Milestone map
Milestone map
3 milestones
Plan the Component and Establish Drawing Standards
1 week (2–3 hrs/week)
Choose a real or designed mechanical component — a bracket, shaft, housing, linkage, or similar. Before modelling, establish the drawing standards you will follow: first-angle or third-angle projection, tolerancing convention (ISO or ASME Y14.5), and title block format. Planning standards before modelling prevents the most common technical drawing error: inconsistent projection or tolerancing that makes the drawing unmanufacturable.
Proof required
Submit your drawing plan (≥300 words): the component you selected (description and rough sketch), the drawing standards you will use (projection angle, tolerancing standard, unit system), and the title block fields you will complete.
What gets checked
- Component is specific — a named part with a function, not just 'a mechanical component'
- Drawing standard is stated for all three elements: projection, tolerancing, and units
- Title block fields are listed including drawing number, scale, material, and projection symbol
Common mistakes
- Choosing a component too simple (e.g. a plain cube) — choose something with at least two features requiring tolerancing (bore, thread, fillet, chamfer)
- Not stating which tolerancing standard you will use before starting — ISO and ASME GD&T are not interchangeable; establish the convention first
Resources
Foundationstart here
Depthgo deeper
What a verifier looks for
- Confirm the component is specific enough to require tolerancing — not a plain solid with no functional features.
- Confirm both projection angle and tolerancing standard are stated — these must be established before M2 modelling begins.
- Confirm title block fields are listed.
Create the 3D Model and Generate 2D Technical Drawings
3–4 weeks (4–5 hrs/week)
Build a fully parametric 3D model of the component in FreeCAD, Fusion 360, or equivalent free tool. Generate 2D technical drawings with at least three orthographic views (front, side, top) plus a section view or isometric view where appropriate. Add full GD&T tolerances and surface finish symbols to all functional features. The drawing must be complete enough for a machinist to manufacture the part without further questions.
Proof required
Submit your 2D technical drawing (PDF or dimensioned screenshot): ≥3 orthographic views, all functional features dimensioned, GD&T tolerances on critical features, surface finish symbols, material callout, and completed title block.
What gets checked
- Every dimension needed to manufacture the part is shown — no dimension is missing or ambiguous
- GD&T tolerances appear on ≥3 critical functional features (bore, mating surface, threaded feature, or equivalent)
- Title block is complete: drawing number, title, material, scale, projection symbol, and revision
Common mistakes
- Dimensioning the model geometry rather than the manufactured intent — tolerances must reflect the functional requirement, not just the nominal design
- Omitting the section view for internal features — any internal bore, cavity, or hole detail must be shown in section
Resources
Foundationstart here
Depthgo deeper
What a verifier looks for
- Confirm ≥3 orthographic views are present and correctly projected (consistent first-angle or third-angle throughout).
- Confirm all dimensions needed for manufacture are present — ask 'could a machinist make this without calling the designer?' as the test.
- Confirm GD&T tolerances appear on ≥3 critical features with correct symbols and datum references.
- Confirm section view is used for any internal features.
Review the Drawing Against Manufacturability
1–2 weeks (2–3 hrs/week)
Review the completed drawing against a manufacturability checklist: can all features be machined with standard tooling? Are tolerances achievable with standard manufacturing processes (±0.1mm is typical CNC, ±0.025mm is precision grinding)? Are there any geometric features that create tool access problems? Write a short design review report (500–800 words) documenting any changes made and why. Have the drawing reviewed by someone with mechanical engineering or manufacturing experience.
Proof required
Submit your final drawing set and design review report (500–800 words): the manufacturability issues you identified, the changes you made (or why no changes were needed), and the review record documenting the reviewer's name, role, and challenge questions with your responses.
What gets checked
- Review report identifies at least one specific manufacturability consideration — not a statement that 'the design is fine'
- Tolerance values are calibrated to a manufacturing process (CNC, grinding, casting) — not tighter than the stated process can achieve
- Reviewer has mechanical engineering or manufacturing experience — peer review without domain expertise does not count
Common mistakes
- Skipping the manufacturability review — a drawing that looks correct in CAD may have features impossible to machine (undercuts, deep pockets with no tool relief)
- Tolerances tighter than the named manufacturing process — stating ±0.001mm tolerance on a part 'to be CNC milled' is not achievable and must be corrected
Resources
Foundationstart here
Depthgo deeper
What a verifier looks for
- Engineering Design Triad check: M1–M3 together produce a design artifact (3D model + 2D drawing set), an analysis artifact (manufacturability assessment and tolerance calibration), and a documentation artifact (design review report + review record) — confirm all three types are present.
- Confirm final drawing is dimensionally complete — every feature needed for manufacture is dimensioned.
- Confirm tolerance values are achievable by the stated manufacturing process — flag any tighter than ±0.025mm on CNC parts without explicit justification.
- Confirm reviewer has mechanical engineering or manufacturing experience.
- The Proof Accessibility Rule applies — FreeCAD (free), MIT OCW (free), MIT D-Lab resources (free), and Machinist Calculator (free) are all accessible without commercial CAD licence.
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