School of Hard Rocks

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Rock Tumbling Electricity


As you get started into rock tumbling it is inevitable that the question arises as to how much electricity you are using.  Well, the machines do run constantly and they do an awful lot of work.  Electric bills are growing like most other energy bills.  It is good to ask the question and to give it careful consideration.  The really good news is that rock tumblers donít use that much energy.


My favorite, the Thumler Model B, uses 0.8 amps at 115 volts.  The Thumler Model A-R2 and the Thumler Model A-R12 both use 0.54 amps at 115 volts.


As we prepare to quantify our energy usage letís review some definitions.  A watt is a unit of power.  It measures the rate of energy conversion or of doing work.  In electromagnetism, one watt is the rate at which work is done when one ampere (A) of current flows through a potential difference of one volt (V).


watts = amps * volts

A kilowatt-hour, kWh, is a unit of energy equal to 1000 watt hours.  This is the unit used by the utility companies as they charge us for power.


As a basis for comparison we will use a 60 watt light bulb.  This 60 watt light bulb burning constantly for 24 hours uses 1.44 kWh of electricity.


kWh per day for 60 W bulb

At 10 cents a kWh, you would spend about 15 cents running the 60 watt light bulb continuously for one day.


Letís look first at the Models A-R2 and A-R12.  They draw 0.54 amps of current.  We first need to find the wattage of the motor,


wattage of A-R2 and A-R12

Over the course of 24 hours they use 1.49 kWh of electricity.


kWh per day for A-R2 or A-R12

At the rate used earlier of 10 cents per kWh, you would spend about 15 cents each day you run an A-R2 or an A-R12.


Now the Model B draws 0.8 amps of current.  Finding the wattage of this motor,


wattage for Model B

Over the course of 24 hours a Model B uses 2.21 kWh of electricity.


kWh per day for Model B

At the rate used earlier of 10 cents per kWh, you would spend about 22 cents each day you run the Model B.