We will be doing a simple hole to hole dimension to demonstrate the setups to find a dimension and enter the tolerances and create nominal information from a CAD file.
- Establish your alignment based on your datum features. Be sure to do an Alignment>CAD=Part after you have set up your Construct>Coordinate System. This is a must to get the CAD model matched up to the part to be measured.
- Measure your features; in this case we will measure 2 holes as circles. Go to Measure>Circle. Choose a previously measured feature from your pull down menu or choose define and measure your plane before the circles. See Figure 1.
- If you want to do a true CAD to Part inspection where your results come up for each circle it should match the measured feature to the corresponding Nominal (CAD) feature. Then all you need to do is go to the Tolerances Tab. You will enter in the X, Y, Z, & Length tolerances you have for that feature. If you don’t want one or more of them reported then you just uncheck the corresponding box to the Left of the Tolerance Field, a checkmark in the field means it will be reported. If all your features to follow will have the same tolerances click your Save to Preferences button, by doing this you won’t have to type in these tolerances again. Click OK. Measure the next circle.
- This gives you a true CAD to Part inspection each feature to the CAD model and how much that feature is off from PERFECT based on the Datum features.
- Now let’s calculate the hole-to-hole style of dimension (straight line distance as well as the change in X, Y, & Z as a print would have) between our 2 circles. Since you did an alignment to datum features your XYZ values indicate the 3 components of the dimension from your print.
- First we need to create the nominal dimension. Go to Dimension>Length>Point/Point. Select First Point=N_Circle001, Select Second Point=N_Circle002. OK. If your circles are not already there you will have to go to the From Screen button (it looks like a GREEN Arrow) and then choose the corresponding CAD circles from the screen.
- Your results now pop up. You will want to give this dimension a recognizable name otherwise the default name is C_Length001. OK. This is now going to be your nominal from the CAD for your inspection.
- Go to Dimension>Length>Point/Point. Select First Point=M_Circle001, Select Second Point=M_Circle002. OK. See Figure 2.
- Your results now pop up. You will then go to the Nominal Tab on top of the results page. Select Nominal = C_Length001 (in this case). See Figure 3. Your Dimension is now automatically named C_C_Length001, you can choose to change the name to anything you like.
- Now go to the Tolerances Tab. You will enter in the X, Y, Z, & Length tolerances you have for that feature. If you don’t want one or more of them reported then you just uncheck the corresponding box to the Left of the Tolerance Field, a checkmark in the field means it will be reported. Click OK. See Figure 4.
- You can now do a report. You can choose from HTML, Excel, TXT, or SPCGraph Report. You can report the hole positions to the CAD file and the Length Dimension.
Please see the attached document for more details.
Click here to download: Dimensioning a Part with CAD Nominal Information
Keywords: dimensioning, dimensions