The method used for dimensioning threads, cut into a part, depends if they are commonly used or bespoke. This tutorial will cover dimensioning custom threads and standard threads.
In the case of a bespoke thread, the machine shop will require all of the necessary dimensions to fabricate the thread. The precision of the dimensions and any GD&T tolerances will be dependent on the design requirements. The following example uses a SolidWorks toolbox component, the bolt is from the BS EN 28765 standard and is an M10x1.0 hex head bolt. To follow along download a bolt from www.mcmaster.com, and use the same procedure outlined below:
- Place front/side views of the threaded component to be dimensioned. Use the view layout tab and select either “Standard 3 view” or “model view”.
- Use smart dimensions, from the annotation tab of the CommandManager, to place all of the necessary dimensions to fabricate the component. On placement of a dimension, precision is controlled by the standard selected in the document properties of the drawing. The precision of individual dimension can be set manually after placement. Include any tolerances per your design requirements.
- Create a detail view to dimension the thread; this requirement will be dependent on the sheet size. Set the view scale such that dimensions can be clearly laid out. Tip: Place a large detail view initially, add a centerline and dimension both the minor/major diameters. Afterwards reduce the size of the detail view and set the minor/major diameter dimensions to foreshortened. To create a foreshortened dimension, click on the dimension line then right click and select “Display Options” – “Foreshorten”. Their appearance is controlled by the drawing standard in the document properties.
Refer to the Mechanitec Design tutorial series on adding/editing dimensions and tolerances for more information.
In most cases, components designed make use of existing thread standards or off the shelf components. Indicate these threads using their thread designation.
The examples above use a bolt to outline how a thread can be dimensioned on a part. In reality bolts are off the shelf components, ensure that the relevant custom properties have been filled out in the part so that they are displayed in the assembly BOM. Follow the tutorial on how to show cosmetic threads in SolidWorks for other design examples.