Angle grinders and hand-held circular saws (“Skil Saws”) are common power tools used on construction sites and in home handy-man applications. Too often, angle grinders are converted into defective circular saws. This conversion subjects the operator to an unreasonably dangerous risk of significant personal injury.
In this article, woodworking tool expert and Professional Engineer Les Winter describes the differences between these two tools and the dangers created when circular saw blades are fitted to angle grinders.
The Dangers of Fitting a Circular Saw Blade to an Angle Grinder – Expert Article
A circular saw is used to cut wood. The teeth around the periphery of the blade chip away the wood material by excavating a trench referred to as a “kerf.” When the cut is completed, the single piece of wood is cut in two. The sawdust left behind is the material that was chipped away by the blade’s teeth.
Circular saw blades are intended to be mounted on circular saws. The following image shows the parts of a typical circular saw.
As can be seen in the image above, circular saws have two handles, an upper and lower guard and a flat base.
The guards provide a degree of protection against blade-hand contact. The handles provide the means to control the saw. The base provides a stable resting place for the saw on the workpiece and limits the depth of the blade exposed and/or embedded in the workpiece.
An angle grinder is not a cutting tool in the same sense as a circular saw. Angle grinders are fitted with abrasive wheels, not blades. These wheels operate by abrading the material they come into contact with. These wheels are not suitable for cutting wood: they have no teeth. Rather they are used to remove grout between bricks, smooth surfaces, and shorten bolts, amongst other purposes.
The following image shows a typical angle grinder fitted with an abrasive grinding wheel.
As can be seen in the image above, the abrasive wheel is largely unguarded. The “wheel guard” is a chip deflector and not a guard in the common sense. Its purpose is to direct the abrasive stream of debris generated during use away from the operator. If the wheel should shatter, the chip deflector provides some protection against the operator being struck by the thrown wheel pieces. Of special note is the absence of a base: the angle grinder has none. Consequently, unlike the circular saw, the grinder’s stability and depth of cut are both controlled only by the operator’s hands.
A dangerous use of the angle grinder is to remove the grinding wheel and replace it with a circular saw blade. Manufacturers of angle grinders prohibit this dangerous practice. The following image shows this extreme misuse.
As can seen in the image above, the angle grinder has been converted into a defective circular saw. This combination has no base plate to provide stability against vertical rotation (tipping), or horizontal twisting movement. The lack of a base plate will allow the blade to sink downward into the cut in an uncontrolled manner. Any vertical or horizontal twisting of the tool will cause the blade teeth to become jammed in the kerf. If this jamming is significant enough, the tool will “kick back” towards the operator with great force. The exposed blade can cause significant injuries as the uncontrollable tool flies backwards and strikes the operator.
For these reasons, angle grinders must never be fitted with circular saw blades.
WOODWORKING TOOLS INVESTIGATIONS
Our experts are regularly retained in casework involving lacerations, amputations, and deaths that are associated with the use or misuse of saws and other woodworking tools. The scope of our investigations can include equipment operation and maintenance as well as various safety features, such as guards, protective equipment, and flesh sensing technology units (sawstop). They can also assess the roles of the various parties who may be involved in a worker using a piece of equipment.
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Woodworking Machinery Expert & Electrical Engineer
Les Winter is a professional engineer who specializes in table saw, miter saw, band saw, circular saw (“skilsaw”) and other woodworking machinery-related injuries. As a professional engineer and an accomplished woodworker, he is regularly retained in casework involving equipment operations and maintenance as well as various other safety aspects, such as equipment modifications and safety guards, including sawstop and flesh sensing technology units.