Patent ID: 7224251

Claim:
A magnetic retaining device for attaching a work piece to a machine tool, said magnetic retaining device comprising: a magnetic housing including a first and a second housing members secured together and spaced away from each other, and having different magnetic poles, said magnetic housing including a chamber formed therein, and each of said first and said second housing members of said magnetic housing including a lower portion having a notch formed therein to decrease a bottom surface of said lower portion thereof, at least one bracket for securing said magnetic housing to the machine tool, said at least one bracket being engaged into said notch of said magnetic housing, and a magnetic core rotatably received in said chamber of said magnetic housing, and including a first and a second core members having different magnetic poles, and the magnetic poles of said first and said second core members of said magnetic core being the same as that of said first and said second housing members of said magnetic housing, a magnetic force of said first and said second housing members of said magnetic housing being offset by said first and said second core members of said magnetic core when said first and said second core members of said magnetic core are received in said second and said first housing members of said magnetic housing respectively, and being increased when said first and said second core members of said magnetic core are received in said first and said second housing members of said magnetic housing respectively.