WEBVTT - Why is a circular saw louder than a table saw?

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<v Speaker 1>Welcome to brain Stuff from house stuff works dot com

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<v Speaker 1>where smart happens. Hi Am Marshall Brain with today's question,

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<v Speaker 1>why is a table saw so quiet but a portable

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<v Speaker 1>circular saw is so loud? A circular saw makes a

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<v Speaker 1>lot more noise because of the type of motor it uses.

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<v Speaker 1>The circular saw has a universal motor in it, and

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<v Speaker 1>this type of motor is extremely noisy. Universal motors are

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<v Speaker 1>called universal because they are happy to run off of

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<v Speaker 1>either a C or D C electric power. Circular saws

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<v Speaker 1>use brush type universal motors. Vacuum cleaners, routers, and electric

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<v Speaker 1>drills also use universal motors. These motors produce so much

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<v Speaker 1>noise because the brushes rub on a slotted armature. In

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<v Speaker 1>circular saws and drills, you also have gear train noise.

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<v Speaker 1>Something like a radial arm saw or a table saw

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<v Speaker 1>that you have in your garage uses an induction motor instead.

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<v Speaker 1>Induction motors run only on a C power and they

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<v Speaker 1>do not use brushes. That's the main reason why they're

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<v Speaker 1>so quiet. They also run slower and usually use a

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<v Speaker 1>belt drive instead of a gear train. Manufacturers use universal

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<v Speaker 1>motors because they are smaller and much lighter than induction motors.

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<v Speaker 1>A three quarter horsepower induction motor might weigh twenty pounds.

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<v Speaker 1>A three quarter horsepower universal motor might weigh two or

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<v Speaker 1>three pounds. The weight difference is huge. A circular sty

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<v Speaker 1>would be almost unusable if it contained an induction motor.

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<v Speaker 1>If you have a quiet appliance, it probably has an

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<v Speaker 1>induction motor inside it. Ceiling fans and refrigerator compressors both

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<v Speaker 1>use induction motors to keep them quiet in your house.

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<v Speaker 1>It's always a good idea to where ear protection when

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<v Speaker 1>using a loud power tools. Even the quiet radial arm

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<v Speaker 1>SAD gets pretty noisy as soon as it starts chewing

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<v Speaker 1>through a piece of wood. Do you have any ideas

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<v Speaker 1>or suggestions for this podcast? If so, please send me

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<v Speaker 1>an email at podcast at how stuff works dot com.

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