NIMS CNC MILLING LEVEL I CERTIFICATION EXAM – QUESTIONS AND ANSWERS | VERIFIED
AND WELL DETAILED ANSWERS | PLUS RATIONALES | GUARANTEED PASS | LATEST EXAM
UPDATE
Core Domains
1. Safety, Personal Protective Equipment (PPE), and Machine Shop Practices
2. CNC Milling Machine Components, Controls, and Functions
3. Coordinate Systems, Axes, and Machine Setup
4. Workholding, Toolholding, and Setup Procedures
5. Blueprint Reading, Geometric Tolerancing, and Part Dimensioning
6. Cutting Tool Selection, Speeds, Feeds, and Toolpath Strategies
7. G-Code and M-Code Programming Fundamentals
8. Quality Control, Inspection Techniques, and Statistical Process Control
9. Mathematics for Machinists, including Trigonometry and Geometry
10. Professionalism, Ethics, and Communication in the Manufacturing Environment
Introduction
The NIMS CNC Milling Level I Certification Exam is designed to assess the foundational skills and
theoretical knowledge required of an entry-level CNC milling machinist. This comprehensive
assessment blends theoretical understanding with practical, scenario-based questions that reflect the
realities of a modern machine shop. Candidates will be tested on their ability to interpret engineering
blueprints, select and apply appropriate speeds and feeds, set up workholding and toolholding
devices, and write and verify basic G-code programs. This exam emphasizes critical thinking,
troubleshooting, and adherence to safety and quality standards. Success requires not only memorizing
facts but also applying knowledge to solve real-world machining challenges, ensuring the candidate is
prepared for the responsibilities and decision-making required in a professional manufacturing
environment.
SECTION ONE: QUESTIONS 1-100
1. When using a standard outside micrometer, what is the correct procedure for taking a
measurement to ensure the most accurate and repeatable result?
A. Tighten the thimble until it is very difficult to turn and then back it off slightly.
B. Use the ratchet stop or friction thimble to apply a consistent, standardized force.
C. Close the micrometer directly on the part and use the lock nut to secure the reading.
D. Only measure the part at the same location as the previous measurement.
🟢B
🔴 Explanation: Using the ratchet stop or friction thimble is the standard procedure to ensure that
a consistent amount of torque is applied to the spindle. This eliminates user-to-user variability and
prevents over-tightening, which can damage the micrometer or distort the measurement of soft
materials.
2. Which M-code is used to command a program stop, allowing the operator to check a part
dimension or clear chips, and then restart the cycle by pressing the cycle start button?
,A. M30
B. M01
C. M00
D. M02
🟢C
🔴 Explanation: M00 is a program stop. When the control reads M00, it stops all spindle and
coolant functions and halts program execution. The operator can then perform manual tasks.
Pressing the cycle start button resumes the program from the next block. M01 is an optional stop,
which only works if the operator has activated the switch.
3. A 3-flute, 0.5-inch diameter high-speed steel end mill will be used to mill a slot in a block of
1018 steel. Using the manufacturer's recommended cutting speed of 100 SFM, what is the correct
spindle speed in RPM?
A. 382 RPM
B. 600 RPM
C. 764 RPM
D. 955 RPM
🟢C
🔴 Explanation: The formula for spindle speed is RPM = (Cutting Speed x 3.82) / Diameter. (100
SFM x 3.82) / 0.5 inch = 764 RPM. The number of flutes is not a factor in calculating spindle speed,
which is based solely on cutting speed and tool diameter.
4. According to standard machining practice, what is the primary function of the G54 through
G59 commands in a CNC milling program?
A. To select the tool offset for the next operation.
B. To call a subprogram for a repeated machining pattern.
C. To establish a zero return reference point for the machine axes.
D. To define a workpiece coordinate system for the part origin.
🟢D
🔴 Explanation: G54 to G59 are work offset commands. They allow the programmer to set multiple
part origins within a single program. By defining the X, Y, and Z zero points for each work
coordinate system, the operator can machine multiple vises or setups without re-zeroing the
machine.
5. A G82 canned cycle is used primarily for what application on a CNC milling machine?
A. Boring a large diameter hole with a single-point tool.
B. Drilling a hole with a dwell at the bottom to ensure a flat bottom.
C. Tapping a hole to a specific depth using a rigid tap.
D. Spot drilling a hole to create a chamfer on the surface.
🟢B
🔴 Explanation: The G82 canned cycle is a spot-drilling or counter-boring cycle. It drills a hole and
then has a dwell at the bottom. The dwell is used to spot-face or counterbore a hole, ensuring the
bottom of the feature is flat. A simple G81 cycle would not have this dwell.
, 6. When reading a blueprint, what does the feature control frame of a geometric tolerance
typically include?
A. The part number, revision level, and material specifications.
B. The geometric characteristic symbol, tolerance value, and datums.
C. The surface finish requirement and the machining process to be used.
D. The dimension values and their associated tolerances.
🟢B
🔴 Explanation: A feature control frame is a rectangle divided into sections. It contains the
geometric characteristic symbol (e.g., flatness, perpendicularity, position), the total tolerance value,
and letters identifying the datum reference frame from which the tolerance is applied.
7. You are setting up a job in a vise and need to indicate the fixed jaw. You find the jaw is out of
square by 0.003 inches over a 6-inch length. What is the most appropriate action to take?
A. Continue the setup as 0.003 inches is within the standard tolerance for a vise.
B. Tap the part into position using a dead-blow hammer each time to compensate.
C. Use a soft-jaw grip and indicate the part, not the vise jaw, before tightening.
D. Scrap the vise and use a different workholding method for the entire job.
🟢C
🔴 Explanation: If the fixed jaw is out of square, the best practice is to use soft jaws that have been
machined in place to be parallel to the spindle. Alternatively, you should indicate the surface of the
part itself that will be used as a reference, and tap it into alignment before final clamping, rather
than relying on the vise's fixed jaw.
8. How is the feed rate for a milling cutter typically expressed in a program?
A. Inches per minute (IPM) or millimeters per minute (mm/min).
B. Inches per revolution (IPR) or millimeters per revolution (mm/rev).
C. Feet per minute (FPM) or meters per minute (m/min).
D. Revolutions per minute (RPM) or rotations per minute.
🟢A
🔴 Explanation: Feed rate in milling is normally programmed as a linear feed rate, which is the
distance the table moves per minute. This is expressed in inches per minute (IPM) or millimeters per
minute (mm/min). The G94 code is used for this. IPR is more common for turning operations.
9. A finished part dimension is specified as 2.500 ± 0.005 inches. After machining, you measure
the part and get a value of 2.503 inches. What is the correct disposition of this part?
A. The part is acceptable and within tolerance.
B. The part can be reworked to bring it closer to the nominal size.
C. The part is outside the specified tolerance and must be scrapped.
D. The part is acceptable as long as it was measured on a calibrated instrument.
🟢A
🔴 Explanation: The tolerance is 2.500 ± 0.005, meaning the acceptable range is from 2.495 to
2.505 inches. A measurement of 2.503 inches falls within this range, so the part is within tolerance
and is acceptable.
AND WELL DETAILED ANSWERS | PLUS RATIONALES | GUARANTEED PASS | LATEST EXAM
UPDATE
Core Domains
1. Safety, Personal Protective Equipment (PPE), and Machine Shop Practices
2. CNC Milling Machine Components, Controls, and Functions
3. Coordinate Systems, Axes, and Machine Setup
4. Workholding, Toolholding, and Setup Procedures
5. Blueprint Reading, Geometric Tolerancing, and Part Dimensioning
6. Cutting Tool Selection, Speeds, Feeds, and Toolpath Strategies
7. G-Code and M-Code Programming Fundamentals
8. Quality Control, Inspection Techniques, and Statistical Process Control
9. Mathematics for Machinists, including Trigonometry and Geometry
10. Professionalism, Ethics, and Communication in the Manufacturing Environment
Introduction
The NIMS CNC Milling Level I Certification Exam is designed to assess the foundational skills and
theoretical knowledge required of an entry-level CNC milling machinist. This comprehensive
assessment blends theoretical understanding with practical, scenario-based questions that reflect the
realities of a modern machine shop. Candidates will be tested on their ability to interpret engineering
blueprints, select and apply appropriate speeds and feeds, set up workholding and toolholding
devices, and write and verify basic G-code programs. This exam emphasizes critical thinking,
troubleshooting, and adherence to safety and quality standards. Success requires not only memorizing
facts but also applying knowledge to solve real-world machining challenges, ensuring the candidate is
prepared for the responsibilities and decision-making required in a professional manufacturing
environment.
SECTION ONE: QUESTIONS 1-100
1. When using a standard outside micrometer, what is the correct procedure for taking a
measurement to ensure the most accurate and repeatable result?
A. Tighten the thimble until it is very difficult to turn and then back it off slightly.
B. Use the ratchet stop or friction thimble to apply a consistent, standardized force.
C. Close the micrometer directly on the part and use the lock nut to secure the reading.
D. Only measure the part at the same location as the previous measurement.
🟢B
🔴 Explanation: Using the ratchet stop or friction thimble is the standard procedure to ensure that
a consistent amount of torque is applied to the spindle. This eliminates user-to-user variability and
prevents over-tightening, which can damage the micrometer or distort the measurement of soft
materials.
2. Which M-code is used to command a program stop, allowing the operator to check a part
dimension or clear chips, and then restart the cycle by pressing the cycle start button?
,A. M30
B. M01
C. M00
D. M02
🟢C
🔴 Explanation: M00 is a program stop. When the control reads M00, it stops all spindle and
coolant functions and halts program execution. The operator can then perform manual tasks.
Pressing the cycle start button resumes the program from the next block. M01 is an optional stop,
which only works if the operator has activated the switch.
3. A 3-flute, 0.5-inch diameter high-speed steel end mill will be used to mill a slot in a block of
1018 steel. Using the manufacturer's recommended cutting speed of 100 SFM, what is the correct
spindle speed in RPM?
A. 382 RPM
B. 600 RPM
C. 764 RPM
D. 955 RPM
🟢C
🔴 Explanation: The formula for spindle speed is RPM = (Cutting Speed x 3.82) / Diameter. (100
SFM x 3.82) / 0.5 inch = 764 RPM. The number of flutes is not a factor in calculating spindle speed,
which is based solely on cutting speed and tool diameter.
4. According to standard machining practice, what is the primary function of the G54 through
G59 commands in a CNC milling program?
A. To select the tool offset for the next operation.
B. To call a subprogram for a repeated machining pattern.
C. To establish a zero return reference point for the machine axes.
D. To define a workpiece coordinate system for the part origin.
🟢D
🔴 Explanation: G54 to G59 are work offset commands. They allow the programmer to set multiple
part origins within a single program. By defining the X, Y, and Z zero points for each work
coordinate system, the operator can machine multiple vises or setups without re-zeroing the
machine.
5. A G82 canned cycle is used primarily for what application on a CNC milling machine?
A. Boring a large diameter hole with a single-point tool.
B. Drilling a hole with a dwell at the bottom to ensure a flat bottom.
C. Tapping a hole to a specific depth using a rigid tap.
D. Spot drilling a hole to create a chamfer on the surface.
🟢B
🔴 Explanation: The G82 canned cycle is a spot-drilling or counter-boring cycle. It drills a hole and
then has a dwell at the bottom. The dwell is used to spot-face or counterbore a hole, ensuring the
bottom of the feature is flat. A simple G81 cycle would not have this dwell.
, 6. When reading a blueprint, what does the feature control frame of a geometric tolerance
typically include?
A. The part number, revision level, and material specifications.
B. The geometric characteristic symbol, tolerance value, and datums.
C. The surface finish requirement and the machining process to be used.
D. The dimension values and their associated tolerances.
🟢B
🔴 Explanation: A feature control frame is a rectangle divided into sections. It contains the
geometric characteristic symbol (e.g., flatness, perpendicularity, position), the total tolerance value,
and letters identifying the datum reference frame from which the tolerance is applied.
7. You are setting up a job in a vise and need to indicate the fixed jaw. You find the jaw is out of
square by 0.003 inches over a 6-inch length. What is the most appropriate action to take?
A. Continue the setup as 0.003 inches is within the standard tolerance for a vise.
B. Tap the part into position using a dead-blow hammer each time to compensate.
C. Use a soft-jaw grip and indicate the part, not the vise jaw, before tightening.
D. Scrap the vise and use a different workholding method for the entire job.
🟢C
🔴 Explanation: If the fixed jaw is out of square, the best practice is to use soft jaws that have been
machined in place to be parallel to the spindle. Alternatively, you should indicate the surface of the
part itself that will be used as a reference, and tap it into alignment before final clamping, rather
than relying on the vise's fixed jaw.
8. How is the feed rate for a milling cutter typically expressed in a program?
A. Inches per minute (IPM) or millimeters per minute (mm/min).
B. Inches per revolution (IPR) or millimeters per revolution (mm/rev).
C. Feet per minute (FPM) or meters per minute (m/min).
D. Revolutions per minute (RPM) or rotations per minute.
🟢A
🔴 Explanation: Feed rate in milling is normally programmed as a linear feed rate, which is the
distance the table moves per minute. This is expressed in inches per minute (IPM) or millimeters per
minute (mm/min). The G94 code is used for this. IPR is more common for turning operations.
9. A finished part dimension is specified as 2.500 ± 0.005 inches. After machining, you measure
the part and get a value of 2.503 inches. What is the correct disposition of this part?
A. The part is acceptable and within tolerance.
B. The part can be reworked to bring it closer to the nominal size.
C. The part is outside the specified tolerance and must be scrapped.
D. The part is acceptable as long as it was measured on a calibrated instrument.
🟢A
🔴 Explanation: The tolerance is 2.500 ± 0.005, meaning the acceptable range is from 2.495 to
2.505 inches. A measurement of 2.503 inches falls within this range, so the part is within tolerance
and is acceptable.
