27
Blade Selection
Using the proper blade for the job will increase
the operating efficiency of your band saw, help
reduce necessary saw maintenance, and
im prove your pr oduc tivity. Thus, it is important to
follow certain guidelines when selecting a saw
blade.
Here are factors to consider when selecting a
blade:
• The type of material you wi ll be cutti ng.
• The thickness of the workpiece.
• The features of the workpiece, such as
bends or c urves wit h small r adii.
These factors are important because they
involve basic concepts of saw blade design.
There are five (5) blade features that are
normally changed to meet certain kinds of
sawing requirements. They ar e:
1. width
2. pitch (number of teeth per inch)
3. tooth f orm (or shape)
4. the “set” of the t eeth
5. the blade material itself
Width
Band saw blades come in different standard
widths, measured from the back edge of the
blade to the tip of the tooth. Generally, wider
blades are used for ripping or making straight
cuts, such as resawing. Narrower blades are
often used when the part being cut has curves
with small radii. When cutting straight lines with
a narro w blade, the blade may hav e a tendency
to dr ift (see “Bl ade Lead” ).
Pitch
Pi tch i s measured i n “teet h per i nch” (T. P.I.) and
can be constant or variable. Figure 55 shows
blades wit h differ ent pit c hes.
Figur e 55
A fine pitch (more teeth per inch) will cut slowly
but more smoothly. A coarse pitch (fewer teeth
per inch) will c ut faster but mor e r oughly.
As a rule of thumb, the thicker the workpiece,
the c oar ser will be the bl ade pitch. If you have to
cut a hard or very brittle material, you will
probabl y want to use a bl ade wi th a fi ner pitc h in
order to get cl ean c uts.
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 sawdust and
overheat the blade.
As a general rule, try to use a blade that will
have from 6 to 12 teeth in the workpiece at any
giv en time.
Shape
Figure 56 shows common types of tooth shape,
or form. Tooth shape has an effect on cutting
rate .
Figur e 56 – B lade Tooth Shape
The Regular, or standard blade, has evenly
spaced teeth that are the same size as the
gullets, and a zero-degree rake (i.e. cutting
angle) . These off er precise, cl ean cuts at slower
rates. It is usually a good choice for cutting
curves and making c rosscut s.
The Skip ty pe has f ewer teet h and larger gull ets
with a zero rake. It allows faster cutting rates
than the Regular type, with a slightly coarser
finish. It is useful for re-sawing and ripping thick
stock, as well as cut ting soft woods.
The Hook t y pe blade has l arger t eeth and gullets
and a positive rake angle for more aggressive,
faster cutting when re-sawing or ripping thick
stock, especially har dwoods.
Variable-tooth blades combine features of the
other shapes, with tooth style and spacing
varying on the same blade. This produces
smooth cut s whil e dampening vibration.