Blade Selection; Width; Pitch; Set - Jet JWSS-22B Operating Instructions Manual

12.0 Blade selection

Refer to Figures 31 and 32.
The following information is general in nature. The
scroller is encouraged to research specific options
to meet project needs. Note that the same
specifications may vary among manufacturers.
A wide array of blades are available for the scroll
saw. Woodworking blade sizes range from #3/0 to
#12.
Here are factors to consider when selecting a blade:
•
Type of material to be cut (hardwood,
softwood?).
•
Thickness of workpiece (thicker pieces will
require larger blades).
•
Features of workpiece (straight cuts, sweeping
curves or tight fretwork?).
These factors are important because they involve
basic concepts of blade design. There are 5 blade
features that normally vary to meet certain kinds of
sawing requirements. They are:
1.

width

2. pitch (number of teeth per inch)
3. tooth set
4. blade material
5. tooth form
12.1 Width
Width is measured from back edge of blade to tip of
tooth. Generally, wider blades are used for making
straight cuts and long curves. Narrow blades are
suited for cuts with tight corners, such as fretwork.
When cutting straight lines with a narrow blade, the
blade may have a tendency to drift (called "blade
lead").

12.2 Pitch

Pitch is measured in "teeth per inch" (TPI) and can
be constant or variable.
A fine pitch (more teeth per inch) will cut slowly but
more smoothly, and minimize vibration. A coarse
pitch (fewer teeth per inch) will cut faster but more
roughly.
Try to use a blade that will have a minimum of 3
teeth engaged in the workpiece at any given time.

12.3 Set

"Set" refers to the manner in which the blade teeth
are bent or positioned. Bending the teeth creates a
kerf that is wider than the back of the blade. This
helps the operator more easily pivot a workpiece
through curve cuts, and decreases friction between
blade and workpiece on straight cuts. Two common
sets are the straight (or alternating) and the raker.
Figure 31: blade anatomy

12.4 Material

Blades are manufactured by stamping, milling, or
grinding.
•
Stamped blades are punched out on a press
from sheet steel. The teeth are given an
alternate set to allow clearance in the kerf.
•
Milled blades are made by flattening a steel
wire, cutting the teeth through a "milling"
process, then heat-hardening the steel.
•
Ground blades have high-carbon steel teeth
which tend to hold their sharpness longer, and
provide smooth cuts.
Special styles are also available, such as twist and
spiral blades, which cut from all sides.
Most blades offered are 5 inches long; if a longer
blade is acquired the end can be snipped off to
accommodate the saw.
Optimally, a blade (and the operator's technique)
should leave smooth, clean cuts that do not require
sanding, as it is often very difficult to sand inside
cuts after they are made.
Instead of purchasing a wide assortment of styles
from the start, the scroller may find a few carefully-
selected styles will serve most of his or her needs.
The selection can be expanded as the scroller gains
experience.
18