Instruction Manual Glossary of Terms
Lead Angle: The angle of the helix of a screw thread or worm thread. It is the
measure of the inclination of a screw thread from a plane perpendicular to the
axis of the screw.
Lead of Thread: On a single threaded screw, the distance the screw or nut advances
in one complete revolution.
Left Hand Cutter: In lathe work, a cutting tool that cuts when fed from left to
right or toward the tailstock. For milling cutters, when viewed from the spindle
or shank end, the cutter would turn counterclockwise.
Left Hand Screw: One that screws into the mating part or advances when turned
to the left or counterclockwise.
Lever: A simple machine for obtaining mechanical advantage. The lever consists
of a rigid arm or bar pivoted or bearing on a point called the fulcrum and has a
weight arm and a power arm.
Loading: Filling of the pores of the grinding wheel surface with the material being
ground, usually resulting in a decrease in production and poor finish
Lock Nut: A type of nut that is prevented from loosening under vibration. The
locking action is accomplished by squeezing, gripping, or jamming against the bolt
threads.
Machine Tool: The name given to that class of machines which, taken as a group.
can reproduce themselves.
Mandrel: A hardened, tapered, or slightly tapered metal shaft, with the outside
precisely concentric with the center holes, which is pressed into an accurate hole
of a workpiece to support and revolve the part between centers.
Metal Slitting Saw: A thin milling cutter for slotting or cutting off stock in a mill
ing machine.
Micro Inch: One millionth of an inch.
Micrometer: A precision, screw adjusted measuring instrument with which dimen
sions can be read in thousandths and ten-thousandths of an inch.
Micrometer Index Collar: A dial on the screw of a machine tool to indicate the
movement of the "screw or parts attached to the screw and usually graduated to
read in thousandths of an inch.
Mill: To remove metal with a rotating cutter on a milling machine
Millimeter: One thousandths of a meter. Equivalent to .03937 inches, One inch
contains 254 millimeters.
Morse Taper: A standard taper of approximately
⅝
inch per foot. Used on lathe
centers, drill shanks, etc.
Mounted Points and Wheels: Small bonded abrasive shapes and wheels that are
mounted on steel spindles.
Mounting: Putting a grinding wheel on the arbor or spindle of the machine.
Nut: A metal fastener of square, hexagon, or other shape, having an internal thread
which screws onto a bolt, stud, or arbor.
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