3D Printing & Additive Manufacturing

A Kaern Schools Course — taught on cycleCAD Instructor: Addi · Discipline: Functional prototypes & end-use parts for cycleWASH machines

Welcome from Addi

Pull up a stool. My name is Addi, and for the next seven modules I'm going to teach you additive manufacturing the way we actually do it on the shop floor — not as a science fair, but as a tool that earns its keep. Everything we design here lives in cycleCAD, our browser-native B-Rep CAD with built-in slicing and DFAM tooling. And everything we print has a job: brackets, nozzles, manifolds, guards, and fixtures that go into real cycleWASH bicycle-washing machines.

A few house rules. First, we measure twice and print once — filament is cheap, but eight hours of machine time and a missed delivery are not. Second, we never confuse "it printed" with "it works." A part that survives the build plate but fails in a wet, vibrating, chemical-splashed wash bay has failed. Third, ask questions out loud. I end almost every lesson with one, and I mean it.

Let's build something that lasts.

How this course is structured. Seven modules, each with learning objectives, lessons (with the actual teaching script — what I say — plus a worked cycleCAD example and a hands-on exercise), three common mistakes I see every cohort, and a check-for-understanding. We close with a capstone and a rubric. Total seat time is roughly 28–32 hours including machine time.

| # | Module | Focus | |---|--------|-------| | 1 | AM Processes & When to Use Them | FDM, SLA, SLS — strengths, limits, selection | | 2 | Design for Additive (DFAM) | Designing for the process, not against it | | 3 | Materials & Their Properties | Polymers, mechanical/chemical behavior, selection | | 4 | Slicing, Supports & Orientation | Turning geometry into toolpaths | | 5 | Print Quality & Troubleshooting | Diagnosing and curing defects | | 6 | Post-Processing & Finishing | From raw print to finished part | | 7 | Functional/End-Use Parts, Jigs & Fixtures | Production-grade parts that ship |

Module 1 — AM Processes & When to Use Them

Learning Objectives

• Explain the working principle of the three core polymer AM processes: FDM, SLA (vat photopolymerization), and SLS (powder bed fusion).
• Compare the processes across strength, surface finish, isotropy, cost, lead time, and material range.
• Select the correct process for a given cycleWASH part using a structured decision framework.
• Describe the end-to-end AM workflow from CAD model to finished part.
• Identify where AM beats subtractive/injection molding — and where it loses.

Lesson 1.1 — The three processes, and how they actually work

Teaching script (Addi speaks):

"Let's start by demystifying the machines, because once you understand how a process lays down material, you can predict almost everything about the part it produces. Think of the three processes as three different ways of building a sandcastle. FDM — fused deposition modeling — is like piping icing: a hot nozzle squeezes molten plastic, layer on layer. It's the workhorse on our floor, cheap and forgiving, but those layers are weld lines, and welds can be weak. SLA is like developing a photograph in resin — a laser or projector cures liquid into solid, layer by layer, with gorgeous detail you can read a serial number off of. But cured resin is often brittle and hates UV. SLS is the clever one: it sinters nylon powder with a laser, and the surrounding loose powder supports the part, so you get strong, nearly isotropic, support-free geometry — at a higher price and a grainy finish.

Here's why it matters: a cycleWASH spray nozzle, a sensor mount, and a one-off assembly jig each want a different one of these. Choosing wrong wastes a day. So — before we touch geometry — which of these three do you think handles a part that needs to flex repeatedly without snapping, and why?"

Worked example — cycleCAD: Open the cycleCAD Process Comparator panel. Load the sample model hose-retainer-clip.step. cycleCAD overlays a process card for each method showing estimated cost, build time, min wall, and a layer-direction strength arrow. Note how FDM shows a red "anisotropy" flag on the snap-fit arm because the load runs across layers, while SLS shows green. This is the engine of process selection.

Hands-on exercise: In cycleCAD, import any three sample parts (nozzle-tip, panel-bracket, cable-guide). For each, open the Process Comparator and record the recommended process and the single deciding factor (detail, strength, or cost). Write one sentence per part justifying the call.

Common mistakes:

1. Choosing FDM for everything because it's the default — then being surprised when a thin snap arm shears along a layer line.
2. Picking SLA for a structural load-bearing bracket; the detail is lovely but the part is brittle.
3. Ignoring lead time — SLS often means an outsourced print and a multi-day wait.

Check for understanding:

• Which process is naturally isotropic and support-free, and why?
• Your part has 0.3 mm engraved logos and must survive outdoor UV. What's the conflict, and which process compromises least?

Lesson 1.2 — A decision framework and the full workflow

Teaching script (Addi speaks):

"Engineers love rules of thumb, so here's mine, and I want you to tattoo it on the inside of your eyelids: Form, Fit, Function, Finance. Ask in that order. Form — does it need fine detail? Then SLA's in the running. Fit — does it mate with other parts to tight tolerance? FDM and SLA hold tighter than SLS. Function — does it carry real loads, flex, or live in chemicals and heat? Now we're talking SLS nylon or engineering FDM filaments. Finance — what's the budget and the deadline? FDM wins on cost-per-part for low volume; SLS wins when you need ten strong parts overnight.

Now the workflow, because a process is just one station on the line. It goes: model in cycleCAD → check the design against the process (that's DFAM, Module 2) → orient and slice → generate supports → print → remove supports → post-process → inspect → ship or assemble. Every one of those steps can ruin the part if you rush it. The biggest beginner trap is treating slicing as an afterthought — it's where half your quality is decided.

I once watched a tech reprint a manifold four times because he never checked orientation. Forty hours of machine time for a five-minute decision. So tell me: in that four-stage framework — Form, Fit, Function, Finance — where would you place a watertight chemical manifold for our Pro Platinum?"

Worked example — cycleCAD: Use the cycleCAD DFAM Wizard on pump-manifold.step. Walk the Form-Fit-Function-Finance checklist; the wizard scores each axis 1–5 and recommends SLS for watertightness and chemical resistance, flagging FDM's layer porosity as a leak risk.

Hands-on exercise: Build a one-page decision matrix (rows: 4 cycleWASH parts; columns: Form/Fit/Function/Finance + chosen process). Defend each choice in the cycleCAD notes field attached to the model.

Common mistakes:

1. Optimizing for cost before confirming the part can even perform its function.
2. Forgetting watertightness is a function requirement, not a finish requirement.
3. Skipping the workflow's inspection step and discovering defects after assembly.

Check for understanding:

• Order the four F's and explain why Finance comes last.
• Name two workflow steps where a wrong decision is cheap to fix early but expensive to fix late.