Fig. 1531.
Suppose a very thin piece of work is to be planed, and in order to plane it parallel, which is ordinarily a difficult matter, it must bed fair down upon the face of the vice, which it is caused to do when chucked as in [Fig. 1531], in which the work is shown laid flat upon the face of the vice, and gripped at its edges by the pieces a, a.
These pieces, it may be noted, do not bed fair against the gripping faces of the jaws, but are a trifle open at the bottom as at e, e, hence when they are pressed against the work they cant over slightly and press the work down upon the chuck face causing it to bed fair. Furthermore, the work is supported beneath its whole surface, and has, therefore, less tendency to spring or bend from the holding pressure; and as a result of these two elements much thinner work can be planed true and parallel than is possible when the work is lifted up and supported upon separate parallel pieces, because in the latter case the work, being unsupported between the parallel pieces, has more liberty to bend from the pressure due to the tool cut, as well as from the holding pressure.
Fig. 1532.
[Fig. 1532] shows the chuck holding a bracket, having a projection or eye. The work rests on pieces b, b, and is gripped by pieces a, a. It will be observed that a, a being beveled enables the cut to be carried clear across the work.
