Each
comes with a carbide insert, hold-down screw and special Torx key. The
3/8" round shank is held in a P/N 7600 tool post. The 2260 holder
accepts a 55° insert and requires a minimum hole size of 3/4". The 2259
holder accepts an 80° holder and fits into a minimum hole size of 1/2".
In
addition to fitting into a smaller hole, the 80° insert offers a little
more strength, while the 55° insert will cut into a sharper corner.
The
holders are made from case hardened steel with a black oxide finish. A
flat is ground on one side so the two hold-down screws of the 7600 tool
post can tighten against it to keep the tool from rotating.
Overall length of the holder is 3-1/4", and with both hold-down screws
engaged it can be extended to bore a hole a little over 2" deep. Because
the further the tool is extended from the tool post, the greater the
tool flex, the tool should be extended no more than is necessary to bore
the hole you need. Longer boring tools are offered by other
manufacturers, but due to tool flex, Sherline does not recommend
extending them more than about 2" from the tool post, so their extra
length is of little value. Tool flex in a boring operation can result in
a poor finish, boring a tapered hole or, in the worst case, an insert
to bite in and break.