Depth of cut and step-over in CNC Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Calculate total passes for depth of cut

A CNC program sets a total depth of cut of 12 mm with a depth of cut per pass of 3 mm. How many passes will the machine make to complete the cut?

A 4

B 6

C 3

D 5

💡 Hint

Divide total depth by depth per pass.

Total passes = total depth / depth per pass = 12 / 3 = 4 passes.

💻 Command Output

intermediate

Calculate step-over distance in a CNC milling operation

If the tool diameter is 10 mm and the step-over is set to 40% of the tool diameter, what is the step-over distance?

A 6 mm

B 2.5 mm

C 4 mm

D 5 mm

💡 Hint

Step-over = tool diameter × step-over percentage.

Step-over distance = 10 mm × 0.4 = 4 mm.

📝 Syntax

advanced

Identify the correct G-code for setting depth of cut

Which of the following G-code lines correctly sets a depth of cut of 5 mm in a CNC milling program?

A G01 Z5.0 F100

B G01 Z-5.0 F100

C G00 Z-5.0 F100

D G00 Z5.0 F100

💡 Hint

G01 is linear feed move; negative Z moves down.

G01 moves the tool linearly at feed rate; Z-5.0 moves down 5 mm for cutting.

🚀 Application

advanced

Calculate total machining time with depth of cut and step-over

A CNC milling operation uses a tool diameter of 8 mm, step-over of 50%, depth of cut per pass of 10 mm, and total depth of 10 mm. The feed rate is 200 mm/min and the cut length per pass is 100 mm. How long will the machining take (in minutes), assuming only linear cutting time?

A 12.5 minutes

B 25 minutes

C 50 minutes

D 20 minutes

💡 Hint

Calculate passes for depth, passes for step-over, then total passes and time.

Depth passes = 10/10 = 1; step-over passes = 100/(8*0.5) = 25; total passes = 1*25=25; time = (25*100)/200 = 12.5 minutes.

🔧 Debug

expert

Find the error in this CNC depth of cut loop script

This pseudo-code loops through depth passes but produces an infinite loop. What is the error? ``` depth = 10 depth_per_pass = 2 current_depth = 0 while current_depth < depth: print(f"Cutting at depth {current_depth} mm") ```

CNC Programming

depth = 10
depth_per_pass = 2
current_depth = 0
while current_depth < depth:
    print(f"Cutting at depth {current_depth} mm")

A The depth_per_pass variable should be initialized to zero.

B The comparison operator should be <= instead of < in the while condition.

C The print statement syntax is incorrect and causes a runtime error.

D The variable current_depth is never updated inside the loop, causing an infinite loop.

💡 Hint

Check if the loop variable changes inside the loop.

Without updating current_depth inside the loop, the condition never becomes false, causing an infinite loop.