Contour milling with line segments in CNC Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a simple contour milling G-code segment

What is the final position of the tool after executing this G-code snippet for contour milling a rectangle?

CNC Programming

G00 X0 Y0
G01 X50 Y0 F100
G01 X50 Y30
G01 X0 Y30
G01 X0 Y0

A X50 Y30

B X0 Y0

C X50 Y0

D X0 Y30

💡 Hint

Trace the tool path step by step, noting the last move command.

The tool starts at (0,0), moves along the rectangle edges, and ends back at the start point (0,0).

🧠 Conceptual

intermediate

Understanding line segment direction in contour milling

In contour milling with line segments, why is the direction of the toolpath important?

A It controls the machine power supply

B It changes the spindle speed automatically

C It determines the coolant flow rate

D It affects the surface finish and tool wear

💡 Hint

Think about how tool movement affects cutting quality.

The direction influences chip removal, surface finish, and tool wear by controlling cutting forces.

📝 Syntax

advanced

Identify the correct G-code for a line segment in contour milling

Which G-code line correctly moves the tool in a straight line to X=100, Y=50 at feed rate 200?

A G01 X100 Y50 F200

B G00 X100 Y50 F200

C G03 X100 Y50 F200

D G02 X100 Y50 F200

💡 Hint

G01 is linear interpolation with feed rate; G00 is rapid move without feed rate.

G01 moves linearly at the specified feed rate; G00 is rapid positioning without feed rate; G02 and G03 are arcs.

🔧 Debug

advanced

Find the error in this contour milling G-code snippet

What error will occur when running this G-code? G01 X20 Y10 F150 G01 X40 Y10 G01 X40 Y20 G01 X20 Y20 G01 X20 Y10 F-100

A Syntax error due to negative feed rate

B Tool will move too fast causing damage

C No error, code runs fine

D Machine will ignore last command

💡 Hint

Feed rate must be positive in G-code.

Negative feed rates are invalid and cause syntax or runtime errors in CNC controllers.

🚀 Application

expert

Calculate total distance moved in contour milling path

Given this contour milling path with line segments: Start at (0,0) Move to (30,0) Move to (30,40) Move to (0,40) Move to (0,0) What is the total distance the tool travels?

A 120 units

B 100 units

C 140 units

D 80 units

💡 Hint

Add lengths of all four line segments.

Each horizontal segment is 30 units, vertical segments are 40 units. Total = 30+40+30+40 = 140.