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Session 5: CAD Leveling-Up I — Assemblies

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Session 5

CAD Leveling-Up I: Assemblies

Certified. Now What?

You're cleared on the machine. There's nothing to cut yet.

Before any toolpath, you need a model — and a cabinet isn't one part.

What You Already Know

Sketches, extrudes, single-part modeling — from freshman year OnShape.

What's New: Assemblies

A side panel, a front, a back, a control panel — each is its own part. An assembly is where you relate them to each other.

Part Studio vs. Assembly

  • Part Studio — where you model one part (or a few related parts)
  • Assembly — where you insert finished parts and position them relative to each other

Mates

A mate tells two parts how they relate — touching, aligned, at a fixed distance.

The Mate You'll Use Most: Fastened

Locks two parts rigidly together, as if welded — exactly what a screwed-together cabinet panel joint actually is.

Worked Example

Two flat panels, each modeled separately, joined at a 90° corner — the same joint a cabinet's side meets its front at.

Two Things to Remember

Model real thickness, not a guess.

Put calipers on the actual sheet and model the number you measure — not the number printed on the label. Nominal 12 mm plywood is rarely 12 mm. Corners won't meet cleanly otherwise.

Two Things to Remember

An assembly is still a design decision, not just clicking parts together.

Where two panels meet, and how, is exactly the kind of thing your Session 2 material choice was already anticipating.

Next Time

Session 6: CAD Leveling-Up II

Building a full practice assembly, and preparing flat panels for CAM.

'F' → Fullscreen

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Build

Step 1: Model Two Panels

In a Part Studio, model two simple rectangular panels at a real stock thickness. Measure a piece of the sheet stock you'll actually cut with calipers — the same skill from Unit 1, Session 6 — and model that number. If no stock is on hand, use the value your instructor gives you. Give the two panels different lengths so the corner joint is easy to check visually.

Do not model at 12 mm because the label says 12 mm. Session 6's practical is graded on exactly this, with a measured thickness that is deliberately not the nominal one, and the habit is easier to build now than to unlearn then.

Step 2: Create an Assembly

Start a new Assembly and insert both panels into it.

Step 3: Mate Them at a Corner

Using Fastened mates, position the two panels so they meet at a 90° corner — the way two sides of a box would.

Step 4: Verify the Joint

Zoom into the corner. Confirm there's no gap and no overlap where the two panels meet. If there is, check whether your modeled thickness actually matches on both parts.

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Checkpoint

Before you move on, confirm:

  • Both panels are modeled at a real, specific stock thickness — not a rounded guess
  • The corner joint has no visible gap or overlap
  • You used a Fastened mate, not just visual positioning
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Reflection

Answer these on your own. Reflections are individual, even when the rest of the session was team work.

  1. If your corner joint didn't meet cleanly on the first try, what was the actual CAD reason? If it did meet cleanly, what would you check first if it hadn't?
  2. A real cabinet has more than two panels meeting at more than one corner. Based on today, what do you expect to be harder about that?
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Submit

Submit your two-panel assembly file and your reflection.

Activity Complete