Jet Tools VBS-3612 - Manual (Page 20)

20
Gage
Use the standard gage (blade thickness) except
when the increased thickness of the workpiece
decreases accuracy and width cannot be
increased to compensate.
Examples of heavy gage applications:
1. When radius cutting in thick materials.
2. When the maximum width usable on the
machine still provides insufficient beam
strength for the blade. (Beam strength is the
blade’s resistance to compression caused
by strong feeding or the type of material
being cut).
Pitch
Pitch is measured in “teeth per inch” (T.P.I.) and
can be constant or variable. Figure 23 shows
blades with different pitches. A fine pitch (more
teeth per inch) will cut slower but smoother. A
coarse pitch (fewer teeth per inch) will cut
rougher but faster.
As a rule of thumb, the thicker the workpiece,
the coarser will be the blade pitch. If you have to
cut a hard or very brittle material, you will
probably want to use a blade with a finer pitch in
order to get clean cuts.
Using a blade with too few teeth may cause
vibration and a rough cut, while too many teeth
may cause the gullets to fill with shavings and
overheat the blade.
As a general rule, use a blade that will have no
fewer than 6 and no more than 12 teeth in the
workpiece at any given time.
The chart on page 23 will aid in determining
pitch for a particular job.
Shape
Figure 24 shows common types of tooth shape.
Tooth shape has an effect on cutting rate.
The Regular blade, sometimes called a “raker”
blade, has evenly spaced teeth that are the
same size as the gullets, and a 0-degree rake
angle. This is a good general-purpose blade,
and often works well with ferrous metals.
The Skip type has fewer teeth and larger gullets,
providing the added chip clearance needed for
cutting softer, nonferrous materials, as well as
non-metallic applications such as wood, plastic,
cork, and composition materials.
The Hook blade has larger teeth and gullets and
a positive rake angle which permits better feed
and chip removal. It is useful for both cast iron
as well as hard, nonferrous alloys.
Figure 23
Figure 24