Magnetic base
A magnetic base is used to attach equipment to ferromagnetic surfaces with the aid of a permanent magnet . Magnetic feet with removal aid have a switchable magnet . When the magnet is switched on, the magnetic field holds the magnetic base in its position; when it is switched off, the magnetic base can be removed from the ferromagnetic surface and moved.
Metal processing and experimental optics
An articulated arm belongs to the magnetic base, see picture on the right. A dial gauge or a deflection mirror , for example, is attached to this. To simplify detachment, the permanent magnet contained is rotatably arranged between two pole pieces .
The internal structure corresponds to a double-sided horseshoe magnet . The gap is filled with a non-magnetic material such as aluminum , plastic or air.
The bottom of the foot is usually hollow (as shown in the graphic) so that it can be attached to cylindrical objects (then with limited holding power). Depending on the design, the magnetic base can also be attached to the side (the back in the picture) to bring the first joint closer to the mounting level.
The associated arm is equipped with lockable joints, for. B. to bring the dial indicator in the desired position to check the centering of a shaft to be manufactured. More modern designs use a locking screw that acts on all joints. Aligning a dial gauge to the measurement object can be done in a more time-saving manner.
Antennas and signaling devices
Such a magnetic base is typically a pot magnet like in a loudspeaker without a detachment aid and is typically used for fastening on the roof of the road vehicle . Depending on the construction, the antenna connection and the grounding can already be integrated. Grounding is typically capacitive via an aluminum foil on the underside, with the vehicle paint as the dielectric and the body panel as the antenna ground.