We do not think it advisable to
try to use a split chuck, although we have seen workmen drive the shell
_A A'''_ out of the collet _D_ and then turn up the pivots _y z_ in said
wire chuck. To our judgment there is but one chuck for turning pivots,
and this is the cement chuck provided with all American lathes. Many
workmen object to a cement chuck, but we think no man should lay claim
to the name of watchmaker until he masters the mystery of the cement
chuck. It is not such a very difficult matter, and the skill once
acquired would not be parted with cheaply. One thing has served to put
the wax or cement chuck into disfavor, and that is the abominable stuff
sold by some material houses for lathe cement. The original cement, made
and patented by James Bottum for his cement chuck, was made up of a
rather complicated mixture; but all the substances really demanded in
such cement are ultramarine blue and a good quality of shellac. These
ingredients are compounded in the proportion of 8 parts of shellac and 1
part of ultramarine--all by weight.
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