SolidWorks is heavily based around sketching your initial idea, then defining it at a later time. This parametric design system allows the flexibility to go back and change one dimension, with all of the others being automatically updated themselves. SolidWorks uses two major methods of defining a sketch, dimensions and relations. In this post, I will discuss just the dimensions as they are the most important when starting with SolidWorks.
A dimension in SolidWorks refers to the length or angle of a particular part of your sketch. This can be as simple as saying one of the edges of a rectangle is 200mm long, or that one of the angles of a triangle is at 30 degrees. I can also relate to multiple parts, for instance, the position of a corner based upon the edge of another point. The best way to illustrate how dimensions work is to do an example, which I will show below.
In the example above we have a simple rectangle with 4 dimensions, two of these dimensions are defining the length and height of the rectangle and the other two are defining its location. You will also note that the sketch here is all black, whereas all the previous sketches that have been done were all blue. If the sketch is black it means that it is fully defined, and therefore will not change unless you modify the dimension values.
Creating dimensions in SolidWorks is incredibly easy as it has a tool called Smart Dimension which can automatically determine which kind of dimension you need. The tool can be seen in the top left of the image, next to the Exit Sketch command. Once you have the smart dimension selected, simply click on a line or point of your sketch, if you select a line it will automatically give you the dimension of this line. If that was what you were after (a length dimension) then you can simply click again which will bring up the Modify toolbar, this is where you can set/change the dimension. If you were after a positioning dimension, rather than clicking again in an arbitrary point click on the next line or point to give you the length between each click. You will then need to click again to accept the dimension, again the Modify toolbar will appear and you can enter in the dimension you wish.
Note: At any point, if you press the ESC button on your keyboard it will cancel the current dimension, and if you press it again it will cancel the entire smart dimensioning tool.
Below you can see another slightly more complicated example which includes a variety of different dimension. All of these were done using the same Smart Dimension tool, this makes defining sketches so easy as you do not need to swap between tools. This can be seen clearly as there are three diameter dimensions, all with the correct symbol as well as an angle with the appropriate degrees symbol.
The process taken to create the above sketch goes as follows:
- Draw three circles in roughly where you want them, two with their centres at the origin and one in the top left
- Draw a centerline from the smaller circle to the origin point, then another vertically upwards to the inner circle
- Dimension the three circles by clicking on them with the smart dimensioning tool, entering the same dimensions as above
- Right-click on the inner circle (100mm) and select the option to make reference geometry
- Define angle between centre lines by clicking on the horizontal one, then the one at an angle and enter 45 degrees
This will create a defined sketch, you then play around with the dimensions and see how the sketch adapts depending on what you change.
Hopefully, this has shown you how to use dimension in SolidWork, next post will look at relations and how they can be used in conjunction with dimensions.