249

In This Chapter

15

Calculating Chains

In this AutoCAD

®

Mechanical 6 tutorial, you calculate a

chain length, and insert sprockets and chain links into

a drawing.

■

Performing a length calculation

■

Optimizing the chain length

■

Inserting Sprockets

■

Inserting a Chain

250

|

Chapter 15

Calculating Chains

Key Terms

Term

Definition

partition

Distance in mm or inches between centers of adjacent joint members. Other
dimensions are proportional to the pitch. Also known as pitch.

pitch diameter

The diameter of the pitch circle that passes through the centers of the link pins as
the chain is wrapped on the sprocket.

roller chain

A roller chain is made up of two kinds of links: roller links and pin links alternately
and evenly spaced throughout the length of the chain.

sprocket

A toothed wheel that transfers the power from the chain to the shaft or the other
way round.

Chain Calculation

|

251

Chain Calculation

Before you begin this tutorial exercise, be sure the ISO standard parts are
installed on your system.

First, load the initial drawing.

To open a drawing

1

Open the file tut_ex13 in the acadm\tutorial folder.

Menu

File ➤ Open

Command

OPEN

2

Zoom in to the chain housing.

Menu

View ➤ Zoom ➤ Window

Command

ZOOM

3

Respond to the prompts as follows:

Specify first corner:

Specify first corner point (1)

Specify opposite corner:

Specify second corner point (2)

The drawing contains a chain housing, sprocket positions, and points.

Save your file under a different name or to a different directory to preserve
the original tutorial file.

252

|

Chapter 15

Calculating Chains

Performing Length Calculations

First, you calculate the required length of the chain.

To perform a length calculation

1

Start the Length Calculation command.

Menu

Content ➤ Chains / Belts ➤ Length Calculation

Command

AMCHAINLENGTHCAL

2

In the Belt and Chain Length Calculation dialog box, choose Library.

3

In the Library, select ISO 606 metric.

Chain Calculation

|

253

4

In the Select Part Size dialog box, specify:

Standard:

ISO 606 - 05B - 1

Choose OK.

5

In the Belt and Chain Length Calculation dialog box, choose OK, and
respond to the prompts as follows:

Specify 1st point for tangent or [Undo] <exit>:

Select circle a (1)

Specify 2nd point for tangent:

Select circle c (2)

Specify 1st point for tangent or [Undo] <exit>:

Select circle c (3)

Specify 2nd point for tangent:

Select circle b (4)

Specify 1st point for tangent or [Undo] <exit>:

Select circle b (5)

Specify 2nd point for tangent:

Select circle a (6)

Specify 1st point for tangent or [Undo] <exit>:

Press

ENTER

Select circle to store tangents:

Select circle a

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|

Chapter 15

Calculating Chains

The tangent definition is finished, and the length of the chain is calculated.
Because the length is divided into whole numbers of links, one sprocket has
to be moved to achieve such a length.

6

Continue responding to the prompts as follows:

Select pulleys or sprockets to be moved. Select objects:

Select circle b

Select objects:

Press

ENTER

Specify base point of displacement:

Select the center of circle b

Specify second point of displacement:

Select the center of the cross (8)

Select pulleys or sprockets to be moved.
Select objects:

Press

ENTER

AutoCAD has calculated the new length, which is still not a multiple of the
chain division:

Number of links in chain: 121

Distance to next link: 6.88567 mm

Length:974.8857

NOTE

You can view the results by resizing the command line or opening the

AutoCAD Text Window using F2.

Therefore, the chain arrangement has to be optimized.

Save your file.

Optimizing the Chain Length

Now, optimize the chain length.

To optimize the chain length

1

Start the Length Calculation command.

Menu

Content ➤ Chains / Belts ➤ Length Calculation

Command

AMCHAINLENGTHCAL

Chain Calculation

|

255

2

In the Belt and Chain Length Calculation dialog box, check Auto Optimiza-
tion, Move, and specify:

Required number of links:

122

Choose OK.

3

Respond to the prompts as follows:

Select pulleys or sprockets to be moved.
Select objects:

Select the relocated circle b

Select objects:

Press

ENTER

Specify direction angle to move:

Enter 90

Sprocket b is moved until a chain length of 122 links is achieved.

4

In the Belt and Chain Length Calculation dialog box, choose Cancel, to
cancel the optimization.

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|

Chapter 15

Calculating Chains

Now, your drawing looks like this:

Save your file.

Inserting Sprockets

Now, insert the sprockets.

To insert a sprocket

1

Start the Draw Sprocket/Pulley command.

Menu

Content ➤ Chains / Belts ➤ Draw Sprocket/Pulley

Command

AMSPROCKET

2

In the Pulleys and Sprockets dialog box, specify:

Number of teeth:

21

Number of Teeth to Draw:

21

Choose OK.

Chain Calculation

|

257

3

Respond to the prompts as follows:

Specify center of wheel:

Select the center of circle a

The sprocket is inserted into the drawing. Now, insert the next two sprockets.

4

Start the Draw Sprocket/Pulley command again.

Menu

Content ➤ Chains / Belts ➤ Draw Sprocket/Pulley

Command

AMSPROCKET

5

In the Pulleys and Sprockets dialog box, specify:

Number of teeth:

13

Number of Teeth to Draw:

13

Choose OK.

6

Respond to the prompts as follows:

Specify center of wheel:

Select the center of circle b

7

Start the Draw Sprocket/Pulley command again.

Menu

Content ➤ Chains / Belts ➤ Draw Sprocket/Pulley

Command

AMSPROCKET

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|

Chapter 15

Calculating Chains

8

In the Pulleys and Sprockets dialog box, specify:

Number of teeth:

51

Number of Teeth to Draw:

3

Insertion Angle for Sprocket/Pulley:

180

Choose OK.

9

Respond to the prompts as follows:

Specify center of wheel:

Select the center of circle c

The last sprocket is inserted as a simplified representation with only three
teeth, as specified in the dialog box.

Now, your drawing looks like this:

Save your file.

Chain Calculation

|

259

Inserting Chains

Finally, insert a chain.

To insert a chain

1

Start the Draw Chain/Belt Links command.

Menu

Content ➤ Chains / Belts ➤ Draw Chain/Belt Links

Command

AMCHAINDRAW

2

In the Draw Chain/Belt dialog box, specify:

Number of Links to Draw:

122

Choose OK.

3

Respond to the prompts as follows:

Select polyline and starting point:

Select the polyline near point 9

Please wait... calculating number of chain links
Number of links in chain: 122

Distance to next link: 0 mm

Please wait... calculating number of chain links
Is position of link correct [Yes/No] <Yes>:

Press

ENTER

The chain is inserted.

260

Your drawing looks like this:

This is the end of this tutorial chapter.
Save your file.

249

In This Chapter

15

Calculating Chains

In this AutoCAD

®

Mechanical 6 tutorial, you calculate a

chain length, and insert sprockets and chain links into

a drawing.

■

Performing a length calculation

■

Optimizing the chain length

■

Inserting Sprockets

■

Inserting a Chain

250

|

Chapter 15

Calculating Chains

Key Terms

Term

Definition

partition

Distance in mm or inches between centers of adjacent joint members. Other
dimensions are proportional to the pitch. Also known as pitch.

pitch diameter

The diameter of the pitch circle that passes through the centers of the link pins as
the chain is wrapped on the sprocket.

roller chain

A roller chain is made up of two kinds of links: roller links and pin links alternately
and evenly spaced throughout the length of the chain.

sprocket

A toothed wheel that transfers the power from the chain to the shaft or the other
way round.

Chain Calculation

|

251

Chain Calculation

Before you begin this tutorial exercise, be sure the ISO standard parts are
installed on your system.

First, load the initial drawing.

To open a drawing

1

Open the file tut_ex13 in the acadm\tutorial folder.

Menu

File ➤ Open

Command

OPEN

2

Zoom in to the chain housing.

Menu

View ➤ Zoom ➤ Window

Command

ZOOM

3

Respond to the prompts as follows:

Specify first corner:

Specify first corner point (1)

Specify opposite corner:

Specify second corner point (2)

The drawing contains a chain housing, sprocket positions, and points.

Save your file under a different name or to a different directory to preserve
the original tutorial file.

252

|

Chapter 15

Calculating Chains

Performing Length Calculations

First, you calculate the required length of the chain.

To perform a length calculation

1

Start the Length Calculation command.

Menu

Content ➤ Chains / Belts ➤ Length Calculation

Command

AMCHAINLENGTHCAL

2

In the Belt and Chain Length Calculation dialog box, choose Library.

3

In the Library, select ISO 606 metric.

Chain Calculation

|

253

4

In the Select Part Size dialog box, specify:

Standard:

ISO 606 - 05B - 1

Choose OK.

5

In the Belt and Chain Length Calculation dialog box, choose OK, and
respond to the prompts as follows:

Specify 1st point for tangent or [Undo] <exit>:

Select circle a (1)

Specify 2nd point for tangent:

Select circle c (2)

Specify 1st point for tangent or [Undo] <exit>:

Select circle c (3)

Specify 2nd point for tangent:

Select circle b (4)

Specify 1st point for tangent or [Undo] <exit>:

Select circle b (5)

Specify 2nd point for tangent:

Select circle a (6)

Specify 1st point for tangent or [Undo] <exit>:

Press

ENTER

Select circle to store tangents:

Select circle a

254

|

Chapter 15

Calculating Chains

The tangent definition is finished, and the length of the chain is calculated.
Because the length is divided into whole numbers of links, one sprocket has
to be moved to achieve such a length.

6

Continue responding to the prompts as follows:

Select pulleys or sprockets to be moved. Select objects:

Select circle b

Select objects:

Press

ENTER

Specify base point of displacement:

Select the center of circle b

Specify second point of displacement:

Select the center of the cross (8)

Select pulleys or sprockets to be moved.
Select objects:

Press

ENTER

AutoCAD has calculated the new length, which is still not a multiple of the
chain division:

Number of links in chain: 121

Distance to next link: 6.88567 mm

Length:974.8857

NOTE

You can view the results by resizing the command line or opening the

AutoCAD Text Window using F2.

Therefore, the chain arrangement has to be optimized.

Save your file.

Optimizing the Chain Length

Now, optimize the chain length.

To optimize the chain length

1

Start the Length Calculation command.

Menu

Content ➤ Chains / Belts ➤ Length Calculation

Command

AMCHAINLENGTHCAL

Chain Calculation

|

255

2

In the Belt and Chain Length Calculation dialog box, check Auto Optimiza-
tion, Move, and specify:

Required number of links:

122

Choose OK.

3

Respond to the prompts as follows:

Select pulleys or sprockets to be moved.
Select objects:

Select the relocated circle b

Select objects:

Press

ENTER

Specify direction angle to move:

Enter 90

Sprocket b is moved until a chain length of 122 links is achieved.

4

In the Belt and Chain Length Calculation dialog box, choose Cancel, to
cancel the optimization.

256

|

Chapter 15

Calculating Chains

Now, your drawing looks like this:

Save your file.

Inserting Sprockets

Now, insert the sprockets.

To insert a sprocket

1

Start the Draw Sprocket/Pulley command.

Menu

Content ➤ Chains / Belts ➤ Draw Sprocket/Pulley

Command

AMSPROCKET

2

In the Pulleys and Sprockets dialog box, specify:

Number of teeth:

21

Number of Teeth to Draw:

21

Choose OK.

Chain Calculation

|

257

3

Respond to the prompts as follows:

Specify center of wheel:

Select the center of circle a

The sprocket is inserted into the drawing. Now, insert the next two sprockets.

4

Start the Draw Sprocket/Pulley command again.

Menu

Content ➤ Chains / Belts ➤ Draw Sprocket/Pulley

Command

AMSPROCKET

5

In the Pulleys and Sprockets dialog box, specify:

Number of teeth:

13

Number of Teeth to Draw:

13

Choose OK.

6

Respond to the prompts as follows:

Specify center of wheel:

Select the center of circle b

7

Start the Draw Sprocket/Pulley command again.

Menu

Content ➤ Chains / Belts ➤ Draw Sprocket/Pulley

Command

AMSPROCKET

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|

Chapter 15

Calculating Chains

8

In the Pulleys and Sprockets dialog box, specify:

Number of teeth:

51

Number of Teeth to Draw:

3

Insertion Angle for Sprocket/Pulley:

180

Choose OK.

9

Respond to the prompts as follows:

Specify center of wheel:

Select the center of circle c

The last sprocket is inserted as a simplified representation with only three
teeth, as specified in the dialog box.

Now, your drawing looks like this:

Save your file.

Chain Calculation

|

259

Inserting Chains

Finally, insert a chain.

To insert a chain

1

Start the Draw Chain/Belt Links command.

Menu

Content ➤ Chains / Belts ➤ Draw Chain/Belt Links

Command

AMCHAINDRAW

2

In the Draw Chain/Belt dialog box, specify:

Number of Links to Draw:

122

Choose OK.

3

Respond to the prompts as follows:

Select polyline and starting point:

Select the polyline near point 9

Please wait... calculating number of chain links
Number of links in chain: 122

Distance to next link: 0 mm

Please wait... calculating number of chain links
Is position of link correct [Yes/No] <Yes>:

Press

ENTER

The chain is inserted.

260

Your drawing looks like this:

This is the end of this tutorial chapter.
Save your file.