Bills of materials and callouts
Generate the parts list from the model, so what you order matches what you designed.
By the end you can
- Generate a bill of materials from an assembly and balloon it on a drawing
- Use hole callouts instead of dimensioning every hole by hand
- Keep the parts list accurate when the design changes
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The last gap between a design and a robot is knowing what to buy and how many.
The BOM comes from the model
A bill of materials generated from the assembly is correct by construction. A hand-typed spreadsheet is correct on the day it was written.
That difference shows up in a specific, expensive way: you redesign the lift to use six bearings instead of four, you order from the old spreadsheet, and the parts arrive two short on the Thursday before a qualifier.
Name and number parts before generating
The BOM shows whatever the parts are called. Spend ten minutes naming things properly and the output is a usable order list; skip it and you get a table of Part 1 through Part 23.
Balloons connect the table to the picture
A balloon is a numbered marker pointing at a component, keyed to the BOM row. It is how someone assembling from the drawing knows which of four similar standoffs goes where.
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Generate the BOM on an assembly drawing.
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Auto-balloon the view, then drag balloons so the leaders do not cross.
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Check quantities against the real order. The BOM counts what is in the model — a discrepancy means the model is missing something, which is worth knowing now.
Hole callouts
If you used the hole feature rather than sketched circles, this is where it pays off. A hole callout reads the hole's own data and writes 4× ⌀4.2 THRU automatically — no manual dimensioning, and it updates when the hole changes.
This is the fourth time the hole feature has paid for itself
Consistency, easy global changes, automatic callouts, and now an accurate BOM. All from choosing the right tool in a lesson that seemed like a detail at the time.
Next
Everything so far has been general CAD. The last unit is entirely FTC.
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