Module 2: CAD/CAM & Toolpath Generation Assessment Quiz

Module: U4M2 - CAD/CAM & Toolpath Generation Duration: 25 minutes Passing Score: 70% Format: Multiple choice and scenario-based

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What is the primary purpose of CAM software in the CNC workflow?

To generate toolpaths and G-code from a CAD design

To create 3D models of parts

To control the CNC machine in real-time

To monitor spindle temperature during cutting

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Explanation: CAM (Computer-Aided Manufacturing) software takes a CAD design and generates the toolpaths and G-code instructions that tell the CNC machine how to cut the part. CAD creates the design; CAM creates the cutting instructions.

What does a "profile" or "contour" toolpath do?

Cuts along the outside or inside edge of a shape to separate it from the stock

Removes all material within an enclosed area

Drills holes at specified coordinates

Engraves text on the surface of the material

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Explanation: A profile (contour) toolpath follows the outline of a shape, cutting along its perimeter. It can cut on the outside (for external profiles), inside (for internal profiles/pockets), or directly on the line.

What is "stepover" in the context of a pocket toolpath?

The distance the tool moves laterally between adjacent passes

The depth of each cutting pass

The distance the tool extends beyond the workpiece edge

The overlap between roughing and finishing passes

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Explanation: Stepover (also called radial depth of cut) is the lateral distance between adjacent parallel passes in a pocket or area clearing operation. A typical stepover is 40-60% of the tool diameter for roughing and 5-10% for finishing.

What is "stepdown" (depth of cut per pass) and why is it important?

The depth each cutting pass removes; it prevents tool overload and breakage

The total depth of the finished cut; it determines material thickness

The distance the tool steps away from the edge; it controls tolerance

The height the tool retracts between operations; it affects cycle time

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Explanation: Stepdown is the depth of material removed in each pass. Taking too much depth overloads the tool and can cause breakage, deflection, or poor finish. Typical stepdown for wood is 50-100% of tool diameter; for aluminum, 25-50%.

When cutting out a part using a profile toolpath, which side of the line should the tool cut on?

Outside the line for external profiles, inside the line for holes/pockets

Always directly on the line

Always on the left side of the line

It does not matter — the result is the same

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Explanation: Tool compensation is critical. For external profiles, the tool must cut outside the line so the finished part matches the design dimensions. For internal features (holes, pockets), the tool cuts inside the line. Cutting on the line would make external parts undersized by one tool radius on each side.

What is the purpose of "tabs" or "bridges" in a profile toolpath?

To hold the cut piece in place and prevent it from shifting or being thrown by the bit

To create decorative connections between parts

To mark the part number on the finished piece

To reduce cutting time by skipping sections

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Explanation: Tabs are small sections of uncut material that keep the workpiece attached to the surrounding stock during the final pass. Without tabs, a fully cut-out piece can shift or be thrown by the spinning bit. Tabs are typically 0.125"–0.25" wide and 0.04"–0.08" tall.

What is "climb milling" versus "conventional milling"?

Climb milling: tool moves in the same direction as the feed; Conventional: tool moves against the feed

Climb milling: cutting uphill on an incline; Conventional: cutting on a flat surface

Climb milling: using larger bits; Conventional: using smaller bits

Climb milling: high RPM; Conventional: low RPM

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Explanation: In climb milling, the cutting edge enters the material at maximum chip thickness and exits at zero — the tool rotation direction matches the feed direction. In conventional milling, the opposite occurs. Climb milling generally produces better finish but can cause grabbing on machines with backlash.

A student's CAM software shows a feed rate of 100 IPM and a spindle speed of 18,000 RPM using a 2-flute ¼" end mill. What is the chip load per tooth?

0.0028" per tooth

0.0056" per tooth

0.0014" per tooth

0.180" per tooth

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Explanation: Chip load = Feed Rate ÷ (RPM × Number of Flutes) = 100 ÷ (18,000 × 2) = 100 ÷ 36,000 = 0.00278" per tooth. This is within the typical range for a ¼" end mill in wood (0.002"–0.005").

What is a "post processor" in CAM software?

A translator that converts generic toolpath data into machine-specific G-code

A tool that smooths the surface after cutting is complete

A quality check that validates the design before cutting

A filter that removes unnecessary tool movements to save time

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Explanation: Different CNC controllers (GRBL, Mach3, LinuxCNC, Fanuc) use slightly different G-code dialects. The post processor translates the CAM software's internal toolpath representation into the specific G-code format your machine's controller expects.

What is the purpose of a "lead-in" on a profile toolpath?

To gradually engage the tool with the material to prevent marking the finished edge

To increase the spindle speed before cutting begins

To align the tool with the X-axis before the first cut

To preheat the cutting tool before it contacts the material

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Explanation: A lead-in is a curved or angled approach path that brings the tool into contact with the material gradually. This prevents the plunge mark that would occur if the tool entered directly on the profile line, resulting in a cleaner finished edge.

When should you use a roughing toolpath followed by a finishing toolpath instead of a single toolpath?

When you need high dimensional accuracy and surface finish on a complex shape

Only when cutting metals — wood never needs finishing passes

When the machine does not have enough power for a single pass

Only when the CAM software cannot generate a single toolpath

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Explanation: Roughing quickly removes bulk material with aggressive parameters, leaving a small amount (0.010"–0.030" stock-to-leave). The finishing pass then uses lighter cuts at higher speeds to achieve accurate dimensions and smooth surfaces. This two-step approach is standard for 3D contours and precision parts.

A student runs a simulation and notices the tool is cutting through a clamp. What should they do?

Modify the toolpath boundaries or move the clamps before running the job

Run the job at reduced speed so the clamp damage is minimal

Ignore it — simulations are not accurate

Remove the clamp and rely on material weight to hold the workpiece

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Explanation: CAM simulation exists specifically to catch collisions before they happen. Cutting through a clamp damages the tool, clamp, and potentially the workpiece, and creates a dangerous projectile hazard. Always resolve simulation warnings before cutting.

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Last Updated: 2026-03-19