Machinist Red Seal practice test: 25 free exam-style questions with answers
Free Machinist Red Seal practice test: 25 questions with answers, explanations and work-area review, online or as a printable PDF. Ontario 429A.
This free Machinist practice test has 25 original multiple-choice questions spread across the work areas of the Red Seal exam, with the answer and an explanation for each question. The real exam has 135 questions in four hours with a 70% pass mark. These are not real exam questions.
Machinist practice test PDF: all 25 questions, answers and explanations
Machinist Red Seal exam: format, pass mark and how to prepare · Machinist Red Seal exam prep app · Prep options compared
429A is Ontario’s trade code for General Machinist, not a national Red Seal exam number.
These Machinist practice questions follow the official work areas of the Red Seal exam and use the same three question styles as the exam: recall, procedure and critical thinking. Use them as a warm-up before a full timed mock, not as a simulation of the 429A exam.
This practice test
- 25 reviewed questions, no time limit
- Answers, explanations and technical references
- Score by major work area
- Printable PDF version; the page also works without JavaScript
The timed browser demo
- 10 of these questions, 20 minutes, exam-style screen
- Work-area snapshot at the end, like the app
- Progress saved in this browser only
Both are free, need no account, and are separate from the installed app.
Before you begin
Choose one answer per question, then check your score. These 25 questions cover every major work area of the trade but are not a full-length mock or a prediction of passing. Answers stay in this page and are not sent anywhere. Reloading clears your selections.
Explanations can be opened at any time, even without JavaScript. For a first attempt, wait until you have chosen your answers.
Free practice questions with answers
Questions from our public demo, created and reviewed with AI assistance. Answer before opening the explanation, then note the reason for any mistake or uncertain answer. These are independent study exercises, not official exam questions. For workplace tasks, verify the applicable procedures and technical sources.
25 questions across 8 major work activities: Common occupational skills (3) · Benchwork (2) · Power saws (2) · Drill presses (2) · Conventional lathes (5) · Conventional milling machines (5) · Precision grinding machines (2) · CNC machines (4).
All 25 questions, answers and explanations. No account needed.
Question 1 · Common occupational skills
After electrical isolation, a vertical machine axis still tends to descend. What must be addressed before work begins?
Show answer and explanation
Answer: D — Block or restrain the stored mechanical energy.
Electrical isolation does not remove potential energy from an elevated mass.
Question 2 · Benchwork
After a tang-driven insert is installed to the specified depth, what final step may be required before assembly?
Show answer and explanation
Answer: B — Remove the tang; verify insert position and thread.
A retained tang can obstruct a through fastener or contaminate the assembly.
Question 3 · Power saws
Which power saw is normally preferred for repetitive straight cut-off work on bar and structural stock?
Show answer and explanation
Answer: B — A supported horizontal band-saw setup.
Its gravity or controlled-feed head and horizontal blade path suit supported production cut-off work.
Question 4 · Drill presses
Using the common metric approximation tap-drill diameter = major diameter − pitch, what drill is indicated for M10 × 1.5?
Show answer and explanation
Answer: D — 8.5 mm
10.0 − 1.5 = 8.5 mm before considering the exact thread percentage or specified standard.
Question 5 · Conventional lathes
With tool geometry and rigidity unchanged, what is the usual surface-finish effect of lowering feed per revolution?
Show answer and explanation
Answer: C — Feed reduction lowers theoretical roughness
A smaller axial advance separates successive tool-nose tracks by less distance.
Question 6 · Conventional lathes
A diameter is 0.08 mm oversize and the cross-slide dial reads actual radial movement. What nominal additional infeed is required?
Show answer and explanation
Answer: C — 0.04 mm
Removing 0.04 mm from the radius reduces the diameter by 0.08 mm.
Question 7 · Conventional milling machines
Which conventional mill is normally most versatile for one-off work involving end milling, drilling, and top-surface features?
Show answer and explanation
Answer: B — A vertical knee mill.
Its vertical spindle, movable table and common tooling support these varied operations.
Question 8 · Conventional milling machines
A boring head reads radial movement. To enlarge a bore by 0.10 mm, what nominal head adjustment is required?
Show answer and explanation
Answer: C — 0.05 mm outward
A 0.05 mm radial increase enlarges diameter by 0.10 mm.
Question 9 · Precision grinding machines
Which precision grinding machine should be selected to produce a close-tolerance flat face on a rectangular hardened-steel block?
Show answer and explanation
Answer: A — A suitable surface grinder with secure, accurate workholding
A surface grinder is designed to generate controlled flat surfaces with table and cross-feed motion.
Question 10 · CNC machines
A hole is 50 mm from the X datum and 30 mm from the Y datum. With the work origin at the datum intersection and absolute programming active, what endpoint should be programmed?
Show answer and explanation
Answer: D — X50.000 Y30.000
Absolute coordinates state the feature position directly from the work origin.
Question 11 · Common occupational skills
A blind internal groove is unclear in the exterior view. Which drawing information should be used to define it?
Show answer and explanation
Answer: A — The dimensioned section or detail view.
A section exposes internal geometry that hidden lines alone may not define clearly.
Question 12 · Common occupational skills
A shaft is specified as 25.000 +0.000/−0.018 mm. What are its permissible size limits?
Show answer and explanation
Answer: C — 24.982 mm minimum and 25.000 mm maximum
The upper deviation is zero and the lower deviation subtracts 0.018 mm from basic size.
Question 13 · Benchwork
A shaft repeatedly cracks from the corner of a keyway. What design or repair factor should be investigated?
Show answer and explanation
Answer: A — Keyway stress concentration, cyclic loading, surface condition and fatigue strength.
A keyway is a geometric discontinuity that amplifies cyclic stress, so its root condition and the material’s fatigue resistance are central to the investigation.
Question 14 · Power saws
A large solid aluminum billet loads a fine-pitch blade with chips. What blade change should be considered?
Show answer and explanation
Answer: C — Use coarser teeth with adequate gullets and engagement.
A large section produces high chip volume that requires gullet capacity.
Question 15 · Drill presses
A reamed hole is on size at entry but smaller at the bottom. What should be investigated?
Show answer and explanation
Answer: C — Check prehole taper, reamer alignment/runout, wear, chips, fluid, deflection and depth
A reamer tends to follow the existing hole; poor stock distribution or incomplete cutting can leave taper.
Question 16 · Conventional lathes
Ignoring approach, how long does a 120 mm turning pass take at 400 rpm and 0.25 mm/rev?
Show answer and explanation
Answer: A — 1.20 min
Feed rate is 400 × 0.25 = 100 mm/min; 120/100 = 1.20 min.
Question 17 · Conventional lathes
Longitudinal turning is stable, but the tool chatters when feeding radially into a shoulder. What should be evaluated?
Show answer and explanation
Answer: A — Evaluate entering angle, clearance, radial engagement, nose radius, overhang and strategy
Radial feeding changes force direction and can engage more edge length than longitudinal cutting.
Question 18 · Conventional lathes
A short external taper has an included angle of 20°. How should the compound be set when its scale is verified as reading from the work axis?
Show answer and explanation
Answer: C — Set it to the 10° half-angle and feed along the compound
The tool path follows one side of the taper, which is half the included angle.
Question 19 · Conventional milling machines
A four-tooth end mill runs at 600 rpm with 0.08 mm/tooth. What table feed is required?
Show answer and explanation
Answer: C — 192 mm/min
0.08 × 4 × 600 = 192 mm/min.
Question 20 · Conventional milling machines
A four-tooth cutter runs at 900 rpm and table feed is 360 mm/min. What is feed per tooth?
Show answer and explanation
Answer: C — 0.10 mm/tooth
360/(900 × 4) = 0.10 mm/tooth.
Question 21 · Conventional milling machines
A long end mill chatters at a particular rpm and radial engagement. What is the sound correction path?
Show answer and explanation
Answer: B — Shorten overhang or improve support, then test a meaningful speed change and suitable engagement/feed within tool guidance
Rigidity addresses the structural cause and speed/engagement can move the cut to a stable condition.
Question 22 · Precision grinding machines
A part shifts on a magnetic chuck during the first grinding pass. What should be done?
Show answer and explanation
Answer: D — Stop safely, inspect contact and magnetism, clean/stone surfaces, improve pole contact and blocking, reduce force, and use a suitable alternate fixture if holding remains inadequate
Any movement invalidates geometry and creates an ejection hazard.
Question 23 · CNC machines
On a 100 mm bolt circle, what are the X and Y coordinates of the hole at 30° from positive X, with the circle centre at the work origin?
Show answer and explanation
Answer: B — ≈ X43.301 Y25.000
The radius is 50 mm; X = 50 cos 30° = 43.301 and Y = 50 sin 30° = 25.000.
Question 24 · CNC machines
A CNC-turned outside diameter measures 0.06 mm oversize on a control that displays X offsets in diameter values. What magnitude of X wear correction is required?
Show answer and explanation
Answer: C — A 0.06 mm diameter correction in the direction that moves the tool 0.03 mm radially inward
In diameter programming, a 0.06 mm diameter change corresponds to 0.03 mm radial tool motion.
Question 25 · CNC machines
A finish-bored hole is 0.03 mm undersize. The boring tool can be adjusted radially at the cutting edge. What physical adjustment is required before considering control-specific sign?
Show answer and explanation
Answer: D — Move the cutting edge radially outward by 0.015 mm
A radial change affects both sides of the diameter.
0 of 25 answered
Open the timed 10-question browser demo (drawn from this set)
Next: revisit topics where your reasoning is still uncertain, then compare the full app’s study features. Free demo and full app
How to use this test
Time yourself at about 1.8 minutes per question, the pace of the real exam (240 minutes for 135 questions). Read the explanation for every wrong choice, then repeat the work area where you missed the most.
Questions about the exam
How many questions are on the Machinist Red Seal exam (Ontario 429A)?
135 multiple-choice questions in four hours, with a 70% pass mark. Each question has four choices and one correct answer, according to the Red Seal exam preparation guide. In Ontario the trade code is 429A.
How long do I have per question?
About 1.8 minutes. The official guide suggests dividing 240 minutes by the number of questions on your exam; 135 questions gives about 1.8 minutes each. Practise at that pace on full mocks.
What score do I need to pass?
70%. The Red Seal exam preparation guide states a 70% pass mark and a four-hour writing time. Confirm the details for your sitting on your exam confirmation.
Where can I get more practice questions?
Start with the free sample questions and self-assessment for your trade on red-seal.ca. For more volume, the Machinist Red Seal Exam Prep app has 1,500+ original questions in English and French; the download is free with 50 questions, and one C$19.99 purchase unlocks the rest.
Are these real Red Seal exam questions?
No. They are original questions written to the published exam breakdown. Official exam questions are not published, and the Red Seal Program says it does not endorse any test preparation company or website.
Sources and next study steps
Revisit the topics where you hesitated. Compare your method with the references, then explain the units and each step without looking at the solution.
How these resources are checked
These independent resources are written and reviewed with AI assistance. Public questions come only from the approved demo samples. Automated tests check option, answer and explanation associations in both languages; numerical tests check the worked calculations. Official sources support the exam information. These checks are not a technical review by a qualified tradesperson.
Found an error or ambiguous wording? Include the trade, language and question number in your message. Report a content issue
Free demo, full app and official study resources
Choose the resources that fit your next study session. The demo and app are independent study aids; use official sources for exam rules.
Try it free
25 reviewed bilingual questions for your trade, with answers and explanations, in your browser. No account. A timed 10-question demo drawn from the same set is also available.
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Check the official exam basis
Read the exam breakdown and Red Seal Program resources free of charge. Your provincial or territorial authority determines eligibility and registration.
Official exam informationIndependent study aid by Certloom Learning. Not affiliated with or endorsed by the Red Seal Program. No passing guarantee.