Investigation Guideline

Appendix 55
December 7, 1987
PORTABLE CIRCULAR SAWS
I.

INTRODUCTION
A.

Background Information

Estimates from the NEISS data for 1986, indicate about
41,000 emergency room treated injuries occurred involving either
powered portable circular saws, or powered stationary circular
saws. These injuries resulted in hospitalization rates that were
estimated at almost twice the average for all injuries reported
through the NEISS system. From 1984 to 1986, a yearly average of
10 deaths (excluding electrocutions) was reported to CPSC
associated with powered circular saws.
Hazards associated with these saws involved blade contact,
kickback, inadvertent starting, and thrown objects. Some
contributing factors appear to be location of switches, blade
guard functions, and pinching of material being cut.
We plan to study in detail all accidents associated with
operating portable circular saws, for the purpose of evaluating
the effectiveness of existing voluntary standards.
B.

Study Description

Include all incidents of injury involving portable circular
saws in active operation. This will include incidents of blade
contact, being struck by thrown objects, clothing being caught in
moving parts, or contact with other non-moving surfaces or parts.
Incidents not to be included would involve those where the saw is
not in operation, such as walking by and hitting the saw, or
other injuries not related to saw use or maintenance.
Figure 1 of attachment 1 illustrates the configuration of
the typical portable circular saw. This power tool is generally
electrically powered. it is designed to cut sheet material
(plywood, masonite, particle board, etc.), planks and dimensional
material (2x4, 2x6, 4x4, etc.), primarily wood.
A special configuration of the portable circular saw
occasionally encountered in consumer use is the Worm-drive Saw.
This saw differs from the typical circular saw in appearance and
in the design of the blade drive system. In appearance, the
circular blade on a worm-drive saw is located well forward of
blade location on the typical circular saw. As the name
indicates, a worm gear drive system is used to transfer the motor
torque to the driven blade.

In addition to the features illustrated in Figure 1,
circular saws may also have accessories such as rip guides,
protractor gauges and crosscut guides for use during specific
cutting operations.
the saw blade on the circular saw is readily removable and a
wide variety of blade designs have been developed both for
specific cutting operations and for various materials in addition
to wood. Figure 2 presents information on Typical Blade Types
and their usage.
C.

Specific Items of Interest

Provide all information on saw brand, model, age, condition,
type of blade, safety features, location of controls/switches,
and consumer use patterns. Photograph saw, environment, and a
reenactment of victim's position at the time of accident. This
guideline was developed to provide general assistance when
conducting investigations related to power saw incidents. Do not
limit your responses solely to the information requested int his
guideline. If any other pertinent information is discovered,
include it!

II.

INSTRUCTIONS FOR COLLECTING SPECIFIC INFORMATION
A.

Synopsis

Provide a complete and concise account of the accident
including the product(s) involved, who was injured, what the
injury was, where the accident occurred, and the severity of the
injury.
B.

Description of the Product
1.

Task

·

Explain in a step-by-step manner the tasks
required to set up and use the saw (i.e., plug in
wall, turn on switch, adjust blade, etc.). See
Figure 3 on Types of Saw Cuts.

·

Describe in detail the exact task being performed
by the victim (i.e., ripping, crosscutting, miter
cutting, bevel crosscutting, bevel ripping).

·

Provide details of victim's exact position while

performing the task. This should include position
of hands, feet, and relation between saw and
material being cut.
·

Indicate if any problems existed with material
being cut, which may have contributed to the
accident sequence (i.e., knots in the wood, board
bouncing or shifting, binding, etc.).

·

Determine width, length, thickness and type of
stock being cut.

·

Indicate how stock was supported, and how stable.

·

Specify if any safety devices were being used at
the time of the accident, such as a lower blade
guard or an off-on safety switch. If not used,
state reason. If used, did any safety device
malfunction? How?

2.

Product

·

Give complete description of the saw; include
brand, model, age (motor horsepower, amps, and
rpms), general condition, location and type
controls, and if any modification or repairs were
made to the saw. Include brand and type of blade.

·

List presence of all safety devices on the saw,
and their condition.

·

Pay particular attention to the blade guard, tell
if it was in good condition and operating as
intended. (If not, give reason--spring broken,
gummed up, dirty, etc.)

·

Provide diameter and condition of blade being used
(sharp, dull, teeth missing, rust or residue on
blade, etc.).

·

State type of blade used (crosscut, rip,
combination, etc.). Also, state number of teeth
and diameter of blade (see Figures 2 and 2A).

·

State whether the plate/shoe of the saw was
adjusted to a proper blade depth for the thickness
of the stock being cut.

·

Indicate if saw has a blade bolt that functions as
a blade clutch. If present, was the blade bolt
adjusted too tight, adjusted too loose, or
adjusted correctly to allow blade to slip if an
obstruction occurs.

·

Explain how blade angle was adjusted.

·

Indicate the location of the off-on switch,
relative to the location of the blade.

·

List location and wording of any safety, warning,
caution or operating labels or information
displayed on saw.

·

State if the saw came assembled, or had to be
assembled. If not assembled, indicate who
assembled the saw and if set-up instructions, such
as squaring and aligning the blade were followed.

·

Indicate any saw preparation for this operation,
for example, mounted new blade on saw.

·

Indicate what maintenance was performed on the saw
and by whom.

·

Indicate any modifications/repairs to saw.

C.

Description of Accident Environment

·

Describe sequence of events leading to the accident,
including all relevant information on environmental
factors, usage or any abuse, and location of saw.

·

Detail aspects of lighting, its location and intensity.

·

Provide details of area around saw, considering free
movement for operator.

·

Re-enact the accident scenario. Give a complete and
concise description of the accident, including events
before the accident, during the accident and after the
accident.

D.

Description of the Injured Person(s)

·

Detail information on user's experience* with,
knowledge of the saw (e.g., advise whether warning
labels or instructions were read and understood).

*
User experience is an area which needs some careful
attention. In most cases, the victim has used the saw many times
before without incident. Probe with general questions to
determine the victim's general condition, and determine what was
different on the day of the accident. Consider fatigue, lack of
attention, hurrying, etc.
·

Have victim describe his/her impressions relating to
the saw's weight (heavy, light, hard to balance, etc.).

·

Ask questions concerning the user's feelings towards
the saw and task being performed (e.g., consider afraid
of saw, feels it dangerous, thinks nothing about it,
respects its potential for injury and is careful in its
use, etc.).

·

Describe injuries sustained, their severity, treatment
required, and prognosis for recovery.

·

Give victim's height, weight, age, and general health.

·

State if any protective clothing or equipment was used,
and what type.

E.

Product Safety Standards

·

Check all labeling for any indications (e.g., UL or
other listing of certifications) that the saw involved
in the accident meets a voluntary standard. Thoroughly
document (with photographs as appropriate) all such
indications. If no indications of applicable standards
are found, include a statement indicating this in the
investigation report.

·

If there are indications of an applicable voluntary
standard, include in the report all available
information which might help determine whether the saw
violates any applicable section of the standard.

III. INSTRUCTIONS FOR PHOTOGRAPHING AND/OR
DIAGRAMING ACCIDENT SCENE AND FACTORS
RELATED TO THE ACCIDENT

IV.

·

Photograph the saw showing front, side, and top views
and how the stock was supported.

·

Provide close-up photos of labels, controls, safety
devices or guards, and off-on switches.

·

Have victim pose for a photo which depicts his/her
position, as well as the position of the material being
cut, at the time of the accident.

·

Include close-up of photo of the blade involved, which
shows the type and size of the teeth.

INSTRUCTIONS FOR OBTAINING SAMPLES AND DOCUMENTS
RELATED TO THE INVESTIGATION
·

Photocopy the owner's manual and attach it to the
report.

·

Complete any unanswered questions from the telephone
investigation, also verify the responses given
(annotate discrepancies on form).

·

Obtain all information requested in guideline and
attach the guideline to the report.