Exercises: Technical documentation and budget

Explain what standardisation in technical drawing is and give two reasons why a drawing must follow standards (who will read it and what would happen if everyone drew "in their own way").

Standard paper sizes are DIN A4, A3, A2... Explain the size relationship between them (how many A4s fit into an A3) and why large drawings are folded down to A4 size for filing.

What is the title block of a drawing and where is it placed? Name at least four pieces of information it must contain (title, scale, author, date...).

Distinguish between an assembly drawing and a detail drawing: what each one shows and what each is used for during manufacturing.

What is a parts list for a project and what minimum columns should it have (quantity, part name, material, dimensions)? Give an example of a row for a shelving unit.

Explain what the budget for a project is and how it differs from the parts list: what does the budget add?

Explain what a specification document is and who writes it: what type of requirements does it set for whoever is executing the work (materials, deadlines, quality)?

A drawing shows "scale 1:10". Explain what this means and state what "10:1" would mean, giving an example of an appropriate object for each scale.

The figure shows a standardised drawing with its title block, in which a piece of information marked with ? is missing. State which piece of information it is, why it is essential in that drawing and what problem the workshop would face if it were missing.

A part measures 6 cm on a drawing drawn to a scale of 1:5. Calculate its real measurement and, conversely, state what length a real part of 2 m would have on the drawing at that same scale.

Draft the parts list for this project: a wooden table with a pine tabletop measuring $80 \cdot 50\ \text{cm}$, four 70 cm legs, twelve $4 \cdot 40\ \text{mm}$ screws and PVA glue. Use the columns: quantity, part or material, dimensions and notes.

Calculate the budget for a small carpentry project: $2{,}5\ \text{m}^2$ of pine board at $12\ \text{€}$ per $\text{m}^2$, 20 screws at $0{,}10\ \text{€}$ each and $0{,}5\ \text{l}$ of varnish at $16\ \text{€}$ per litre. Give the cost of each item and the total.

To document a piece of workshop furniture, your team is torn between drawing on A4 or A3. Reason which format you would choose for (a) a quick sketch of an idea and (b) the final detail drawing, and justify your choice.

In a detail drawing, each part has a number and dimensions. Explain what dimensions are used for and how the part numbers on the drawing link to the parts list.

Your school contracts a company to fence the school vegetable garden. Draft four conditions that you would include in the specifications (materials, completion deadline, finish and safety) and explain what would happen if they were not written down.

Order these documents according to how they are used in a real project — specifications, budget, drawings and technical report — and explain what each contributes and who its main recipient is.

A workshop manager receives the assembly drawing in the figure to manufacture a series of brackets, but halts the work order claiming that the documentation is incomplete and inconsistent.

1. Deduce and indicate what value should replace the question mark "?" in the bill of materials, and explain why the quantity of M4 screws (part 3) listed in the table seems to contradict what is directly observed in the assembly view.

2. Justify why the operator cannot manufacture parts 1 and 2 merely by measuring with a ruler on this 1:2 scale drawing, and describe what complementary technical documents (with what specific standardized information) the workshop must demand before machining the parts.

To build a bookshelf you need 2 shelves of $100 \times 25\ \text{cm}$ and 2 sides of $80 \times 25\ \text{cm}$. The warehouse does not sell pieces cut to size, but standard commercial boards of $200 \times 60\ \text{cm}$ at $18,50\ \text{€}$ each and $120 \times 60\ \text{cm}$ at $12,00\ \text{€}$ each. The kerf width of the circular saw causes a material loss of $4\ \text{mm}$ per cut.

1. A classmate claims: "The net useful surface area of the 4 pieces is only $0,90\ \text{m}^2$; since the $200 \times 60\ \text{cm}$ board has $1,20\ \text{m}^2$, we can get all the pieces from a single large board and have leftover material". Design a dimensioned cutting layout diagram to prove whether their claim is feasible in practice or if it is geometrically impossible.

2. Determine the most economical purchasing option among the viable combinations of commercial boards, adding $8,00\ \text{€}$ for screws and hardware, and calculate the actual waste percentage (unused wood relative to wood purchased).

A machine shop receives a drawing containing only a rectangular view with a dashed circle drawn inside it, without a title block, without scale, and without dimensions. Two operators argue about how to interpret it: operator A claims that it is a prismatic plate with an internal blind hole; operator B argues that it could be a stepped cylindrical shaft with a conical internal hollow.

1. Justify why the provided view is insufficient and ambiguous, and demonstrate through the drafting or precise description of two different standardized orthographic projections how two three-dimensionally incompatible parts can produce exactly that same view.

2. Design the complete standardized technical proposal that should accompany the part: which minimum views according to the first-angle projection system (European) are mandatory, which three types of functional dimensions are essential, and what legal and manufacturing data must the title block obligatorily include for the drawing to be contractually binding.

Your team has a fixed, non-extendable municipal grant of $325,00\ \text{€}$ ($21\ \%$ VAT included) to develop a weather station prototype. The initial budget estimates a material expenditure of $240,00\ \text{€}$ (tax base). The regulations of the call require adding a $10\ \%$ contingency line item on materials and, subsequently, calculating VAT on the sum of both items.

1. During assembly, a microcontroller breaks down and you must urgently replace it, generating an unforeseen expense of $35,00\ \text{€}$ before taxes. Numerically evaluate whether the reserved contingency fund covers this breakdown and calculate whether the final total cost exceeds or does not exceed the awarded grant.

2. If the cost of the remaining sensors also increases by $8\ \%$ over their initial estimate of $90,00\ \text{€}$, justify what technical or material selection decision you should make in the project so as not to exceed the financial limit without eliminating essential meteorological variables.

The following table compares the planned budget against the actual costs billed at the end of an automated sliding door project:

1. Calculate the overall percentage budget overrun relative to the initial forecast and identify which item suffered the greatest relative overrun (as a percentage of its forecast).

2. The team claims: "The overrun is solely due to materials being expensive, not to mistakes in our work". Technically refute this claim by linking each extra cost to specific deficiencies committed during the design and manufacturing phases, and formulate two corrective measures for the documentation of the next project.

During the technical audit of a school project to automate a greenhouse, the following discrepancies are detected among the submitted documents:

• In the Project Description, it is stated that the load-bearing structure will be made of extruded aluminium alloy profiles.

• In the Assembly Drawing, the title block indicates a scale of 1:10, but the lettering of the main dimension of the columns indicates "Rigid PVC pipe $\varnothing 32\ \text{mm}$".

• In the Bill of Quantities / Budget, the corresponding item prices untreated pine wood slats at $2,80\ \text{€/m}$.

• In the Specifications, clause 4.1 requires structural materials to withstand a continuous ambient humidity of $90\ \%$ and condensation without deformation or rotting for 5 years.

• Evaluate the technical, economic, and legal consequences of starting construction in a workshop with this contradictory documentation.

• Determine which material or materials proposed in the documents violate the specifications and write a reasoned technical resolution that harmonizes the description, drawings, and budget item to meet the functional requirements.

A city council is tendering the construction of a children's playground with a maximum budget of $25.000,00\ \text{€}$ (VAT included). The Technical Specifications establish two mandatory and disqualifying clauses:

1. Play structure: autoclave-treated wood class 4 or AISI 304 stainless steel.

2. Impact-absorbing surfacing: in-situ continuous rubber flooring with a minimum thickness of $45\ \text{mm}$ certified under EN 1177.

Three bids are received:

• Company A: $19.200,00\ \text{€}$ (VAT included). Structure made of pine treated with outdoor weather-resistant varnish; $30\ \text{mm}$ precast rubber tiles.

• Company B: $24.100,00\ \text{€}$ (VAT included). Structure made of AISI 304 steel; certified $50\ \text{mm}$ in-situ continuous rubber.

• Company C: $20.000,00\ \text{€}$ tax base (the applicable VAT is $21\ \%$). Autoclave-treated wood class 4; certified $45\ \text{mm}$ in-situ continuous rubber.

• As an evaluating technician, analyse the compliance of each proposal with the specifications and determine which companies must be disqualified, justifying the exact technical or economic reason.

• A council member insists on awarding the contract to Company A because it represents a saving of almost $5.000,00\ \text{€}$. Refute their position by explaining the safety, maintenance, and civil liability risks that bypassing the tender specifications would entail.

A team of students is designing a workshop bench with a solid beech wood tabletop of $160 \times 70\ \text{cm}$ ($35\ \text{mm}$ thick), a structural steel tube frame of $50 \times 50\ \text{mm}$ (with a total measured length of $8,40\ \text{m}$), and 4 legs with rubber levellers. In their budget draft, they submit the following notes:

“Item 1: Iron structure - 4 legs - 60 €”.

“Item 2: Top wood - 1 tabletop - 80 €”.

1. Technically critique the team's wording: explain why these lines fail to comply with the standardised structure of a budget item and what litigation or cost overrun risks they create when ordering the materials.

2. Prepare the itemised and standardised budget table (with columns: Item No., Full technical description, Unit, Measurement, Unit price, and Total amount), given that the steel tube is only supplied in full commercial bars of $6,00\ \text{m}$ at $28,00\ \text{€/bar}$, the beech board costs $75,00\ \text{€/m}^2$, and each leveller costs $2,20\ \text{€}$. Calculate the total direct cost and the total project budget with $21\ \%$ VAT.