Egg grader with electronic scale and servos - how do I size the DC Motor?

Other Hardware Motors, Mechanics, Power and CNC
1

Hello, I am trying to develop an egg grader machine, with its parts being made in a 3d printer with a metal chassis. I would like to learn how to size the DC Motor needed to make the circular movement.

Screen Shot 2022-04-15 at 12.20.21 PM
Screen Shot 2022-04-15 at 12.20.21 PM974×699 47.2 KB

As the picture shows, it will be a simple machine:

  1. There is a ramp to load the eggs, this ramp will end up in the scale, with something to control when the egg goes to the scale according to the movement of the system;

  2. The eggs are transported from the scale to positions #1 to #6 and are expelled from this position in accord to its grade (weight) by a servo motor;

  3. The transport from each position to another is made in a circular motion provided by a structure supported by two pulleys joined by a belt, being one of those pulleys attached to a DC Motor;

Pretty much I am going to base all distances, calculations, etc, in the measurements of an egg.

As far as I could plan, here are some numbers:

  1. Weight of the moving system (structure to hold the eggs, with the eggs) 1000g or less
  2. Distance from motor axle to the structure that support the eggs will go (the Radius if you will) 12 cm

Could you please help me to calculate the DC Motor sizing, which pulleys to buy (I guess it depends on axle diameter) and belt? I would like to learn, so examples would be nice.

I know the electronics part, how to draw in 3D the parts, etc. I only need the DC Motor part that I am having a hard part to learn.

Thank you,

Rom Pereira

2

Screen Shot 2022-04-15 at 12.54.16 PM
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Drawing to understand how I measure the distance, sorry about it.

3

The most straightforward way to size the motor is to build a prototype for the belt, pulleys, etc., leaving a shaft accessible for mounting the motor, and measure the force/torque required to move it at the correct speed, while loaded as in the actual application.

Buy a motor that fits the space and can provide at least twice the required torque.

Tutorial on force and torque: Pololu - Force and torque

Otherwise, you have to estimate with reasonable accuracy the friction in all the bearings, belt load, etc.

4

Hello and thank you for reading my post.

At 47 years of age, I know my limitations. I do not want to learn the whole theory - trust me I already researched about this a bit - I know how to calculate the torque, the formulas, etc, but if I start buying different sets of pulleys, DC Motors, belts, etc, it will become a quite expensive project.

Instead of spending a lot of money doing that, it would be nice to have somewhat an indication of someone who knows this and could point me in the right direction.

If you may, please, help out.

Thank you,

Rom

5

someone who knows this

That someone has to have measurements made on the machine you have built, in order to help out.

6

Also I forgot to mention speed in the original post. I would like to grade 1 egg per second. I found some DC Motors that do, with reduction, 100 RPM.

DC MOTOR 100 RPM

7

Sure thing. Which measurements do you need?

8

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