3d modeling

Take steps to improve accuracy and reduce labor in 3D modeling

FIGURE 1. Although progress has been made, errors remain in product manufacturing information. For example, line 1 has an incorrect source and an OK equivalent is not acceptable.

A self-propelled shopping cart was the CAD project under discussion in the later episodes of this column. The cart’s design is still evolving electromechanically, but the basic structure and assembly have met preliminary approval from our imaginary elves.

Even while the final details are being worked out, we are adding official part numbers, descriptions, sources, and related product manufacturing information (PMI) to the modeled items. This is in support of creating the 2D drawings for manufacturing, quality control and illustrated manuals. That is, the PMI is used in many places. An accurate PMI is of paramount importance. Well-designed data entry forms contribute to speed and accuracy in this business.

Data entry progress is shown in Figure 1. This table, a bill of materials (BOM), was inserted into the CAD assembly file as a convenient way to preview the status of the PMI. A similar table is likely to be inserted into a second drawing file, by the way.

With the demo CAD software, the BOM displays the PMI contained in the CAD models (i.e. components) which are, in turn, contained in the CAD assembly.

In terms of progress, we are pleased that many of the line items in the BOM table are displaying the correct part numbers and descriptions. The task at hand is to correct several data entry errors.

For example, item 1 has a correct number, A0002, and a correct description, WHEEL ASSEMBLY. The quantity is assigned by the system, and two is what we expect. Unfortunately, the source shows incorrect data. In addition, an equivalent item should not be allowed.

Correct equivalent

As a side note to explain this specific PMI bit, Equivalent OK set to Yes allows purchases to choose the supplier and their part number. Defining the limits of equivalence is a matter of rational opinion.

In this case, the line item must be created in a specific way. There is no discretion as to where this comes from. Thus, a resounding no to the equivalents! OK. Calm.

As part of correcting data entry errors, the Custom Properties drop-down pane displays the PMI in the WHEEL ASSEMBLY (see Figure 2A). Well, maybe you don’t see Figure 2A. The displayed data entry form is incorrect and outdated. A checkbox is missing to answer the Equivalent OK question.

It was a demonstration of how early CAD projects cause slaps. In this case, a Custom Properties form was adapted from project A and the schedule table template was borrowed from project B.

This data entry form is incorrect.

FIGURE 2A. To correct the PMI, you can use a data entry form. In this example, the data entry form is incorrect and needs to be fixed before the data entry can be completed. There is a missing checkbox for Equivalent OK (Yes or No) in the form.

To synchronize the table with the form, modify the BOM table (and its template) to not display the value of the Equivalent OK property in a column or modify the form to include the missing property.

Changing the design of a data entry form

Property Tab Builder is the tool to use to update the data entry form. To use this tool effectively, you need the exact spelling and case of the property name used by the BOM table.

Figure 2B shows a way to find out the name of the property expected by the BOM table. Select the column in the table. In this example, the column titled Equivalent OK. Select Column Properties from the pop-up menu and the pop-up dialog shown in Figure 2B will appear. These column parameters are editable. The intention for now is to just remember (CTRL-C) the name of the displayed property.

Property Tab Builder creates unique forms used on assemblies, parts, and drawings (.asmprp, .prtprp, and .drwprp, respectively). Figure 2C is a screenshot of Property Tab Builder with the FMA.asmprp file open.

The Property Tab Builder user interface presents the form being edited in the center column of three columns on the screen. The column on the left of the form contains templates of things that can be used to design a form (drag onto the form). The right column displays the parameters of the element selected in the form (middle column).

In Figure 2C, a checkbox has been dragged by the mouse onto the form. With this new checkbox selected on the form, its settings have changed (shown to the right).

The checkbox caption has been set to Equivalent OK. The result is visible on the form; Equivalent OK appears next to the green tick. The spelling and capitalization of the caption are not critical. This is just to help the user of the form.

The name was also set to Equivalent OK. The spelling and case must exactly match the column property setting of the BOM table.

The remaining settings for the checkbox are a matter of preference. Our design intent is that checked means “yes, equivalent is allowed”.

On the form, checked by default eliminates mouse clicks for the form user since most elements allow discretion. If you disagree, design your checkbox to be unchecked by default.

To fix the form, we need to know what the BOM table is looking for.

FIGURE 2B. To fix the form, we need to know what the BOM table is looking for. The column properties reveal the name of the custom property it displays. In this example, the name is “Equivalent OK”. (Capital letters count.)

For this demonstration of improving the design of a custom property form, the allowed answers are “yes” and “no”. “Of course” and “never” could work just as well. It’s your form, after all. The spelling and capitalization of these answers to the Equivalent OK question will appear in the nomenclature tables and can be used by other software. So design with intention.

By default, the Configurations button in Property Tab Builder makes the property configuration specific. If the configurations are not used or not needed, do not use the configuration-specific button. In this example, we want Equivalent OK to apply to all configurations; thus, the left button is clicked as shown. Save the job. Perhaps test the form with an assembly before proceeding to design the next form.

In this example project, the OK equivalent applies to both assemblies and parts. As was done with the form for assemblies, use Property Tab Builder to open and modify the form for parts, in this example, FMA.prtprp. A screenshot and procedure for adding and modifying a checkbox to the form for parts is almost identical to that used to add the checkbox to the form for assemblies.

Here’s a CAD tip: The form for drawings—FMA.drwprp—does not imply Equivalent OK, so the work with Property Tab Builder is done for now. Make a habit of going through all three forms when updating the data entry/custom property schema.

In 2D picture, the form for assemblies is being tested. Compared to Figure 2A, we see that the radio button for component type now displays “Assembled in-house” instead of “Our design”. Also, the Equivalent OK checkbox now appears and it is unchecked because there is no equivalent wheel assembly.

When the data entry form works correctly, the top-level assembly with the BOM table is opened for review (see picture 3). Line item 1 now displays correctly. We claim that the Source is FMA. There is no vendor part number so white is fine. There is no equivalent, so No is fine. Articles 14 and 17 also look good.

The chore now is to open each of the remaining components in the BOM table, review and edit the PMI, save, close, and return to the BOM table.