Aerostatic device damper

An aerostatic device for ultra precision machine tools, the aerostatic device having a damping device for use at any angle, including vertical, and comprising:

• a male part (14;114) having a projecting portion (16;
• 116);
• a female part (10;
• 110) having a channel (12;
• 112) in which the projecting portion (16;
• 116) of the male part (14;114) is slidably receivable;
• means (22;
• 122) for providing a magnetic field, the magnetic field means (22;
• 122) being at or adjacent to the projecting portion (16;
• 116) of the male part (14;114) and/or the channel (12;
• 112) of the female part (10;
• 110);
• and
• magnetic oil (26;
• 126) interposed between the projecting portion (16;
• 116) of the male part (14;114) and the channel (12;
• 112) of the female part (10;
• 110) and only within the magnetic field of the magnetic field means (22;
• 122), the in use magnetic oil (26;
• 126) being retained in or substantially in position by the magnetic field, so that undesirable movement of the male part (14;114) and/or female part (10;
• 110) is damped by the oil (26;
• 126) without the oil (26;
• 126) being displaced from the projecting portion (16;
• 116) and/or the channel (12;
• 112).