Abstract: A grinding machine has two grindstones, each of which has a grindstone shield disposed thereover. The grindstone shield is provided with a dust receiving portion in communication with a vacuum cleaner via a connecting tube. Pivoted to the grindstone shield is a worktable having an angle adjusting plate with a bevel scale disposed along the outer edge thereof. A plurality of concave retaining surfaces are constructed along the outer edge of the angle adjusting plate in such a manner that the concave retaining surfaces are corresponding in locations to a plurality of predetermined angles. The grindstone shield is further provided with a locating element engageable with the concave retaining surfaces of the worktable for facilitating the angle adjustment of the worktable. The dust produced in the grinding process is removed from the machine by the vacuum cleaner so as to prevent the dust from polluting the air at the work site.