Post 3: Design Process
I’d like to preface this by offering my thanks to the efforts of Jeffw773 and Surasia as well as countless others within the Halo Archive community. Their efforts in the creation and collection of excellent tools that let you examine the in-game characters and play dress up dollies with the spacemens has been astoundingly useful. Having these tools that allow for an easy reference that isn’t just recording fly arounds in multiplayer makes for the individual parts designing that much easier. It also limits the stretching and deformation as well as clipping of the body that happens in game.
This post is one part an analysis of my thought process for approaching any CAD project as well as a short sample on how to step through using Fusion360 for a printable design.
To address probably one of the biggest questions on why Fusion360, the collection of features makes sense for my workflow as a small business. It does many things for the Autodesk price of one thing. It does not do everything (arguably even one thing) perfectly but the ability to do multiple design workflows, produce drawings, BOMs, CAM instructions, produce renders, make animations, make flat pattens for objects, order hardware, etc., etc. all within one software package makes it something that is invaluable. Yes, I do have a paid subscription for some of the improved features but the free version for makers and education is more than capable to do more than 95% of tasks that I do, just with a few less creature comforts. I’ve had no formal training in Fusion specifically but through learning AutoCAD in highschool, SolidWorks in university and a handful of other tools in my professional and hobby career, this generic workflow process will help you think through nearly any physical object that you would like to create. Since we are talking about creating armour for real world production, this process is more focussed on the design steps to making a manufacturable item as opposed to creating a mesh to be textured, rigged and optimised for use in games and animation. That is an entirely different level of black magic that I often do not dare to touch.
Short, snappy and segmented approaches that are easily turned into a PowerPoint presentation are always the goal since broad topics that narrow down is the best way to learn and retain information so this post within a build thread of ordered segments will cover
-Identify Symmetry
-Identify Base Shapes
-Consider Part Connection
-Consider Part Creation
-Consider Physical Forces
Identify Symmetry
A quick and simple way to save time and computer processing power is to focus in on how to reduce workload that you will physically have to do and what the computer will have to calculate. For the purpose of this post I’ll be using the Rakshasa Chest as an example workflow.
The Chestplate has a left-right symmetry in design but not in detail. Perfect, we make half and most CAD software packages have a “Mirror” tool.
The Backplate is nearly four way symmetrical with a full left-right symmetry. Using the mirror tool twice here is an option, as is rotational patterning if the software allows for it. Create a base shape, rotate for four copies and edit for specifics after, amazing!
Identify Base Shapes
Any object can be broken down visually into a few base features which have complexity and detail added on later. Many CAD software packages have the ability to create base shapes such as spheres, cylinders, cubes and prisms as base features that are simple to modify. In Fusion360 there is multiple approaches to how you can interact with these features depending on your preference of Workspace.
The Form environment allows for node editing of a TSpline body.
The Solid environment allows for parametric editing of a BRep.
The Surface environment allows for patching, stitching and boundary editing of a zero thickness surface body.
As I’ve said, Fusion360 is a “Swiss Army Knife” approach that takes multiple facets of design and jams them into one. Form is closest to Blender. Solid is closest to SolidWorks. Surface is closest to SketchUp. All of them can produce the same output but dang if the inputs aren’t WILDLY different to get there.
Each of the environments ultimately can be used exclusively but mastering the ability to identify which to start in to simplify load on your computer and the overall number of steps is an art form. Sometimes you can get away with purely one environment. I’d always recommend blending as many approaches as possible but for very complex forms I’ll often find myself working in the Form environment, converting to something workable within the Solid environment and cleaning up anything that’s odd or needs refinement within Surface.
The Base Shapes for the Chestplate are best described as a rectangular prism with draft angles applied on outer faces and a hollow inner and lower face. The Abdominal Plate is an arc of a truncated cone with offset faces. The Backplate is an octagonal prism with four D Rings that connect. Nearly all parts can be prepared within the Solid Environment but for finer control you may want to dip in and out of the Form Environment for the Abdominal Plate or Strapping.
Due to the fact that this is a LONG wall of text, have a funny video showing how to edit in the Form environment of Fusion. Some people are scared of Purple Fusion but it is extremely powerful and I highly recommend you play around and learn some of the features.
Consider Part Connection
This comes from a person that spends a concerning amount of time working on machines designed by British engineers that have clearly spent a lot of time making bets at the pub about the minimum amount of access required to repair a part. I like being able to easily step by step put one thing on top of the other and not have to contort my body to do so. The goal for creating armour should be the ability to add even the most detailed parts onto a base feature in a simple manner and have a way to access that later if required for repairs. If need be, individual parts should be able to be removed, replaced and refreshed if they take damage. Greeblies should have keyed geometry to help with mounting and any interconnecting parts should have proper tolerances for the mediums that we’re working with.
All parts have inset and recessed surfaces protecting the majority of the greeblie components. NICE
Consider Part Creation
Any objection designed will have to be translated into a physical item that is manufactured by one method or another. We’re primarily focusing on 3D printing of objects due to the commonality of printing armour parts but digital design is not limited solely to FDM processes.
When focusing on an FDM part, you need to consider how it will be printed. Having a nice flat base for it sit on the print bed is always a good idea. Having faces that join with other parts being oriented for printing with the mating faces on the print bed will often result in easier joins and post processing since it’s often harder to warp a print surface than it is to have a slight misalignment or drift over the production of a long print.
Minimizing support material on external visible faces or critical mechanical structures is a balance that must be found. Clearing off grids, trees and extra remnants on large flat external surfaces is often easier than prising them out of important keying details. Oftentimes nobody will be able to see the inside of armour or its going to have additional overlapping features that make it unimportant so having minimal clean-up on the inside of armour for stray material is usually the choice I make. Having no supports required would be the ultimate dream but in the world of armour and props it’s not always achievable so compromises have to be made.
Part orientation during printing also should help with the overall strength and durability of the piece. As an example I always use, blades and long narrow objects are not the best for FDM processes. As you get closer and closer to the tip the amount of material becomes less and less with fewer options to rely on internal support materials. A blade tip on a print that was made vertically in one piece can easily have a shear due to the nature of the layered material allowing for a split along a layer line. Rotate the preparation into a horizontal print and complete it in two mirrored halves and you end up with a part that is less likely to shear and will have a bit of inherent flex of the material.
The Chestplate can be printed with the top surface facing the print surface to reduce material use and preserve internal mounting features. The Abdominal Plate can be printed using the lap joint to the Chestplate as a flat printing surface creating an upright print. All Backplate parts can be prepared flat due to their design and all detail being oriented outward.
Consider Physical Forces
Plan ahead for how parts will be interacted with in the real world. Parts like the Backplate are lightweight, float as a decorative piece on the back and overall won’t be pulled or pushed on in any major way so as long as the geometry interlocks together for proper appearance and easier glueing, no extra considerations really need to be made.
For the Chestplate we need to look at how all the external possible attachments interact with it, how high friction and mobility areas (near underarms, abdominals) will be impacted by common movements. Traditional armour relies on thin sections to be supported by ribs, splines and rolled edges to create stong plates that are lightweight and offer strengthening features that also deflect possible harm. We as modern cosplay armourers like composites and can use similar techniques on already lighter materials.
Adding recesses with the Shell feature creates an analogue of the rolled edges to help limit unwanted bending and flexing.
Adding ribs with the Rib and Web features helps add internal structures perfect for limiting unwanted bending as well as keying features for mould making.
Pair these with the ability to add internal and external shells of resin and fibreglass and you can have an extremely durable part for a fraction of the weight and machine time.
Sometimes rigid isn’t always the right answer for a part. Flexible materials or even separable plates on a floating connection that slide out of place to allow movement are the best choice.
Luckily with the Rakshasa Chest major components are separated by wide gaps and held together with strapping. If I was to rebuild any single part after attempting the Jack-O pose in this gear it would be to prepare the Abdominal Plate in a flexible to stop the initial jab of the plate when folding myself in half. Hinges for strapping helped in some cases for me personally but I need more wear time in the suit to confirm future points of issue.
Fusion Workflow Sample
This is by no means a step by step explanation but an overview of the goals of each segment. Working section by section and making use of Components will greatly help with the reliability and longevity of the workflow by reducing calculation load. Included below is also a replay of the Timeline for features that are captured.
-Import Reference Canvas
-Create Rectangular Prism for Chestplate in Solid Workspace
-Correct Rectangular Prism Draft angles
-Trim to correct shape with Split Body
-Create recesses for greeblie features with Split Face > Offset
-Create base feature of Abdominal Plate in Form Workspace
-Correct features and smooth faces in Surface Worspace
-Create Rectangular Prism for Backplate in Solid Workspace
-Apply Draft and Split Face > Offset features as required
-Create Strapping using Sketch Sweep method in Surface Workspace
-Import McMaster-Carr components for assembly
