ME 7: Engineering Drawing and CAD

Proof required

Link the public repo with the projection exercises in the NPTEL lectures and the drawing questions of 2.007 Exam 1 and its practice exams written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Each drawing states first- or third-angle projection with its symbol.
• Hidden lines and centre lines follow the standard line types.
• Answers match the 2.007 solutions, and each projection is checked by modelling the part in FreeCAD.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of the projection exercises in the NPTEL lectures and the drawing questions of 2.007 Exam 1 and its practice exams, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 7: Engineering Drawing and CAD, unit 1: Sketching and orthographic projection
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Each drawing states first- or third-angle projection with its symbol.
• Hidden lines and centre lines follow the standard line types.
• Answers match the 2.007 solutions, and each projection is checked by modelling the part in FreeCAD.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with the sectioning and dimensioning exercises in the NPTEL lectures and the drawing questions of 2.007 Exam 2 written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Every feature is dimensioned once, from a datum, with no duplicate dimensions.
• Fits name the hole and shaft tolerance classes and the resulting clearance or interference.
• Answers match the 2.007 solutions, and misses are reworked.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of the sectioning and dimensioning exercises in the NPTEL lectures and the drawing questions of 2.007 Exam 2, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 7: Engineering Drawing and CAD, unit 2: Sections, dimensions and tolerances
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Every feature is dimensioned once, from a datum, with no duplicate dimensions.
• Fits name the hole and shaft tolerance classes and the resulting clearance or interference.
• Answers match the 2.007 solutions, and misses are reworked.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with three NPTEL drawing exercises: draw each part by hand, model it as a fully constrained parametric part, then assemble the parts written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Every sketch is fully constrained (in OpenSCAD, every size is a named parameter), and changing one key dimension updates the part cleanly.
• The assembly has no interferences, checked with the CAD tool.
• TechDraw views of each part match its hand drawing (OpenSCAD parts are imported into FreeCAD for the drawing).

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of three NPTEL drawing exercises: draw each part by hand, model it as a fully constrained parametric part, then assemble the parts, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 7: Engineering Drawing and CAD, unit 3: Parametric CAD and assemblies
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Every sketch is fully constrained (in OpenSCAD, every size is a named parameter), and changing one key dimension updates the part cleanly.
• The assembly has no interferences, checked with the CAD tool.
• TechDraw views of each part match its hand drawing (OpenSCAD parts are imported into FreeCAD for the drawing).
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with the CAD files, an exported PDF drawing and the table of measured against modelled dimensions, and a README that says how to rerun it and what limits the result.

What gets checked

• The CAD file and an exported PDF drawing are in the repo, and the model rebuilds without errors.
• The drawing has three views, a section, a title block and a tolerance on every mating feature.
• A table lists each measured dimension (mean and spread) against the model, and any gap bigger than the spread is explained.

Common mistakes

• A result that nobody else can rerun from the repo.
• A table with no explanation of the gaps.

Powstik Guide

A CAD model of a real object you own (for example a shelf bracket, a hinge or a bike part) with a fully dimensioned drawing and tolerances, in a public repo.

Steps

1. Write down what you expect before you start.
2. Measure the object with a ruler or calipers (three readings per dimension). Model it as a fully constrained parametric part in FreeCAD, or in OpenSCAD and import it into FreeCAD. Make the drawing in FreeCAD TechDraw: three views, a section and an isometric, dimensioned from datums. Put a general tolerance in the title block and a tolerance or fit on every mating feature, chosen for its function. In a table, compare each model dimension with the mean of your three readings.
3. Fill the predicted-vs-measured (or hand-vs-simulated) table.
4. Explain every gap with a cause someone can check.
5. Write the README and ask someone who knows the subject to check it.

README
ME 7: Engineering Drawing and CAD — Model a real part and make its drawing
What I expected:
How to rerun it:
Predicted vs measured:
Why they differ:
Safety: hand tools and eye protection only

What gets sent back

• The drawing has no tolerances, or the model does not rebuild.
• Machine tools, welding, pressure vessels, combustion, or springs and flywheels storing dangerous energy without a trained supervisor.

Resources

What a verifier looks for

• The CAD file and an exported PDF drawing are in the repo, and the model rebuilds without errors.
• The drawing has three views, a section, a title block and a tolerance on every mating feature.
• A table lists each measured dimension (mean and spread) against the model, and any gap bigger than the spread is explained.
• Check the engineering and the numbers, not just that it exists: do the units, the hand calculation and the table agree?
• Build photos show hand tools only and eye protection worn: no machine tools, welding, pressure vessels, combustion, or springs and flywheels storing dangerous energy (unless a trained supervisor and a proper workshop are shown).

You'll sign in first, then come straight back here.