A New Circular Magnetic Chuck
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VOR some time magnetic chucks em
bodying fixed magnets have proved their utility in many classes of engineering work, but, hitherto, they have been of the rdtangular-block type used mainly for holding work on machine beds.
A The latest development, however, is a new rotary type, which is of great value in handling ferrous parts in lathes, grinding machines, etc. It adds to the facility with which parts can he immediately and accurately centred,. and is especially useful in dealing with those in which distortion must be avoided, or on repetition work where speed in setting up is a fn'-tor to be considered.
Permanent Magnets Employed.
In construction, the new Eclipse chuck, manufactured by James Neill and Co. (Sheffield), Ltd., Composite Steel Works, Sheffield, is based upon the same principles as the types already mentioned. Magnetic energy is obtained by providing a system of nickelaluminium-cobalt-alloy permanent magnets of high efficiency, the power from which can be shunted to release the work from the face of the chuck, this operation being effected by the movement of a single lever.
The magnet pack is assembled with alternate rectangular plates of magnet steel and conductor bars of highpermeability steel, separated by brass spacers. When the lever is in the " on " position the energy passes from the magnets through the top plate to the work, the lines of force returning through the inserts in the top plate to the conductor bar and base plate. When the lever is moved to the " off" B34
position the position of the magnets in relation to the inserts in the face plate are altered, and the lines of force are short-circuited, the plate and inserts, in effect, acting as keepers.
To permit the necessary movement, the whole of the magnet pack is ..couplecl to a central spindle provided with a quick thread, which terminates at the two operating points. The flux-control lever cart be inserted at either of two operating points located at opposite sides of the chuck, and the total movement of the lever is only 180 degrees.
The simplicity of the method can
readily be seen by referring to one of our illustrations. The chuck was intended to deal mainly with work requiring finishing cuts, but for such second-operation work on semiTfinished material prolonged tests have shown that it is capable of taking even more than fast finishing cuts, and will withstand shocks which arise in turning objects which are of irregular contour or surface.
The diameter of the Eclipse magnetic chuck is 9 ins., and its width 3 11-32 ins., whilst the indented centre is n ins. in diameter and 3-16 in. deep. The retail price is £18.