One forgotten drawing per project. Usually it is not more than that, and yet that single sheet accounts for the most expensive hours: the press brake standing still because only the left of two mirrored collar plates exists on paper, the subcontractor reporting that seventeen of eighteen sheet metal parts were in the package. Making a drawing while production waits for it is the most expensive drafting there is.
Gaps like that are not caused by laziness but by the lack of a system: nobody keeps track in their head of which of a hundred and forty parts need a sheet of their own. Only one thing helps: a fixed working order and a watertight final check, so a complete drawing set from Inventor is a matter of method instead of luck. In this article we build that method; for the final check we use, among other things, Get Drawings from the Thundercad toolbox.
Which drawings does a machine actually need?
Before you can check completeness, you have to know what complete means. Not every file in the assembly deserves a sheet, and not every sheet has to show everything: each reader has their own question.
| Drawing | For whom | What it must show |
|---|---|---|
| Assembly drawing | Assembly, customer | Overview, main dimensions, positions with parts list |
| Subassembly or welded group | Welding shop, pre-assembly | Weld symbols, dimensions after welding, its own sub-list |
| Manufactured part | Machinist, sheet metal worker | Full dimensioning, material, tolerances |
| Bought part with rework | Shop floor | Only the rework and the final dimension |
| Standard bought or catalogue part | Nobody | No drawing |
The line that causes the most debate is the one between bought and manufactured: a purchased shaft that gets sawn to length does need a sheet, however simple it is. Agree on that line once and write it down; after that, the doubt disappears from every following project.
Also look at the level of detail per reader. The fitter is served by the overview with positions and main dimensions; every extra dimension makes his sheet fuller, not better. The machinist wants everything: every fit, every tolerance, every thread. And the welder sits in between: he wants to see the dimensions after welding, not add them up from loose parts himself. Detailing every sheet for its own reader keeps the set small and readable at the same time.
Work from large to small
A complete set is easiest to reach in a fixed order:
- first the assembly drawing of the machine: it pins down the structure and the positions, and it is where structural mistakes surface;
- then, per build group, the drawings of subassemblies and welded groups;
- then the manufactured parts of that same build group, until the group is finished;
- only then move on to the next build group, and end with the loose ends such as bought parts with rework.
The order matters because changes trickle downwards. Draw the parts first, and every clash you later discover on the overview sends you back to sheets you thought were finished. Finishing group by group also prevents the most dangerous pattern: starting everywhere and finishing nowhere. And it divides naturally across people: a colleague takes the next build group and works in the same order. If you plan per order, make the build groups the lines of that planning: a group is only done when model, drawing and check are all three finished.
Where the gaps come from
Knowing where sheets go missing makes the check sharper. The five usual suspects:
- a part added to the model after the drawing round: the change made it into the model, but not into the set;
- mirrored variants: left was drawn, right seemed the same anyway, until the press brake notices the difference;
- reused parts whose drawing belongs to an old project or shows an old revision;
- a bought part that gradually became a manufactured part without ever getting a sheet;
- multi-sheet drawings where the last sheet was never finished.
What these cases have in common: they are invisible while you browse your folders. A folder full of drawings looks finished; whether it actually is finished is an entirely different question.
Ticking off which part already has a sheet is exactly the kind of counting work that gets postponed until it is too late. Leave the counting to your tools.
Try 30 days freeA watertight check: the model is the checklist
The only complete list of what is in the machine is the model itself. So check completeness against the BOM of the main assembly, never against your folder structure: the folder shows what exists, the BOM shows what should exist.
The manual route works: export the BOM, add a column "drawing present" and tick off the lines. Honest work, but it goes stale with every change, and it leans on the discipline to redo it after every revision.
With Get Drawings the same check is one action: you select the assembly and the tool fetches the drawings that belong to its parts and build groups. Whatever has no drawing stands out immediately, and you also see straight away when a sheet turns out to come from the wrong project. Run that check at two moments: when a build group should be finished, and once more just before the package leaves.
Complete is not the same as correct, by the way: every manufactured part having a sheet says nothing about what is on it. How to review the content before anything goes out the door is covered in Checking drawings before release: the complete checklist.
From complete set to package out the door
Once the set is complete and checked, the packing starts. The drawing set is the core, but rarely the whole story: work preparation wants PDFs, the sheet metal shop wants DXF files, purchasing wants the BOM. What belongs in that package and who gets which part of it is covered in The complete production package: what do you deliver, and to whom?.
For the conversion itself you no longer export drawing by drawing: with Batch Publish you turn the complete set into PDF, DWG, DXF or STEP in one run. But that is the easy step, and that is exactly why it comes last: bulk exporting a set with gaps mainly produces an incomplete package very quickly.
Frequently asked questions
Do I make drawings of bought parts?
Only when something happens to them or has to be checked: a shaft sawn to length, a purchased cover that gets holes, an incoming inspection dimension. A standard bought part that goes to the warehouse untouched gets no sheet. Fix that line once, and nobody has to think about it per project.
In which order do I process a mid-project change?
In the same order as the first round: first the model and the assembly drawing, then the affected build groups, then the parts. Finish with a fresh completeness check, because changes are exactly where gaps are born: a newly added part has no sheet yet, and nobody thinks of it.
How do I quickly see which manufactured parts have no drawing yet?
Select the assembly and let Get Drawings fetch the associated drawings: parts without a sheet stand out immediately. You can run that check on your own projects during the free trial month of Thundercad.