Machinist safety, drawings and materials practice questions (429A).

Five free practice questions on safety, drawings and materials: block A of the Red Seal 429A Machinist exam, about 13 of its 135 questions. They are in the exam's format: four options, one correct answer. Answer each one before opening the explanation. No account, no email.

01The questions

1. Recall · Uses personal protective equipment (PPE) and safety equipment

   A new degreaser arrives with its SDS. Which section of the SDS gives the gloves, eye protection and respirator needed to work with it?

   1. Section 11.
   2. Section 8.
   3. Section 2.
   4. Section 7.
   Show the answer

   B. Correct. Section 8, exposure controls and personal protection, gives exposure limits, engineering controls and the specific PPE: glove material, eye and face protection and respiratory protection. Every WHMIS SDS uses the same 16 sections in the same order, so it is always section 8.

   Why not the others

   A. Section 11, toxicological information, describes routes of exposure and health effects. It explains why protection matters, but the protective equipment itself is listed in section 8.

   C. Section 2, hazard identification, gives the hazard classes, signal word, pictograms and hazard statements. It says what the product can do; the PPE to wear is listed in section 8.

   D. Section 7, handling and storage, covers safe handling practice and storage conditions such as incompatible materials. The specific gloves, eye protection and respirator are listed in section 8.

2. Procedural · Interprets documentation

   A surface-texture symbol on the flat end face of a round part carries the lay symbol C. Which operation leaves that lay?

   1. Shaping across the face.
   2. Lapping on a flat plate.
   3. Facing on a lathe.
   4. Traverse surface grinding.
   Show the answer

   C. Correct. Lay symbol C means the tool marks run roughly in circles about the centre of the surface. Facing on a lathe leaves a fine spiral of concentric marks, which is exactly that pattern.

   Why not the others

   A. A shaper's tool cuts in straight strokes, leaving parallel lay marks. Circular marks centred on the face, lay symbol C, come from facing on a lathe.

   B. Lapping on a plate moves the work in changing directions and leaves a multidirectional lay, symbol M. Circular lay, symbol C, comes from facing on a lathe.

   D. A surface grinder leaves straight, parallel scratches in the direction of table travel, which takes the parallel or perpendicular lay symbol. C calls for circular marks, as from facing on a lathe.

3. Procedural · Uses communication techniques

   A journeyperson has explained a new fixture set-up to an apprentice. Which check best confirms that the apprentice understood it?

   1. Ask the apprentice whether it all made sense.
   2. Go over the explanation once more, but more slowly.
   3. Have the apprentice explain the steps back in order.
   4. Give the apprentice a printed copy of the set-up sheet.
   Show the answer

   C. Correct. Asking for the steps back in the apprentice's own words shows what was actually understood and exposes gaps while they are easy to fix. Putting it into words also helps the sequence stick.

   Why not the others

   A. A yes-or-no question invites a polite yes, even from an apprentice who is lost. Ask an open question instead, such as having the apprentice walk through the steps in order.

   B. Repeating the explanation assumes where the gap is without checking. Have the apprentice explain the steps back first, then re-teach only what was missed.

   D. A set-up sheet is useful to keep, but handing it over does not show whether the explanation was understood. Have the apprentice explain the steps back.

4. Procedural · Performs quality control of workpiece

   The hardness of a grey cast iron housing must be checked against the drawing. Which test suits its coarse structure best?

   1. File test, graded file set.
   2. Brinell, 10 mm ball.
   3. Rockwell B, 1/16 in. ball.
   4. Rockwell C, diamond cone.
   Show the answer

   B. Correct. The Brinell test presses a 10 mm ball into the work, leaving a large impression that averages the iron matrix and the graphite flakes. That is why cast iron hardness is usually specified in Brinell (HB).

   Why not the others

   A. Graded files give only a rough bracket of hardness and no number to compare with the drawing. A Brinell test gives a measured value.

   C. Rockwell B, a 1/16 in. ball at 100 kgf, suits softer steels and non-ferrous metals, but its small indent is affected by individual graphite flakes. The large Brinell impression gives a representative average.

   D. Rockwell C uses a diamond cone at 150 kgf and is meant for hardened steel. Grey iron sits at or below the bottom of its useful range, and the small indent lands on individual flakes and matrix, so readings scatter.

5. Procedural · Sharpens tooling

   A pedestal grinder wheel has just been dressed, and the grinder is stopped. What must be done before grinding resumes?

   1. Close the work rest and tongue guard up to the wheel.
   2. Ring test the wheel again before it is restarted.
   3. Re-tighten the flange nut before the wheel is restarted.
   4. Lower the speed to suit the smaller wheel diameter.
   Show the answer

   A. Correct. Dressing removes abrasive and reduces the wheel diameter, opening both gaps. A wide work-rest gap lets the work be dragged in and jammed between rest and wheel. With the grinder stopped, reset both within the limits that apply; CCOHS guidance gives 3 mm (1/8 in.) at the work rest and 6 mm (1/4 in.) at the tongue guard.

   Why not the others

   B. The ring test checks a wheel for cracks before it is mounted. Dressing does not call for another one; what dressing changes is the gap at the work rest and tongue guard, which must be reset.

   C. Dressing does not loosen the flanges, and over-tightening the nut can crack the wheel; it is tightened only enough to drive the wheel. What dressing changes is the clearance at the rest and tongue guard.

   D. A smaller wheel at the same rpm runs at a lower surface speed, so the speed marked on the wheel is not exceeded. What dressing changes is the gap at the work rest and tongue guard.

02Answer key

03What block A covers

Block A is the shop knowledge behind every job: working safely and using PPE, reading drawings and tolerances, planning the sequence of operations, talking a job through with co-workers and apprentices, choosing and handling workpiece material, heat treatment, quality control and deburring, and keeping machines, tooling and inspection equipment in good order. Hoisting, lifting and rigging sits here too.

The Red Seal Occupational Standard names this block “Performs common occupational skills”. It carries 9.6% of the exam, about 13 of the 135 questions, split across five tasks. The share column is each task's weight within the block, as the standard publishes it.

04What the questions turn on

Machine soft, harden, then grind

For a hardened part with a tight tolerance, the bulk of the metal comes off while the steel is soft, leaving a grinding allowance. Hardening distorts and scales the part, tempering follows at once, and grinding last brings it to size.

An H bore starts at nominal

On a fit callout such as H7, the capital H marks a hole whose lower deviation is zero. The smallest acceptable bore is the nominal size, and the whole tolerance from the fit table lies above it.

A tilted test lift means re-rig

A suspended load settles with its centre of gravity directly under the hook. If a test lift hangs tilted, land the load, move the attachment points or adjust the leg lengths, and repeat the test lift.

Conflicting dimensions go to the owner

When a drawing gives one feature two different sizes, only the person who controls the drawing can say which is right. Get the answer before cutting, ideally as a written note or a revised drawing.

05The other blocks

The 429A exam has eight blocks. Each has its own page of free questions:

The 429A Machinist practice exam page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.