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CNC Programmingscripting~10 mins

Finishing strategies (contour, scallop) in CNC Programming - Interactive Code Practice

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Practice - 5 Tasks
Answer the questions below
1fill in blank
easy

Complete the code to select the finishing strategy for a smooth outer edge.

CNC Programming
G01 X[1] Y0 F100 ; Move to start point for finishing
Drag options to blanks, or click blank then click option'
Acontour
Bscallop
Cdrill
Dpocket
Attempts:
3 left
💡 Hint
Common Mistakes
Choosing 'scallop' which is for internal surface finishing.
2fill in blank
medium

Complete the code to set the finishing strategy that removes small surface irregularities.

CNC Programming
M06 T1 ; Tool change to finishing tool
G01 [1] ; Start finishing pass
Drag options to blanks, or click blank then click option'
Ascallop
Bcontour
Cdrill
Drough
Attempts:
3 left
💡 Hint
Common Mistakes
Using 'contour' which is for edges, not surface smoothing.
3fill in blank
hard

Fix the error in the finishing strategy command to correctly apply a scallop finish.

CNC Programming
G01 X10 Y10 F200 ; Move to start
G01 [1] ; Apply finishing
Drag options to blanks, or click blank then click option'
Acontour
Bscallop
Cpocket
Ddrill
Attempts:
3 left
💡 Hint
Common Mistakes
Using 'contour' which only follows edges, not surface.
4fill in blank
hard

Fill both blanks to create a finishing pass that uses contour strategy with feed rate 150.

CNC Programming
G01 [1] F[2] ; Start finishing pass
Drag options to blanks, or click blank then click option'
Acontour
Bscallop
C150
D200
Attempts:
3 left
💡 Hint
Common Mistakes
Mixing scallop with contour or wrong feed rate.
5fill in blank
hard

Fill all three blanks to define a finishing pass using scallop strategy, feed rate 120, and tool number 2.

CNC Programming
M06 T[1] ; Tool change
G01 [2] F[3] ; Start finishing pass
Drag options to blanks, or click blank then click option'
A1
Bscallop
C120
D2
Attempts:
3 left
💡 Hint
Common Mistakes
Using wrong tool number or finishing strategy.

Practice

(1/5)
1. Which finishing strategy is best suited for cleaning the edges of a part by following its outline?
easy
A. Scallop finishing
B. Pocket milling
C. Contour finishing
D. Drilling

Solution

  1. Step 1: Understand the purpose of contour finishing

    Contour finishing follows the outline of a part to clean and smooth its edges.

  2. Step 2: Compare with other strategies

    Scallop finishing smooths curved surfaces, pocket milling removes material inside an area, and drilling creates holes.

  3. Final Answer:

    Contour finishing -> Option C

  4. Quick Check:

    Edge cleaning = Contour finishing [OK]
Hint: Edges cleaned by following outline means contour finishing [OK]
Common Mistakes:
  • Confusing scallop finishing with contour finishing
  • Choosing pocket milling for edge finishing
  • Thinking drilling is a finishing strategy
2. Which of the following is the correct syntax to select scallop finishing in a CNC program snippet?
easy
A. FINISH STRATEGY = CONTOUR
B. FINISH STRATEGY = SCALLOP
C. FINISH = SCALLOP
D. STRATEGY = SCALLOP_FINISH

Solution

  1. Step 1: Identify the correct keyword and value

    The standard syntax uses 'FINISH STRATEGY = SCALLOP' to select scallop finishing.

  2. Step 2: Check other options for syntax errors

    Options B, C, and D use incorrect keywords or incomplete values.

  3. Final Answer:

    FINISH STRATEGY = SCALLOP -> Option B

  4. Quick Check:

    Correct syntax = FINISH STRATEGY = SCALLOP [OK]
Hint: Look for exact keyword 'FINISH STRATEGY = SCALLOP' [OK]
Common Mistakes:
  • Using incomplete or wrong keywords
  • Mixing contour and scallop keywords
  • Missing equal sign or wrong casing
3. Given this CNC code snippet for scallop finishing:
TOOLPATH FINISH SCALLOP
  STEP_OVER = 0.5
  CUT_DEPTH = 0.2
END_TOOLPATH

What is the main effect of reducing the STEP_OVER value?
medium
A. Increase surface smoothness by making tool passes closer
B. Decrease machining time by skipping passes
C. Increase cut depth per pass
D. Change tool diameter automatically

Solution

  1. Step 1: Understand STEP_OVER in scallop finishing

    STEP_OVER controls the distance between tool passes; smaller values mean closer passes.

  2. Step 2: Effect of reducing STEP_OVER

    Closer passes improve surface smoothness but increase machining time.

  3. Final Answer:

    Increase surface smoothness by making tool passes closer -> Option A

  4. Quick Check:

    Smaller STEP_OVER = smoother surface [OK]
Hint: Smaller step over means closer passes and smoother finish [OK]
Common Mistakes:
  • Thinking smaller step over reduces machining time
  • Confusing step over with cut depth
  • Assuming tool diameter changes automatically
4. Identify the error in this contour finishing CNC code snippet:
TOOLPATH FINISH CONTOUR
  STEP_OVER = 1.0
  CUT_DEPTH = -0.1
END_TOOLPATH
medium
A. Missing tool diameter specification
B. STEP_OVER value is too large for contour finishing
C. FINISH keyword should be SCALLOP, not CONTOUR
D. CUT_DEPTH should be positive, not negative

Solution

  1. Step 1: Check CUT_DEPTH value

    CUT_DEPTH represents how deep the tool cuts; it should be positive to indicate depth.

  2. Step 2: Analyze other parameters

    STEP_OVER can be 1.0 if suitable, tool diameter is optional here, and CONTOUR is correct for contour finishing.

  3. Final Answer:

    CUT_DEPTH should be positive, not negative -> Option D

  4. Quick Check:

    Negative CUT_DEPTH is invalid [OK]
Hint: Cut depth must be positive number in finishing [OK]
Common Mistakes:
  • Ignoring negative cut depth as error
  • Assuming STEP_OVER is always too large
  • Confusing contour and scallop keywords
5. You want to finish a complex curved surface with minimal scallop marks and efficient machining time. Which combination of finishing strategy and parameter adjustment is best?
hard
A. Use scallop finishing with a small STEP_OVER value
B. Use contour finishing with a large STEP_OVER value
C. Use scallop finishing with a large CUT_DEPTH value
D. Use contour finishing with a small CUT_DEPTH value

Solution

  1. Step 1: Choose finishing strategy for curved surfaces

    Scallop finishing is designed to smooth curved surfaces effectively.

  2. Step 2: Adjust parameters for minimal scallop marks and efficiency

    A small STEP_OVER reduces scallop marks by making passes closer, balancing smoothness and machining time.

  3. Final Answer:

    Use scallop finishing with a small STEP_OVER value -> Option A

  4. Quick Check:

    Curved surface + small STEP_OVER = smooth finish [OK]
Hint: Small step over + scallop finishing smooths curves best [OK]
Common Mistakes:
  • Choosing contour finishing for curved surfaces
  • Using large STEP_OVER causing rough finish
  • Increasing CUT_DEPTH unnecessarily