Smithy GN1300 - Manual (Page 116)

Form-relieved Cutters
• Formed-tooth cutters machine surfaces with curved outlines. You can
sharpen them without changing the tooth outline. Concave cutters mill convex
half-circles; Convex cutters cut concave surfaces.
• Corner-rounding cutters round outside corners. Gear cutters cut gear teeth.
Fluting cutters cut flutes in reamers and milling cutters. Formed-tooth cutters
come in right and left-hand styles various special shapes.
Flycutters
With one or more single-point toolbits or cutters, flycutters perform end milling even
though they're not endmills. They take light face cuts from large surface areas. You must
grind the toolbit properly to get correct rake and clearance angles. Grind toolbits for
flycutters as you grind lathe tools. You can also use flycutters for boring.
Note: When the tool revolves, the cutting tool becomes almost invisible, so be careful.
How To Do Threading
Before beginning to cut threads, it's useful to learn the major terms used in thread
cutting:
• Pitch. Metric pitch is the distance from the center of a thread to the center of
the next thread. To measure pitch in inches, measure an inch on a bolt and count
the threads.
• Pitch Diameter. This is the diameter of an imaginary cylinder superimposed
on a straight screw thread, the surface of which would make an equal width of
the thread and the spaces cut by the cylinder.
• Lead. The lead is the distance a screw thread advances axially (as through a
nut) with one complete revolution.The lead and pitch of a single thread are
identical, but they differ on multiple threads (the lead of a double thread is twice
its pitch; of a triple thread, three times its pitch).
Because screw-thread cutting is generally a part of machine work, anyone interested in
building things of metal should master it. Threading requires a bit of patience and skill.
Before attempting to cut a thread on a workpiece, cut a few practice threads on odd bits
of steel, iron, and aluminum.
Built for thread cutting, the Smithy Granite Series machine, cuts standard internal and
external threads, as well as special threads. You may cut coarse or fine threads in a great
range of threads per inch, in V or square shapes, in established profiles like Unified
National, acme, and metric. You can cut single threads or multiple threads that are
concurrently along the shaft. You determine the type of thread by how you'll use the
screw. Each thread form requires a different shaped tool to cut or chase it.
Granite 1300 Series Operator’s Manual
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