# Mechanical: Intermittent Rotary Motion

• MetalUrge
In summary, to model the Continuous Rotary Converted into Intermittent Rotary Motion, you need to accurately measure the angles and distances between the cam, stops, and discwheel to create a precise CAD model that simulates the movement.
MetalUrge
I'm trying to virtually simulate a certain mechanical movement (#88) respect to Intermittent Rotary Motion. This is from the book '507 Mechanical Movements' written about 150 years ago.

An image of the setup is attached.

The description goes like this: Continuous rotary converted into intermittent rotary motion. The discwheel B, carrying the stops C, D, turns on a centre eccentric to the cam A. On continuous rotary motion being given to the cam A, intermittent rotary motion is imparted to the wheel B, the stops free themselves from the offset of the cam at every half revolution, the wheel B remaining at rest until the cam has completed its revolution, when the same motion is repeated.

I would love to be modeling the pieces, centering the rotational pivots with CAD standards. The problem with this is that the accuracy of the model must be such that the points of rotation and stop placements must require high precision. And since I am not so fluent with the trigonometries for mechanical requirements could someone describe the aspects to be considered while modeling the pieces. Aspects in the sense what angular trajectory measurements must be taken for each of the stops, the cam-push and the centres of rotation for the cam as well as the discwheel for this to work appropriately.

Any help and guidance would be of high value. Thanks in advance.

#### Attachments

• Cam Movement.gif
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To model this movement, you need to measure the angles of rotation and the distances between the stops and the cam. You also need to measure the distance between the center of rotation of the discwheel and the cam. The angular trajectory measurements should include the angle of rotation for the cam, the angle at which the stops move off the cam, and the angle at which they return to the cam. Finally, you need to determine the distance between the centers of rotation of the cam and the discwheel. By measuring these angles and distances accurately, you can create a CAD model that accurately simulates the intermittent rotary motion.

I would first like to commend you on your efforts to virtually simulate a mechanical movement from over 150 years ago. It is a testament to the timelessness and relevance of mechanical engineering principles.

In order to accurately model this intermittent rotary motion, there are a few aspects that need to be considered. First, the dimensions and measurements of the cam, discwheel, and stops must be accurately represented in the CAD model. This includes the diameter and thickness of the cam, the distance between the cam and discwheel, and the size and placement of the stops.

Next, the angular trajectory of each component must be carefully calculated and aligned. This can be done by using trigonometric principles to determine the precise angles at which the stops should be placed, as well as the centers of rotation for the cam and discwheel. It may also be helpful to use a specialized CAD software that allows for precise angular measurements and rotations.

Additionally, the eccentricity of the cam must be taken into account, as this is what allows for the intermittent motion. The offset of the cam should be accurately represented in the model and aligned with the stops on the discwheel.

Finally, it is important to ensure that the model is precise and accurate to the original design in order for it to function properly. This may require multiple iterations and adjustments to the dimensions and angles until the movement is accurately simulated.

In summary, modeling this mechanical movement requires attention to detail, precise measurements, and an understanding of trigonometry and rotational motion. With careful consideration of these aspects, you should be able to accurately simulate the intermittent rotary motion described in the book '507 Mechanical Movements'. Good luck with your project!

## 1. What is intermittent rotary motion?

Intermittent rotary motion is a type of motion where a rotating element moves in a start-stop manner rather than continuously. This type of motion is commonly used in mechanical systems to control the movement of various components.

## 2. What are some common examples of intermittent rotary motion?

Some common examples of intermittent rotary motion include the movement of gears, cams, and ratchets. These components are often used in mechanical systems to convert rotational motion into linear motion or to control the timing of movements.

## 3. How is intermittent rotary motion achieved?

Intermittent rotary motion is achieved through the use of mechanisms such as pawls, levers, and clutches. These mechanisms control the movement of the rotating element and allow for the intermittent start-stop motion.

## 4. What are the advantages of using intermittent rotary motion?

One of the main advantages of using intermittent rotary motion is that it allows for precise control over the movement of mechanical systems. It also allows for the conversion of rotational motion into linear motion, which is necessary for many mechanical applications.

## 5. What are the limitations of intermittent rotary motion?

One limitation of intermittent rotary motion is that it can be more complex and require more precise engineering compared to continuous rotary motion. It also may require more maintenance due to the use of mechanisms and moving parts. Additionally, intermittent rotary motion may not be suitable for high-speed applications.

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