The orientation of a machine 2 relative to a work-piece 10 is manually controlled by means of an alignment device 4. The device 4 includes a light source 24 rigidly attached to a foot 12 that is resiliently movably attached to the main body 18 of the device. The body 18 of the device 4 houses a light detector 26 for detecting a light beam from the light source 24, the position of the region on the detector 26 illuminated by the beam depending on the orientation of the machine 2 relative to the work-piece 10. The operator is provided with feedback on whether the machine 2 is correctly aligned with a target orientation (usually perpendicular to the surface) and concerning the direction of corrective movement required, if any.