How Much Motor Power is Needed for a DIY Drum Coffee Roaster?

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Discussion Overview

The discussion centers around determining the appropriate motor power needed for a DIY drum coffee roaster, specifically considering the drum size, load, rotation speed, and friction factors. Participants explore various aspects of motor selection, including torque and horsepower requirements, as well as practical approaches to estimating power needs.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Héctor seeks guidance on how to calculate the motor power required for a drum coffee roaster with specific dimensions and load.
  • One participant suggests that any motor can turn the drum, but emphasizes the importance of understanding the desired speed and the friction encountered, particularly from the tumbling beans.
  • Another participant notes the need for speed control and references a similar device that drew 16 Amps at 110 volts, indicating a potential power requirement.
  • Héctor expresses concern about not underutilizing power or money and requests specific horsepower or torque values for motor selection.
  • A later reply reiterates that the motor size largely depends on friction, which is difficult to estimate without empirical data.
  • Participants propose looking at existing coffee roasters for motor specifications or conducting personal experiments to measure power needs once the roaster is built.

Areas of Agreement / Disagreement

Participants generally agree that friction is a critical factor in determining motor size, but there is no consensus on specific horsepower or torque values needed. Multiple approaches to estimating power requirements are discussed, indicating ongoing uncertainty.

Contextual Notes

Participants acknowledge the challenge of estimating friction without empirical data, which may limit the ability to provide definitive motor specifications. The discussion also references the potential for using parts from similar devices, such as electric clothes dryers.

Hemipatuca
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Hello, My name is Héctor and I love coffee, I'm working on a diy drum coffee roaster. Drum + load= 50 pounds, rotation needed = 10-60 Rpm, length from 20 to 30 cm. How can I determine the motor power that can turn my drum? Can someone help me please?
Thank you in advance
 
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Any power has the potential to turn that drum.
What you need to know is how fast you want to spin it up and what type of friction it will encounter.

A main source of friction is the tumbling of the beans.
I would track down the service manual to a commercial roaster similar in size to the one you are using to find out what they are using.

A quick survey didn't show me anything specific. But one device similar in size to yours (perhaps a somewhat smaller) drew 16 Amps at 110 volts.

You're going to need to be concerned about speed control as well.
 
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Thank you for your reply, I'm aware that there are a lot of motors that can work but I don't want to underutilize power nor money. I would like to know how many hps or torque is needed to choose the correct one.

Thank you again
 
Hemipatuca said:
Thank you for your reply, I'm aware that there are a lot of motors that can work but I don't want to underutilize power nor money. I would like to know how many hps or torque is needed to choose the correct one.

I think you missed @.Scott 's point. The size of the motor depends mostly on friction. You (and we) have no way to estimate how much friction.

Therefore, your best approach is to see what size motors other coffee roasters use. The manufacturers of those other roasters may have done experiments to measure the friction.

You other possibility is to do your own experiments. Build the coffee roaster and try spinning it at the desired speed. Measure how much power that takes, and use that number to select the optimum motor.
 
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Hemipatuca said:
Summary: DIY coffee roaster

Reference https://www.physicsforums.com/threads/force-needed-to-rotate-a-drum.915197/

Hello, My name is Héctor and I love coffee, I'm working on a diy drum coffee roaster. Drum + load= 50 pounds, rotation needed = 10-60 Rpm, length from 20 to 30 cm. How can I determine the motor power that can turn my drum? Can someone help me please?
Thank you in advance
I note in passing that these requirements are not dissimilar to a small electric clothes dryer. Might be a source for parts/ ideas.
 

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