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Session 9: Apply CAM to a Practice Piece

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Session 9

Apply CAM to a Practice Piece

Two Sessions of Vocabulary

Profile, offset, pocket, step-over, step-down, tabs.

Today, all of it, programmed for real — on one small shape, not the real project yet.

Meet the Test Coupon

A small practice shape that includes a bit of everything: an outer boundary, an interior pocket, and a hole.

An isometric view of the test coupon: a flat rectangular plate with a shallow rectangular pocket on the left of its top face and a single round hole through it on the right

Meet the Test Coupon

A real, standard manufacturing practice — verify your setup on something small and cheap before committing to the real part.

Today's Job Has Three Toolpaths

  1. Profile — cut the outer boundary free (Outside offset)
  2. Pocket — clear the interior recess (step-over set)
  3. Drill — the hole
The coupon with all three toolpaths displayed at once: concentric blue passes filling the pocket, a single plunge down into the hole, and blue passes tracking around the outside of the plate at several depths

Order Matters

Cut the pocket and drill the hole before the profile cut frees the part — not after.

Order Matters

Once the profile cut separates the part (tabs aside), it's far less securely held for any further operation.

Simulate Before You Trust It

Run the simulation and actually look at it — check that all three operations ran, in the order you intended, without the toolpaths colliding with each other.

Two Things to Remember

Sequence is part of the program, not an afterthought.

Which operation runs first can matter as much as getting each individual one right.

Two Things to Remember

A simulation that looks right still needs a human check.

Don't just glance at it — confirm each toolpath did what you actually intended.

Next Time

Session 10: Post-Processing & Troubleshooting

Turning this simulated job into real code your machine can run — and catching mistakes before they cost material.

'F' → Fullscreen

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Build

Step 1: Get the Part Into Fusion

Export the test coupon from OnShape as a STEP file, then open it in Fusion. Remember from Session 7: the shape crosses over, the design history does not.

Step 2: Create the Setup

Switch to the Manufacture workspace, then create a new Setup. Three things to get right before you program anything:

The Fusion Manufacture workspace, with the MILLING tab showing SETUP, 2D, 3D, DRILLING and ACTIONS groups in the ribbon, and a browser tree on the left containing CAM Root, Models and Setups

If your ribbon doesn't look like this, you are in the wrong workspace. The tab row reads MILLING, TURNING, ADDITIVE — not SOLID, SURFACE, MESH. That is the fastest way to tell, and switching workspaces is the step people skip.

  • Operation type — Milling
  • Work Coordinate System — put the origin somewhere you can actually find on the real stock. A corner of the material is far easier to zero to than the middle of a curve.
  • Stock — set it to your real material thickness, not a guess. Everything Session 8 taught about step-down is measured against this number.
The Fusion Setup dialog open beside the coupon, showing Operation Type set to Milling, a Work Coordinate System group with Orientation, Origin and Stock Point, and a Model set to Body — with the WCS arrows drawn on the part and the stock shown as a translucent box with corner grips

Watch the model, not just the dialog. The colored arrows are your WCS origin and the translucent box with grips at its corners is your stock. If the arrows are sitting somewhere you could never touch with a wrench on the real machine, fix it now — that is the origin you will be zeroing to in Session 13.

Step 3: Program the Pocket

Add a 2D Pocket operation for the interior recess. Select the pocket face, then open the Passes tab and set your Stepover, tick Multiple Depths, and set Maximum Roughing Stepdown. Be ready to justify both numbers — defaults left unexamined are not an answer.

The coupon's pocket filled with concentric blue cutting passes that spiral inward, with a green lead-in and a helical entry ramp near the center

Your pass count will not match this picture, and it should not. This one was programmed with a 6.35 mm (1/4 inch) bit at a 40% step-over. Change either number and the spacing of those blue passes changes with it — which is the whole reason you have to justify your own.

Step 4: Program the Drill

Add a Drill operation and select the hole. First, do the check from Session 7: is this hole the same diameter as your bit? The coupon's hole is sized so that it is — which is exactly why a Drill works here. If it weren't, this would have to be a pocket instead.

The coupon with the drill toolpath shown: a single vertical line plunging straight down into the hole, with no lateral movement at all

Notice how little there is to look at. A drill toolpath is one plunge and one retract — no passes, no step-over, no step-down. That sparseness is the tell: if your hole needed a spiral in it, you picked the wrong operation.

Step 5: Program the Profile, With Tabs

Add a 2D Contour operation for the outer boundary. On the Geometry tab, confirm the red offset arrow points outside the line — that is Session 7's offset decision, made visible — and tick Tabs so the part doesn't come loose mid-cut.

Confirm this operation is sequenced after the pocket and drill in the browser tree. Order is the whole point of today.

The coupon with the profile toolpath shown: blue passes tracking around the outside of the plate at four descending depths, with small raised notches interrupting the lowest passes where the tabs are

The tabs are visible in the toolpath, not just in the dialog. Look at the lowest passes: they step up and back down in several places instead of running level. Each of those steps is a sliver of material left uncut, holding the part in the sheet until you cut it out by hand. If you tick Tabs and see no steps, the tabs did not take.

Step 6: Simulate and Check

Right-click your Setup and choose Simulate. Turn on Stock so you can watch material actually disappear, then play it start to finish. Confirm all three operations ran, in the right order, with no collisions or unexpected gouges.

Fusion in simulation mode, with a SIMULATION ribbon, the tool and its holder rendered above the coupon mid-cut, playback controls with a scrub bar along the bottom, and a SIMULATE panel on the right whose Stock checkbox is unchecked

Look at the Stock checkbox on the right of that panel — it is off. That is the default, and it is why this instruction exists. Left off, you watch a tool fly through empty space and learn nothing about material removal. Tick it, and the block stays on screen and gets carved.

Watch it, don't skip to the end. A wrong order still produces a finished-looking result — the error is only visible while it runs.

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Checkpoint

Before you move on, confirm:

  • Pocket and drill are both sequenced before the profile cut
  • Your step-over and step-down choices are ones you can justify, not defaults left unexamined
  • The simulation ran clean, and you actually watched it, not just glanced at the result
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Reflection

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

  1. Did you get the toolpath order right on your first attempt? If not, what tipped you off that something was wrong — and would you have caught it without simulating?
  2. Session 10 covers turning this simulation into real machine code. What do you think could still go wrong even after a completely clean simulation?
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Submit

Submit your Fusion file with all three toolpaths and your reflection.

Activity Complete