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Quizzes > Programming & Software

CNC Test: General Machinist Skills Quiz

Quick, free CNC machinist test for programming and G-code. Instant results.

Editorial: Review CompletedCreated By: Tobias KirschUpdated Oct 23, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art style CNC test quiz illustration with G-code symbols drill bit and tools on coral background

This CNC test helps you check your programming, G-code commands, and toolpath basics, with instant feedback on what to review next. For extra practice, try a g code practice test and a caliper measurement test, or broaden your fundamentals with a mechanical aptitude test. Take the quiz to see where you can improve.

What G-code command is used for linear interpolation?
G02
G03
G01
G00
The G01 command is used for linear interpolation, moving the tool in a straight line at the programmed feed rate. G00 is for rapid positioning, while G02 and G03 perform circular moves. Understanding G01 is essential for precise contouring and part profiling.
Which G-code sets the machine to rapid positioning mode?
G02
G01
G03
G00
G00 is the modal code for rapid positioning, commanding the machine to move the tool at maximum speed. It is not used for cutting but for non-cutting traverses to reduce cycle time. Using G00 appropriately helps optimize overall machining efficiency.
Which letter specifies the feed rate in a CNC program?
M
G
S
F
The F word address sets the feed rate in units per minute (G94) or per revolution (G95). G codes define motion types, S controls spindle speed, and M handles miscellaneous functions. Correct feed settings ensure tool life and surface finish.
Which M-code turns the spindle on clockwise?
M03
M06
M05
M04
M03 engages the spindle in the clockwise direction, which is the most common rotation for cutting. M04 is counterclockwise, M05 stops the spindle, and M06 triggers a tool change. Proper spindle commands avoid tool damage.
Which G-code selects metric programming in millimeters?
G94
G20
G90
G21
G21 switches the machine to metric units (millimeters). G20 sets inches, G90 selects absolute positioning, and G94 sets feed per minute. Unit selection is critical for correct dimensions.
Which G-code sets the machine to absolute positioning mode?
G92
G91
G94
G90
G90 selects absolute positioning, referencing all coordinates from the program origin. G91 is incremental mode, G92 sets position offsets, and G94 defines feed mode. Using the correct mode prevents coordinate errors.
Which command sets the machine to incremental positioning?
G92
G90
G94
G91
G91 enables incremental programming, meaning each move is relative to the current tool position. G90 is absolute mode, G92 sets offsets, and G94 selects feed per minute. Mixing modes without care leads to part errors.
Which G-code applies tool length offset compensation?
G42
G43
G40
G41
G43 applies the tool length offset stored in the selected tool offset register (H word). G41 and G42 are cutter compensation, and G40 cancels compensation. Tool length offsets ensure accurate Z-axis positioning.
Which M-code turns the coolant on?
M10
M07
M09
M08
M08 activates the flood coolant pump. M07 turns on mist coolant, M09 turns all coolant off, and M10 is a door interlock on some machines. Proper coolant use prolongs tool life and improves finish.
Which code ends the program and rewinds to start?
M00
M30
M02
M06
M30 ends the program, stops the machine, and rewinds the program to the start. M02 ends without rewind, M00 is an optional stop, and M06 is a tool change. Proper program termination prevents crashes.
Which axis typically represents vertical movement on a CNC mill?
X axis
Z axis
A axis
Y axis
On most CNC mills, the Z axis is vertical (up and down), while X and Y are horizontal. A is a rotary axis. Correct axis identification is critical for three-dimensional toolpath planning.
What is the function of the M00 command in a CNC program?
Coolant on
Spindle stop
Optional stop
Program end
M00 causes an optional stop in the program and waits for operator action. M01 is another optional stop when enabled, M02 ends the program, and M05 stops the spindle. Optional stops are useful for checks or measurements.
Which G-code is used to cancel cutter diameter compensation?
G41
G42
G43
G40
G40 cancels any active cutter radius compensation in the program. G41 and G42 apply left and right compensation, respectively, and G43 applies tool length offset. Canceling compensation ensures the machine returns to programmed path.
What does the G20 command specify?
Absolute mode
Metric units
Inch units
Incremental mode
G20 sets programming in inches, while G21 sets millimeters. G90 and G91 control absolute and incremental modes, respectively. Unit selection is fundamental to correct part dimensions.
Which M-code calls a subprogram?
M98
M99
M97
M30
M98 calls a subprogram stored in memory, allowing modular code reuse. M99 returns from a subprogram, M97 can call local subroutines, and M30 ends the program. Using subprograms simplifies complex routines.
Which G-code command is used for circular interpolation in the clockwise direction?
G03
G04
G02
G01
G02 performs clockwise circular interpolation, requiring I, J (and K for 3D) parameters for the center point. G03 is counterclockwise, G01 is linear, and G04 is dwell. Correct circular commands are key to accurate arcs.
What is the primary function of tool length offset in CNC machining?
Compensate tool length differences
Set coolant flow
Compensate tool radius
Adjust spindle speed
Tool length offsets account for variations in tool length so that the Z-axis position is accurate for each tool. This compensation is stored in the offset register and called via G43/H. Without it, tools with different lengths would cut at incorrect depths.
In CNC milling, what does the abbreviation RPM stand for?
Rounds per meter
Rising per minute
Revolutions per minute
Rotations per millisecond
RPM measures spindle speed in revolutions per minute, indicating how fast the cutting tool or workpiece spins. It directly affects surface finish, tool life, and heat generation. Correct RPM selection is crucial for efficient machining.
What does the M06 command do in a CNC program?
End program
Spindle stop
Tool change
Start coolant
M06 initiates a tool change sequence, prompting the machine to swap to the specified tool offset. It pauses motion until the change is complete, ensuring the correct tool is in the spindle. Proper tool calls prevent crashes and ensure dimensional accuracy.
Which G-code initiates a basic drilling canned cycle?
G83
G80
G82
G81
G81 is the simple drilling cycle, moving the tool to a specified depth at the feed rate, then retracting. G82 includes a dwell, G83 is peck drilling, and G80 cancels canned cycles. Canned cycles simplify repetitive operations.
In a G81 drilling cycle, which parameter defines the retract height above the workpiece?
D
R
L
Q
In G81, the R word sets the retract or clearance plane above the workpiece to which the tool returns after drilling. D is for depth offset in some controls, Q is peck amount in G83, and L is loop count for repeated cycles. Proper retract height avoids collisions.
What additional parameters are required for programming G02 compared to G01?
I, J (and K)
Spindle speed
Feed rate
Tool number
G02 and G03 require center point offsets specified by I, J (and K for Z-axis) to define circular arcs. G01 only needs endpoint coordinates and feed rate. Including center offsets ensures correct radius and path.
What is the purpose of the G73 cycle in drilling operations?
Boring with dwell
Simple drill
Deep peck drilling
Face milling
G73 is a high-speed peck drilling cycle used for shallow, repeated pecks to evacuate chips when drilling harder materials. It retracts slightly between pecks to clear chips, reducing tool breakage. G83 is a deep peck cycle with full retracts, and G85 is boring.
Which letter address sets the spindle speed in a CNC program?
S
F
H
T
The S word address sets the desired spindle speed in revolutions per minute. F is feed rate, T is tool selection, and H is tool length offset. Always specify spindle speed before turning the spindle on with M03/M04.
What is the correct sequence to start the spindle at 1200 RPM clockwise?
G97 S1200 M03
S1200 M03
M03 S1200
S1200 G97 M03
Typically, you specify S1200 to set the spindle speed and then M03 to start the spindle clockwise. On most controls, the order S-word then M-word ensures the speed is updated before rotation begins. G97 is constant RPM mode in turning.
How would you program a dwell of 3 seconds?
G04 P3
M04 P3
G00 P3
G03 P3
G04 is the dwell command, and P specifies the dwell time (in seconds or milliseconds depending on the control). G03 is counterclockwise arc, M04 is spindle CCW, and G00 is rapid move. Dwell can help with spot drilling or chip clearing.
Which G-code cancels any active canned cycle?
G79
G82
G83
G80
G80 cancels the current canned cycle (drilling, boring, etc.) and returns the machine to default motion mode. G82 and G83 are specific drilling cycles, and G79 is non-standard. Always cancel cycles before normal moves.
How is cutter radius compensation applied on the right side of the programmed path?
G42
G43
G41
G40
G42 applies cutter radius compensation on the right side of the programmed path, offsetting the tool centerline by the cutter radius. G41 applies compensation on the left, G40 cancels it, and G43 is tool length compensation. Proper application ensures accurate part dimensions.
What is the default machining plane selected by G17?
None of the above
YZ plane
XY plane
XZ plane
G17 selects the XY plane for circular interpolation and canned cycles. G18 selects XZ, G19 selects YZ. Plane selection is crucial for correct arc orientation.
What function does the M01 command perform?
Cycle stop
Program end
Optional stop
Unconditional stop
M01 is an optional stop, similar to M00 but only executed when optional stops are enabled on the control. This allows conditional pauses for inspection without stopping every run. Proper use aids quality control.
In a G83 drilling cycle, what does the Q word specify?
Cycle count
Retract height
Peck depth
Dwell time
In G83 (deep peck drilling), Q defines the depth of each peck. The tool pecks down by Q, retracts slightly to clear chips, and repeats until the programmed depth is reached. R sets the retract plane, and L sets repetition.
What is the effect of the G54 command in CNC programming?
Set incremental mode
Start spindle
Select work coordinate system #1
Cancel compensation
G54 selects work coordinate system number one, shifting the program origin to a preset fixture location. G55 - G59 select other offsets. Proper work offsets allow multiple parts or fixtures.
In a multi-axis CNC machine, what does G68 perform?
Polar coordinate
Mirror image
Tool change
Coordinate rotation
G68 rotates the coordinate system by a specified angle about a defined point, enabling program rotation without rewriting coordinates. G69 cancels the rotation. This is useful for machining angled features.
Which code cancels coordinate rotation introduced by G68?
G70
G71
G69
G67
G69 cancels the coordinate rotation set by G68, returning to the original Cartesian axes. G67 is mirror cancel on some controls, and G70/G71 are turning cycles on lathes. Knowing cancellation codes avoids programming errors.
How do you program a mirror image of a toolpath about the Y-axis?
G53 Y-1
G50 Y-1
G52 Y-1
G51 Y-1
G51 with an axis scale factor of -1 inverts the toolpath across that axis, creating a mirror image. G52 sets a temporary work offset, G53 is machine coordinates, and G50 cancels scaling. Mirror scaling expedites symmetric part programming.
In CNC turning, what does G96 control?
Spindle speed
Feed per revolution
Constant surface speed
Tool offset
G96 engages constant surface speed (CSS) control, automatically adjusting spindle RPM to maintain a constant cutting speed at the workpiece surface. G97 cancels CSS and sets fixed RPM. CSS optimizes tool life and finish.
Which G-code is used to call a macro subprogram with argument passing?
G65
G68
G67
G66
G65 calls a canned macro subprogram and allows passing parameters to user-defined variables. G66 remains modal, and G67 cancels modal macro calls on some controls. Macros enable advanced customization.
What symbol denotes a macro variable in FANUC Macro B programming?
$
:
#
@
In FANUC Macro B, variables are referenced with the hash symbol (#) followed by a number or name. Local variable names begin with an underscore. Using # ensures the control recognizes the variable for calculation and logic.
When programming G02 for circular interpolation, what does the I parameter represent?
Spindle speed increment
Distance from start point to center in X
Number of repeats
Feed rate in I direction
In G02/G03, I specifies the X-axis offset from the start point to the center of the circle. J is the Y offset (and K for Z). Together they define the radius and center location for the arc move. Correct offsets ensure accurate arcs.
What is the function of G53 in CNC machining?
Go to machine coordinate
Select work offset
Activate mirror mode
Enable polar programming
G53 performs a move in machine (absolute) coordinates, bypassing any work offsets. This is typically used for safe moves to reference points or tool changes. G54 - G59 select work offsets. Machine coordinate moves avoid offset confusion.
Which canned cycle is used for boring with dwell in CNC milling?
G82
G85
G81
G83
G85 is the boring cycle with dwell at bottom, moving at feed rate, dwelling, then retracting. G82 is drilling with dwell, G81 is simple drilling, and G83 is peck drilling. Selecting the correct cycle ensures hole quality.
What does G43.2 accomplish on advanced CNC controls?
Cancel tool length offset
Activate polar mode
Dynamic tool length measurement
Apply cutter compensation
G43.2 on some controls triggers a tool length measurement routine using a touch probe or tool presetter. G43 applies a fixed offset, G44 reverses offset, and G49 cancels it. Dynamic measurement improves setup speed.
In a G76 thread cutting cycle on a lathe, what does the P parameter specify?
Pitch of thread
Spindle speed
Depth of first pass
Number of finishing passes
In the Fanuc G76 threading cycle, P sets the number of finishing passes, controlling how many times the tool repeats at the final depth. L sets the number of initial rough passes, and Q sets the percentage depth per rough pass. Proper settings ensure thread quality.
What feed mode is activated by G95 in CNC turning?
Constant surface speed
Incremental feed
Feed per minute
Feed per revolution
G95 sets the feed mode to units per revolution, ensuring a consistent chip load per spindle turn. G94 is feed per minute. Using G95 is essential for turn operations to maintain surface finish and tool life.
How would you program a helical interpolation for a hole on a CNC mill?
G03 with no Z movement
G01 with Z and no arc code
G81 with Q feed
G02 with I, J and simultaneous Z feed
Helical interpolation uses G02 or G03 with I and J to define the circle and a Z value in the same block for axial feed, creating a spiral. G01 is linear, and canned cycles don't support continuous spiral. Helical drilling is efficient and reduces chip load.
In FANUC Macro B programming, how do you return from a subroutine back to the main program?
M98
M99
M30
M97
M99 is used to return from a subprogram or macro back to the calling program. M98 calls a subprogram, M97 can call local subroutines, and M30 ends the program. Correct subroutine returns prevent endless loops.
How do you define a local variable in FANUC Macro B programming?
Use # followed by number
Define in a G65 call
Start name with underscore after #
Use @ before name
In FANUC Macro B, local variables must begin with an underscore and be preceded by a #, for example #<_count>. Global variables use #1 - #33. This prevents naming conflicts and ensures local scope.
Which G-code enables continuous path mode to minimize dwell between blocks?
G64
G62
G61
G63
G64 sets continuous path mode, allowing the machine to blend motions at block boundaries for smoother toolpaths and reduced cycle time. G61 is exact stop, G62 is PVT corner smoothing, and G63 is TSC. Continuous path is key in high-speed machining.
Which G-code activates polar coordinate programming?
G18
G16
G17
G15
G16 enables polar coordinate programming, where positions are defined by angle and radius. G15 cancels polar mode, G17/G18 select machining planes. Polar mode simplifies circular pattern programming.
Which G-code returns all axes to machine home via machine coordinates?
G53
G30
G92
G28
G28 moves the machine to the reference position via machine coordinates, often used for safe tool changes. G30 can move to secondary home, G53 moves in machine coord but doesn't necessarily go home, and G92 sets offsets. Proper use prevents collisions.
Which G-code cycle is commonly used for thread milling on HAAS CNC mills?
G84
G92
G88
G76
On HAAS CNC mills, G76 is the thread milling cycle, allowing precise control of multiple passes to form threads. G84 is tapping, G88 is boring, and G92 sets offsets. Thread milling ensures accuracy and reduces tool wear.
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Study Outcomes

  1. Analyze CNC Test Patterns -

    By taking the quiz, readers will dissect common CNC test patterns and understand how different program structures affect machining outcomes.

  2. Interpret G-code Commands -

    Readers will interpret essential G-code commands - such as G00, G01, and M-codes - to determine tool path and machine behavior.

  3. Apply Tool Movement Principles -

    Readers will apply principles of tool movement, feed rates, and spindle speeds to anticipate machining operations and their impacts on part quality.

  4. Evaluate Machinist Scenarios -

    Readers will evaluate realistic machinist test scenarios to troubleshoot programming errors and optimize operational parameters.

  5. Identify Performance Gaps -

    Readers will identify their strengths and areas for improvement in CNC programming and tool handling before taking an actual machinist assessment test.

  6. Optimize CNC Exam Preparation -

    Readers will optimize their CNC exam preparation strategy by focusing on key G-code concepts and toolpath logic highlighted in the quiz.

Cheat Sheet

  1. G-Code Fundamentals -

    Master the core G-codes like G0 for rapid moves, G1 for precise linear cuts, and G2/G3 for clockwise and counterclockwise arcs; a handy mnemonic is "Rapid Lions Glide Clockwise." According to ISO 6983, these commands form the backbone of any CNC program and often appear on your cnc test. Practicing simple code snippets builds confidence for both a machinist test and cnc exam.

  2. Coordinate Systems & Work Offsets -

    Understand G54 - G59 work offsets to shift your part origin without rewriting code; for example, G54 X0 Y0 Z0 sets the primary machine zero (NIMS standards). Remember "Fifty-Four First" to recall you always start with G54 in most machinist assessment tests. Accurate offsets prevent costly scrapping and score big points on a cnc test pattern question.

  3. Feed Rate & Spindle Speed Calculations -

    Use the formula Vc = π·D·N/1000 (cutting speed in m/min) to solve spindle speed N = Vc·1000/(π·D). For example, with D = 10 mm and Vc = 120 m/min, N ≈3820 RPM - an essential calculation on any cnc exam. Mastering this ensures you hit optimal surface finish and tool life in a machinist test scenario.

  4. Cutter Compensation & Toolpath Strategies -

    Learn G41/G42 for left/right cutter compensation and decide between climb vs. conventional milling to control chip thickness. A quick tip: "Climb cuts chips thick to thin," which reduces heat but can pull the workpiece - key knowledge for machinist assessment test problems. Simulation of toolpaths helps visualize compensation effects before running real-world operations.

  5. Simulation Practice & Test Pattern Review -

    Run through standard cnc test patterns - pocket milling, circular interpolation, drilling cycles like G83 - in simulation software such as Fusion 360 or NC Viewer. According to MIT OpenCourseWare, visualizing your code in a virtual environment highlights syntax errors and logic flaws before your cnc exam. Regular practice with these patterns boosts speed and accuracy for any machinist test or machinist assessment test.

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