Like I understand the concept of kickback but why cant we reverse the direction of the teeth so it kicks forward and binds the blade.
In: Engineering
Saw blades need to be curved towards the direction that they’re cutting, otherwise they will grind rather than cut.
If you were talking about reversing the direction of the blade itself, it will generally be MORE likely to kick. Think of it on a table saw; if the saw cut away from you, any catch would pull the piece away from you like a board launcher. That’s why we push into the cut; so if kickback does happen, it tends to push you away from the saw.
Then when the teeth bite the wood launched forward and sometimes pulls the operator into the blade if they’re holding on tight.
Kickback is generally not an issue with the direction of the teeth, in most cases it’s the parts of the timber and/or dust (or whatever you’re cutting) either side of the blade closing against the sides of the blade causing compression and therefore more friction.
The danger depends on the type of saw you’re using. In the case of a portable circular saw, the cutting part of the blade is moving forward, away from you. So when the blade stops due to additional friction, the saw will attempt to spin in the opposite direction. If you’re not braced for it, this causes the saw to kick back towards you, and if you’re still holding the trigger the blade starts spinning as soon as it’s free and you get cut. Keep in mind this all happens in a fraction of a second.
Table saws will generally just spit whatever you’re cutting back at you with extreme force..
The direction of the teeth is also necessary for clearing the cut of waste.
Kickback happens when the blade binds and the force (of rapidly slowing the blade and motor) either goes into the workpiece (table saw) or tool (circular saw).
If we turned the blade the other way circular saws would try to climb out of the cut and rocket off across the workpiece (see circular saw races). Additionally, if the blade rotated into the work you have to always hold the saw back from cutting deeper. As they are in use now, the force of cutting pulls the shoe of the saw into the workpiece, and if you stop pushing the saw doesn’t keep feeding.
A table saw blade turning in the direction of the cut would tent to pull in the workpiece and potentially the operator – not great.
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