GD&T (Geometric Dimensioning and Tolerancing) is an important piece of Mechanical Drawing. With DraftSight it's very easy to add tolerances in your drawings. With just two commands and the power of the Properties Bar you can create the necessary tolerances for your drawing.
DraftSight Commands:
LEADER: Creates the arrows that connect the tolerances or datum identifiers with the appropriate drawing entities
TOLERANCE: With this command you can specify type, value, material condition and datum for your tolerances.
And with the Properties Bar you can change a variety of properties of Leaders and Tolerances like type and size of arrows, text style and height and much more in order to make these entities to fit better with your drawing.
The following example will show you how to add and modify tolerances in a drawing.
The example drawing without Tolerances, Datum Identifiers and Leaders
First you have to create the desired tolerances. So use the TOLERANCE command that you can find under the Dimension pull-down menu. In this example you have to use this command 4 times. 3 for the creation of the 3 Datum Identifiers and 1 for the creation of the needed Position Tolerance.
The TOLERANCE command under the Dimension pull-down menu.
-For the creation of a Datum Identifier use the TOLERANCE command and enter with keyboard a capital letter under the Datum Identifier section of the Tolerance Dialog Box. Then press OK and use your mouse to place the created Datum Identifier in the appropriate location. In this example letters A, B and C will be used as Datum Identifiers.
Creating a Datum Identifier
-For the creation of the Position Tolerance use the TOLERANCE command again and specify type, value and datums. In this example you have to use as type the Position Tolerance from the Pull down menu, as value you have to enter with keyboard 0.02, as first datum the capital letter C, as second datum the capital letter A and as third datum the capital letter B. Then press OK and use your mouse to place the created tolerance in the appropriate location.
Creating the Position Tolerance.
After that, you have to create the necessary Leaders in order to connect the Tolerance and the Datum Identifiers boxes with the appropriate drawing entities. Use the LEADER command under the Dimension pull-down menu to create the necessary leaders. In this example you have to create 4 Leaders, 3 for the Datum Identifiers and 1 for the Position Tolerance.
The LEADER command under the Dimension pull-down menu.
-You have to use your mouse in order to create a Leader. As first point of the Leader always select a point of the reference drawing entity because the arrow of the Leader will be created in this point. As last point of the Leader select the midpoint of the appropriate side of the Datum Identifier or Tolerance box.
Now you can modify the properties of the created Tolerances, Datum Identifiers and Leaders with the Properties Bar. In this example a necessary modification is the arrow type of the Leaders of Datum Identifiers. Select all the Leaders of the Datum Identifiers and change the Arrow type to "Datum triangle filled". With the Properties Bar you can make a lot of other modifications (Text Height and Style, Precision etc)
Changing the Arrow type with the Properties Bar.
The final result.
Tip: You can combine the LEADER and TOLERANCE commands by changing the settings of the LEADER command. Just type "s" in the Command line after executing the LEADER command and press enter. In the "Annotations" tab select "Tolerance" as type. With this change after the completion of the LEADER command the TOLERANCE command will be executed automatically.
LEADER command settings.
Relative Documentation and Standards:
ASME Y14.5: Dimensioning and Tolerancing, Engineering Drawing and Related Documentation Practices.
ASME Y14.41: Digital Product Definition Data Practices.
ISO 1101: Geometrical Product Specification (GPS) - Geometrical Tolerancing - Tolerances of form, orientation, location and run-out.
