jig device (10) also comprises a resilient clamp (12) for receiving and fixing the knife blade (20) in the clamp (12), in operation.
