This blog is the last part in our “Level 2” Bill of Materials (BOM) series which focuses on BOM management.
The Level 200 topics covered:
- 201 – Equivalent Components (Merged Parts)
- 202 – Part Numbers and Stock Numbers
- 203 – BOM Rollup “Errors” (*Varies*) – This Post!
When Autodesk Inventor Bill of Materials see two or more components that are equivalent, it creates a “rollup” of the items, showing them as a single row in the BOM and in resulting Parts Lists. In this article, we will explain more about BOM rollup errors. Stay tuned for our advanced “Level 3” BOM series coming soon!
What are BOM Rollup Errors?
*Varies* cell
If the properties of the rolled-up components do not match, Inventor does not know which value to use in the Bill of Materials as the value to communicate for the resulting rollup. Since the components are supposed to be the same component, Inventor requires that the iProperties be the same.
For example, three equivalent parts have three different Description iProperties: “10-32×0.5 Hex Head”, “10/32-1/2 Hex Cap Head”, and “#10/32 Hex Cap – 0.5 in Long”. Inventor does not know which description to actually use, so they must be the same.
Setting the properties to be the same value is easy.
- Start the Bill of Materials dialog from the assembly or by right clicking on a Parts List and selecting “Bill of Materials…”
- Find the rollup row. Properties that conflict are highlighted in the BOM dialog.
- Click in the cell that says *Varies* and type in the desired value. The value will be saved to all the components in the rollup.
Quantity Rollup Errors
Quantity has a special handling with Rollups. The rules for handling quantity during a roll up that Inventor follows are:
- When two or more components are in a rollup, they must have a compatible Base Quantity:
For Example: All must be units of Length, Volume, Mass, or Each
- The units do not have to be the same (i.e., one can be inches, and another can be millimeters), as long as they are the same basic type of unit.
- When the unit types match, but the units do not, Inventor chooses the unit from the first item it encounters when creating the rollup
Inventor will warn the user if rollup errors in quantity occur before printing or publishing a drawing. To resolve these errors, change the Base Quantity of all components in the rollup to all be the same basic type (Each, Length, Volume, or Mass) as described in BOM 103.
Summary
BOM rollup errors such as *Varies* occur when two or more components with the same part number are merged by the Bill of Materials and one or more Properties do no match between the components. For standard iProperties, the user can edit the rollup and type in the value they want, and it will be saved to the components in the rollup errors. For Quantity errors, edit the Base Quantity of the components so they have compatible unit types such as Each, Length, Volume, or Mass.