Page 165 - My FlipBook

CYLINDER OR BLOCK FILLING. 161

sharp ; ordinarily it should not taper, or at least very

slightly. For forming the conical blocks, some prefer
the tapered broaches, but they can be as well made

on the parallel-sided instruments. The strip being
taken between the thumb and the index ringer, is
rolled on the broach equally, till the block or cylinder
is large enough, when the strip is broken off. The
sizes of the principal part of the blocks should cor-
respond with the sizes of the cavities to be filled.
Different sizes and forms will be required in almost

all cases. Relatively large cylinders may be em-
ployed for the principal part of the filling. If the
walls of the cavity are parallel, almost all the blocks
may be truly cylindrical; but if there is an under-
dipping of one or more of the walls, the blocks
adjusted to that particular part should be cone-shaped,
corresponding to that under-dipping. A number of

small graduated cone-shaped blocks, of different de-
grees of density, will be required for completing each
filling; as the aperture becomes smaller, smaller
blocks will be needed. The cone-shaped blocks are
formed, by gradually running the strip back from the
point of the instrument as it is wound on ; greater or
smaller taper can be given to it, as the strip is run
less or more rapidly back from the point. The
density of the block can be regulated by the firmness
with which the strip is held between the thumb and