Design and Assembly

Purpose

The first step in planning and designing an architectural model is to establish a clear understanding of the purpose of your model. While your design process is unique to you, it may be helpful to categorize reasons for modelling to establish some guidelines. Here are some examples.

Sketch Model

A sketch model is typically used to describe a conceptual or formal idea. It often made quickly and roughly as part of a working process. These models are most commonly made by hand from a single, inexpensive material such as cardboard or foam.

Process Model

A process model is more refined and dimensionally specific than a sketch model. This model is used as a tool in the design process to consider specific design decisions rather than broader concepts or forms. A process model might be of an entire project, or a single detail. Commonly these will be made from simple, workable materials, such as boxboard or balsa.

Presentation Model

As it sounds, a presentation model is a final finished model which aims to articulate your design to an audience. This model might be a scale model of a building, a 1:1 model of a detail, or a sculptural model which conveys concept or process. These models require large amounts of work and are typically crafted from high quality materials with permanence in mind.

Planning

Once you have decided on the purpose and scope of your model you can begin to plan. Planning your model is the process of making macro decisions about feasibility and desired outcome. Whether you are thinking of making a single model or a series, it's advisable to make a rough plan of basic material ideas, scale/dimensions, and intention.

Here are the key things that you may like to consider in planning you model. Decisions you make here may affect the design and accuracy of the outcome.

Time
Cost
Scale/scope

Time

Time is probably the most important consideration when planning anything. Given that you may be working to deadlines, have a good understanding of the processes and materials you want to use in your model and how those relate to the time constraints. A simple schedule will help.

Cost

Making models can be incredibly cheap or incredibly expensive. A sketch model should be as cost effective as possible, while a presentation model will most likely require cost to achieve the level of finish desired. Setting a budget can help you to design your models by opting for materials or processes which fit. Alternatively, having a budget may invite you to look at re-using or recycling materials, or perhaps using experimental materials; you could make a massing model by baking bread in the desired form, or you might use only offcuts from the recycling. These constraints can add new levels of interest to your work.

Scale & Scope

Scale refers to the size of your model. If time and cost are an issue, making a large model may not be ideal. If there is a scale that you desire to show a particular level of detail, consider making sections of the model which highlight this detail and others that are as basic as possible. Hierarchy is a powerful principle.

Scope refers to the comprehensiveness of your overall modelling project. If you want to show process or iteration, you may want to plan a series of similar models. Additionally you may want to show high levels of design detail with 1:1 models. When planning the scope of your models, remember to be concise and thoughtful about what is important. Plan to focus the attention of your audience just like you might with a drawing.

Design

When designing models, there are a number of things to be taken into account.

Materials
Methods
Detail
Display
Longevity

Display

Consider how your model is being displayed and what your intentions are around its display. A three-dimensional model is not restricted to being shown on a table. You might like to build a special plinth for a detailed model, or frame a section model and hang it on the wall.

Longevity

How robust does the model need to be? Is it operable, will it be touched? Is it delicate? Should it be protected in some way? Do you need a custom container to keep it safe?

Scaled Model Making

Scaled model making refers to the process of rationalising a 3D model in digital space and transforming it into the physical realm. By doing so, the limitations of scale, geometry and material will affect the realisation of a project. Ideally, when planning a model for the real world simplifying a digital model for digital fabrication is essential to achieve accurate and realistic parameters for a desired physical 3D model.

While choosing the best fabrication method is secondary yet equally important, material selection determines which method and what finish can be achieved.

Material Selection

Material selection is paramount in fabrication, insofar as simplifying and rationalising a model may drastically affect material choice. Both structural performance and physical appearance affect how a model comes together. To understand which material is best for your required outcomes, you have to first understand three main principles.

Materials Scaling.
Material Behaviour
Tolerances

When re-scaling and rationalising a 3D model it is important to have an idea of what material performance or aesthetic is desired.

Did you know? The Fab Lab's material stock list has a variety of different materials and is constantly updated. External materials are also welcome and must be supplied with a Material Safety Data Sheet to be assessed by a technician. Follow the link below for more information.

Scaling

Materials don't scale linearly

Materials are a defined object and therefore do not suit variable changes to scaling (smaller or larger) if thickness is not accounted for. This is given that the material can increase its thickness, i.e hardwoods, plastics...etc.

It is very difficult to predict a specific material to perform exactly how you intend without experimentation and testing. This is important to understand, as materials will not behave as intended once the original intention is altered or scaled directly.

Material behaviour

Different material properties will behave differently to one another, not just structurally but also in performance under a particular machine e.g. Luan Ply, MDF, Non-Structural Plywood, Furniture grade plywood.

This means that prototyping with similar materials intended for a final model is essential in achieving accurate performative outcomes as well as understanding its finish quality.

It is also important to understand that, in contrast with the idea that materials don't scale linearly, selecting an appropriate material that approximates a material at a 1:1 scale is important when real scale model making.

Tolerance

What is tolerance?

Tolerancing refers to the dimensional manipulation required to enable two pieces of material to fit together, similar to the way puzzle pieces fit together just so.

In physical fabrication, tolerancing is dependent on the behaviour of material and varies from material to material. For example, wood materials will swell and expand in colder environments, while constricting during hotter environments. This will ultimately affect the way objects fit together, and may result in variation over time.

If a square piece is required to fit into a square hole with the same measurements, there will need to be a small gap created between the two components to allow for the desired fit. This accounts for material variation caused by things like temperature, the cutting process or the nature of the material itself.

How to include tolerance

Best practice for tolerancing occurs once all parts have been laid out for fabrication and it can be determined what areas need to fit together. Once this has happened, parts can be altered through methods like offsetting or moving curve control points an appropriate amount. Tolerancing values are often in the vicinity of 0.1mm to 0.35mm depending on material.

It must be stressed that tolerancing plays a critical part in the completion of any project with interlocking parts. Tolerancing is not about finding the closest, 'tightest' fit between two components, it is instead about finding the desired fit. In some projects, a large tolerance (a loose fit) might be the desired result.

Both materials and methods can effect the tolerances required and often a process of trial and error is required. The table below outlines some example tolerances for CNC machining plywood.

Examples of tolerance and its function

Tolerance

Reason

Result

0.0mm

Exact

Difficult to slot parts, requires sanding.

0.2mm

Tight

Difficult to slot parts, requires force.

0.3mm

Glue Up

Tight with an allowance for glue.

0.5mm

Knock down

Loose fit for parts that need to come apart quickly/repetitively

Simplifying the Model

Now that we have rationalised the model and understood what material and which method is best to achieve our desired aesthetic/function, simplifying the 3D model will ensure a quicker and ‘cleaner’ fabrication process.

Scale

Scale in physical fabrication is vital in the overall aesthetic/function of the model. As physical models don’t scale linearly, nor will our 3D models. That is, the smaller or bigger the model gets, the materials will drastically change the performance of its physical nature based on thickness. Scale is paramount in simplifying and model to achieve a desired outcome as too small may result in loss of detail and too big may result in a costly model, depending on the machine chosen.

Depending on the material and machine, scale must be appropriate to the available material and standard sizes of the machine, as well as understanding time and cost.

Structure

As discussed in scale, the structure of a physical model does not scale linearly. Without rationalising its structural components contrasted with material selection. Too small of a scale will result in fiddly and breakable parts, while too large of a scale will be over-designed and result in increased processing time.

Simplifying the structural components by either thickening small structural parts or reducing the amount of parts will reduce time and increase efficiency.

Complexity

The complexity of a 3D model will drastically affect the viability of its translation to the physical. Rationalising will help understand its structure while the complexity of a model will often result in the selection of the appropriate machine. Complex models will require consultations with a fabrication technician and sometime result in the alteration of the design. Simplifying the complexity will reduce time and cost of processing, as well as ensuring sound fabrication. Reducing the complexity of the model is helpful when designing for the appropriate scale.

Binding agents

Binding models together can make or break the overall appeal and functionality of a model. Utilising binding agents as not just functional but also aesthetic components within model making amplifies the overall appeal.

Tape

Tape can be used as a quick and easy method to stick sketch models together. Quick articulation of ideas may be achieved, with minimal time spent on the construction. However tape can be very distracting in a final presentation.

Glue

Glue as a binding agent is the most commonly utilised binding agent in model making methods. It provides effective binding whilst providing quality finishes. It is important to understand that different types of glues are appropriate for different types of materials, such as wood glues for various wood types e.g. plywood, hardwood, MDF, or BSI/UHU Adhesive glue for acrylics and plastics as it fuses plastic at a quicker rate.

Nuts and Bolts

Screws, nuts and bolts and more technical binding agents that provide a professional and intricate detailing aesthetic/functionality.

Post-Processing

With a smallest amount of consideration to finishing processes, the quality of all models may be improved dramatically, prior or post assembly.

Often the fabrication process can leave unwanted marks or material in undesirable places e.g burn marks from laser cutters and CNC bits along with ridges left by the CNC machine. The designer should strive to understand this and adequately allot time for remediation.

Laser Cutting

Laser cutting is a digital fabrication process that leaves burn and scorch marks on most materials due to the heat of the laser during operations.

The effects of this are most apparent on material such as MDF or plywood. Extensive sanding can be required to remove the marks left by the laser beam, otherwise an alternative would be to outsource material. Externally-sourced poplar plywood is a great material to laser cut as the scorch marks are generally less intense than the cheaper Luan plywood stocked at Fablab.

Did you know? If scorch marks will be a large issue on your project, please consult Fab Lab about having our settings tailored to leave as little scorch marks on your work as possible. This can sometimes be a long process of trial and error which will be added to the price to your job.

Painting pieces that have been laser cut can be a quicker way to hide any unintended marks left by the fabrication process. The spray booth in Fab Lab is perfect for this task as it extracts any fumes created.

Use this link for a step-by-step process for how to remove scorch marks from your laser project

CNC Milling

Most CNC models will require slight-to-moderate sanding post operation, even when a student specifies a fine finish. This can be done by hand or with an orbital sander in the Machine Workshop using a combination of 180 and 240 grit sandpaper.

The quality of timber and plywood models can be increased by applying an oil or wax finish after sanding.

Use the link below to be redirected to the MSD Workshop page to read up on types of finishes, what finish would be best for your project and how to apply your chosen finish correctly.