Lesson 3: Selecting Alignment Features

00:08

Before we can begin to measure our components, we need to align it.

00:12

This process positions it in space against the coordinate system of our measuring device.

00:17

The accuracy of our subsequent measurements relies on the precision of the initial alignment and so it's very important to get this right.

00:26

There is no right or wrong way to align a part, and the alignment strategy that you use will depend on the features of the component you want to measure.

00:34

The first step in creating the alignments is to analyze the part and decide which strategy will be used.

00:40

This partly comes from experience, as you attain an appreciation for which features necessary to make different strategies work.

00:48

The most commonly used strategies include PLP or Plane, Line and Points, RPS, which stands for Reference Point System, or a Free Form alignment, which tends to be used for complex composite components.

01:02

In this lesson, we'll be utilizing a PLP alignment.

01:07

Before we create the alignment, we need to set the features which will be utilized to create the alignments.

01:13

To create a PLP alignment, we need to have measured a plane, a line, and a point from our model.

01:19

We can do this either by directly measuring them or by constructing them from other measures.

01:24

For example, a line can be constructed from the center points of two circles.

01:29

When we're working from CAD, we're able to directly pick features from our model.

01:33

To do this, select the Wireframe Checker from the Home tab in the ribbon.

01:38

Now when we mouse over our CAD model, a yellow wireframe indicator will appear over the feature which has been identified.

01:46

For our PLP alignment, let's start by selecting this top face circle.

01:51

Clicking on the feature will turn our wireframe indicator red and feature information will appear in the Geometry Explorer.

01:58

Here, we can see some information about the feature we have just selected, such as the radius and the nominal coordinates, as well as the option to choose which type of feature we'd like to create.

02:09

For example, a single point circle can be used when a hole is smaller than the probe diameter.

02:14

In this case though, we want to create a probe circle, so select this option and then green tick to create the feature.

02:22

When a feature has been created, it will appear in the Sequence Tree in the order to be measured.

02:27

You'll see here that the PowerInspect has also automatically created a plane feature for our 2D circle to be projected onto.

02:36

PowerInspect has also automatically created a geometric group within the Sequence Tree in which to contain these features.

02:43

We can move back up into the Sequence Tree by pressing the "Green Arrow", and we can navigate through different groups within the Sequence Tree by using the dropdown menu on the left.

02:53

Let's rename this group "Alignment Features" to help us identify it later on.

02:58

Double click on the group in the Sequence Tree to modify it.

03:02

With that done, let's navigate back into our geometric group by using the dropdown menu.

03:08

As a reminder, we need a plane, a line, and a point to create our alignments.

03:13

We can get a point from the center of our circle and we're measuring a plane, so the final feature we need is a line.

03:19

We can probe the side of this face here, but I want to show you how to create constructed geometry.

03:24

So, let's create a constructed line from two circle centers.

03:30

To do this, create another circle feature on the top face in the same way as before.

03:35

We can then construct the line through the center points of these two circles.

03:40

To create constructed geometry, navigate to the Geometry tab in the ribbon bar.

03:44

Here we can create planes, lines, and points, as well as other features from a variety of sources.

03:51

We want to create a line from two points, so let's select the From Points option in the line section.

03:56

This will open a dialog box which controls the creation of new features.

04:00

Don't worry about most of these settings for now, we just need to specify which two points we'll be using to create our line.

04:08

As you can see, PowerInspect has automatically selected that two circles to create a line.

04:14

Give the line appropriate name and press "OK".

04:17

We are now ready to measure our alignment features.