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Session 7: Toolpath Types & Profile Offset

Unit 2 — Manufacturing Foundations, Week 3

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Session 7

Toolpath Types & Profile Offset

You Have a Model. Now What?

CAM Studio takes your flat panel's shape and turns it into an actual path the router bit follows.

Three Toolpath Types

Diagram showing three toolpath types side by side: Profile (cuts along an outline), Pocket (clears an interior area with a raster pattern), and Drill (plunges straight down at a point)

Profile

Cuts along a drawn outline — the toolpath you'll use to cut a panel free from stock.

The Bit Has a Diameter

It's not a mathematical line — it's a spinning cylinder with real width.

Cut exactly on your drawn line, and the bit removes material on both sides of it.

Profile Offset

Diagram showing three profile offset options — Outside, On-Path, and Inside — with a dashed line showing the drawn boundary and a teal line showing where the bit's center actually travels for each option

Cutting a Part: Use Outside

The bit runs outside your line, so the material it removes is all waste — your part comes out full size.

Cutting a Hole: Use Inside

The bit runs inside your line, so the hole ends up exactly the size you drew — not slightly small.

This Is a Tolerance Problem

The wrong offset choice makes a perfectly modeled, in-tolerance part come out of the machine the wrong size.

Same idea as Unit 1 Session 9 — a spec on a screen doesn't guarantee a correct real part.

Two Things to Remember

Ask "am I keeping this or removing it?" before choosing an offset.

That question alone tells you Outside or Inside almost every time.

Two Things to Remember

On-Path is rarely what you actually want.

It ignores the bit's width entirely — both a cut part and a cut hole come out wrong-sized.

Next Time

Session 8: Pockets, Step-Over & Step-Down

Clearing out material instead of just cutting along a line.

'F' → Fullscreen

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Build

Step 1: Identify Toolpath Type

For each of the following, name which toolpath type (Profile, Pocket, or Drill) you'd use:

  1. Cutting a rectangular panel free from a full sheet
  2. Clearing a recessed tray area into a panel's face
  3. A mounting hole for a bolt

Step 2: Choose the Right Offset

For each scenario, decide Outside, Inside, or On-Path, and justify using the "am I keeping this or removing it?" question:

  1. Cutting your control panel's outer shape free from a sheet
  2. Cutting a joystick's mounting hole to its exact drawn size
  3. A test cut where dimensional accuracy genuinely doesn't matter

Step 3: Predict the Error

If you accidentally used Inside offset instead of Outside when cutting a part free from stock, would the part come out too big or too small? Explain using the bit-diameter idea from today.

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Checkpoint

Before you move on, confirm you can answer this out loud, in your own words:

Why does the same drawn line need a different offset depending on whether you're cutting a part out or cutting a hole into it?

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Reflection

Answer the following questions before submitting your work.

  1. Which offset choice do you think would be easiest to get backward by accident — Outside, Inside, or On-Path? Why?
  2. How is today's offset problem similar to Unit 1's tolerance work, even though the vocabulary is different?
  3. Session 8 covers pockets. Based on today, what do you expect is different about programming a pocket compared to a profile cut?
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Submit

Submit your toolpath identifications, your offset choices with justifications, your error prediction, and your reflection.

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