Video Transcript
This QCAD tutorial introduces some basic dimensioning tools.
Example drawing: screw_m18.dxf
We will use the tools for horizontal and vertical dimensions and learn how to adjust the dimension label.
We can access the dimension tools through the CAD toolbar at the left by clicking on the button with the dimension icon.
The most common dimensions are horizontal and vertical dimensions.
They indicate the horizontal or vertical distance between two points in the drawing.
In this example, we can dimension the nominal length of the screw with a horizontal dimension.
We create all dimensions on a separate layer to easily control their appearance.
Here, we use the layer "Dimensions" for all our dimension entities.
We click two reference points to dimension the distance between them.
Then we click the position of the dimension line.
We click the right mouse button to terminate the tool.
Note that such a dimension is not meant as a means to measure distances in the drawing.
Dimensions are added to a drawing as information for the viewer of the drawing, so that the drawing provides all information that is needed to manufacture a part.
Dimensions provide precise and often more detailed information than the geometry of the drawing itself.
For example, knowing the diameter of the screw would not be enough information for it to be manufactured.
We have to also indicate what kind of thread the screw has.
In this case, it's a metric thread with a nominal diameter of 18 Millimeters, called "M18".
We use the vertical dimension tool to dimension the diameter.
Just like before, we click two reference points.
Before we click the position of the dimension line, we want to add the letter M before the number 18 to indicate that the screw has a metrical thread.
We can change the label of the dimension in the options toolbar at the top.
If we enter an M for the label, we can see that the dimension label is changed accordingly.
We could simply enter "M18" in the label field.
While this works, it is not ideal.
The dimension will now always show "M18", even if the actual measurement changes.
Instead, we enter a capital "M", a smaller than sign and a greater than sign.
The combination of smaller than and greater than signs is automatically replaced with the actual measurement of the dimension.
This is an easy way to add any text before or after the measured value of the dimension label.
We now click the position of the dimension line to add the dimension.
We add another dimension for the height of the screw's head.
If we cannot see our dimension labels or they are displayed too large or too small, we can adjust the label size in the drawing preferences.
We make sure to keep proportions, so that the various distances are in proportion to the text label size.
Now, we can adjust the dimension label text height.
In this example, we change the text height to 6.
Note how the label of one of our dimensions was moved to the side because it no longer fits between the arrows.
QCAD automatically positions the dimension labels at the center of the dimension line or to the side if the text does not fit.
Sometimes, it can be desirable to move the label of a dimension to a different location.
In this drawing, we want to move the text label of the dimension for the screw head.
To move the dimension label, we first select the dimension.
We can then move the reference point at the center of the text label using drag and drop.
We use free positioning to place the dimension label at its new location.
You should now be able to create horizontal and vertical dimensions and know how to use a different text for the dimension label.
Be sure to practice this with your own installation.
Thank you for watching this QCAD tutorial.