Scaling a model to 5% reduces more than its outside dimensions. Walls, lettering, relief, slots and connections also become twenty times smaller. Calculate the scale first, then inspect details separately.
Download the English project worksheet. Open it as UTF-8 CSV, replace the guide context with your project inputs and record observations separately from acceptance decisions. Blank cells do not indicate a passed check.
Confirm the source size and scale notation
Use one reliable real-world or drawing measurement with units. At 1:20, one unit in the model represents twenty in the original; the factor is 1 ÷ 20 = 0.05. Check whether the source is already scaled. A “1:20” filename does not prove the geometry.
Calculate and re-measure the scale
The synthetic example is an unbranded cabinet measuring 1,200 × 800 × 400 mm. At 1:20 it becomes 60 × 40 × 20 mm. Re-measure after import. A width of 6 or 600 mm indicates a likely scale or unit problem that must be resolved before production.
For buildings, continue with architectural-model preparation. For small display objects, define fragile details and viewing conditions before selecting a process.
Inventory the smallest important features
| Feature | Original | At 1:20 | Decision before a trial |
|---|---|---|---|
| Outer wall | 40 mm | 2.0 mm | Assess for the chosen process |
| Door groove | 10 mm | 0.5 mm | Test visibility |
| Letter height | 60 mm | 3.0 mm | Make a readability sample |
| Knob | 20 mm | 1.0 mm | Simplify or enlarge if needed |
These are calculations, not process limits. Material, orientation, printing method and viewing distance affect usefulness.
Make deliberate exceptions to uniform scale
Not every feature has to remain mathematically exact. Remove invisible internal geometry, combine surfaces or enlarge essential relief when recognition takes priority. Record each intentional departure from scale. Technical printability is separate from permission to reproduce or sell the design.
Identify fragile details before choosing the process
Inspect unsupported pins, thin edges, small holes and narrow gaps. Supports and orientation affect handling and finish. Do not treat one supplier's size limit as universal. If a crucial feature is below the confirmed process capability, choose a larger scale, a different representation or a representative trial.
Keep a revision record that explains each choice
Record source dimension, scale, factor, calculated final size, smallest wall and relief before and after scaling, and the chosen adjustment. Save a measurement of the reimported file with a screenshot. Proceed only when final dimensions are correct, every essential detail has a decision and remaining uncertainties have explicit trial questions. Unknown units, scale or essential detail are reasons to stop.
Request the checked model or a targeted redesign
When the dimensions and selected details are ready, send the revision, scale and visible face to the printing service. Identify the feature that needs testing, such as small lettering.
If knobs need enlarging, walls thickening or hidden geometry removing, request a targeted model change with the detail table. State where recognisability may take priority over exact scale. Uniform scaling cannot make those individual decisions for you.