Five free practice questions on benchwork and hand tools: block B of the Red Seal 429A Machinist exam, about 11 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
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A hand reamer turned with a tap wrench becomes tight partway through a 10 mm hole in steel. What should be done?
- Turn it backward a quarter turn to free it.
- Keep turning it forward while lifting it out.
- Pull it straight out without turning it.
- Press down harder until it passes the tight spot.
Show the answer
B. Correct. Turning a reamer forward keeps the chips ahead of the cutting edges. Lift it out while still turning forward, clear the chips, add cutting fluid and continue.
Why not the others
A. Reversing a reamer drags chips back between the cutting edges and the bore, chipping the edges and scoring the hole. A reamer is turned forward only, going in and coming out.
C. Pulling it out without turning drags the cutting edges and trapped chips up the finished wall and scores it. Keep it turning forward as it comes out.
D. A hand reamer is fed with light, even pressure. Forcing it past a tight spot can chip the edges or tear the bore, leaving it oversize or out of round.
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A keyway is being broached in a 25 mm hub bore with a bushing and an arbor press. The first pass is complete. What is done before the second pass?
- Push the broach back through from below.
- Add a shim behind the broach in the slot.
- Change to the next larger size of bushing.
- Turn the bushing half a turn in the bore.
Show the answer
B. Correct. The shim goes in the bushing slot behind the broach and moves its teeth deeper into the bore for the next pass. Shims are added pass by pass as the set directs until the keyway reaches depth.
Why not the others
A. Broach teeth cut in one direction only. Pushing it back against the teeth jams it, chips the teeth and spoils the keyway; each pass is a fresh push in the cutting direction.
C. The bushing is sized to the bore, 25 mm here, so it locates the broach on the bore's axis. A larger one will not fit; depth comes from shims.
D. Turning the bushing puts the broach on the opposite side of the bore and starts a second keyway. The bushing stays put; shims move the broach outward to deepen the same cut.
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What is the bend allowance for a 90° bend in 4 mm plate with a 10 mm inside radius, to two decimal places?
- 36.44 mm
- 21.99 mm
- 15.71 mm
- 18.22 mm
Show the answer
D. Correct. Bend allowance = (r + 0.4T) × 1.5708 = (10 + 0.4 × 4) × 1.5708 = 11.6 × 1.5708 = 18.22 mm. It is the length of the neutral axis through the bend, added to the straight legs to give the blank length.
Why not the others
A. This multiplies by 3.1416, which gives a 180° bend. For a 90° bend the arc is a quarter circle, so the factor is π ÷ 2 = 1.5708.
B. This uses the outside radius, (10 + 4) × 1.5708. The metal at the outside surface stretches; the length that stays the same is the neutral axis at r + 0.4T.
C. This is 10 × 1.5708, the inside radius alone. The neutral axis lies 0.4 of the thickness in from the inside of the bend, so 0.4 × 4 = 1.6 mm is added to the radius first.
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Why are the caps of a split bearing housing punch-marked to their bases before they are removed?
- Each mark shows how far the bolts were turned.
- Each mark flags a cap due for replacement.
- Each cap was line-bored with its own base.
- Each mark records the bearing's clearance.
Show the answer
C. Correct. The cap and base were machined together as one bore, so a cap fits correctly only on its own base and the same way round. Swapped or reversed, the bore is stepped or out of round and pinches the bearing.
Why not the others
A. Punch marks on a cap and base identify position, not bolt tightness. Bolts are tightened to the torque in the documentation on reassembly.
B. Replacement is decided after cleaning and measuring, and is recorded in the inspection notes. The punch marks match each cap to its own base and orientation.
D. Clearance is measured and written down during inspection; a punch mark cannot record it. The marks keep each cap with the base it was bored with.
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A gearbox cover is held by six bolts with a specified torque of 40 N·m (30 lb-ft). How are they tightened?
- Criss-cross in one pass to 44 N·m for settling.
- Criss-cross in two or three steps to 40 N·m.
- Each to 40 N·m in turn around the circle.
- Opposite pairs, each pair to 40 N·m at once.
Show the answer
B. Correct. Tightening across the pattern in stages pulls the cover down evenly so it seats flat on its gasket or face. The final pass at 40 N·m (30 lb-ft) brings every bolt to the specified torque.
Why not the others
A. The specified torque is the clamping load the joint is designed for; going 10 % over loads the bolts past their design preload and can crush the gasket or strip threads. Tighten to the specified 40 N·m in stages.
C. Taking one bolt to full torque before the next pulls one side down first and can cock the cover, leaving the last bolts closing a gap. Torque in stages across the pattern.
D. Each bolt goes to full torque in one step, so the first pair clamps the cover before the others are snug and it may not seat evenly. Bring all the bolts up in stages.
02Answer key
| Question | Answer | Sub-task |
|---|---|---|
| Q1 | B | Performs hole making operations |
| Q2 | B | Broaches workpiece |
| Q3 | D | Forms workpiece |
| Q4 | C | Disassembles components |
| Q5 | B | Assembles components |
03What block B covers
Block B is the work done at the bench with hand tools: layout, hacksawing, filing, drilling and reaming by hand, cutting threads with taps and dies, installing thread inserts, broaching keyways, pressing and forming, and hand finishing such as scraping. It also covers refurbishing components: taking assemblies apart, analyzing the parts and putting them back together.
The Red Seal Occupational Standard names this block “Performs benchwork”. It carries 8.1% of the exam, about 11 of the 135 questions, split across two tasks. The share column is each task's weight within the block, as the standard publishes it.
| Task and its sub-tasks | Share of block |
|---|---|
| Performs hand processes Performs layout; Saws workpiece; Files workpiece; Performs hole making operations; Performs threading operations; Installs thread inserts; Broaches workpiece; Performs pressing operations; Forms workpiece; Finishes workpiece | 69% |
| Refurbishes components Disassembles components; Analyzes components; Assembles components | 31% |
04What the questions turn on
Reading a go/no-go thread gauge
The no-go member of a thread plug gauge is made to the largest pitch diameter allowed. If it screws in full depth along with the go member, the tapped thread is oversize and the part fails.
Bottoming taps finish, not start
A bottoming tap has only one or two chamfered threads, so nothing leads it in square and the first full threads take a heavy cut. Start the hole with a taper or plug tap and finish near the bottom with the bottoming tap.
Pull on the fitted ring
The puller bears on the ring that carries the interference fit. For a bearing pressed on its shaft that is the inner ring. Pulling on the outer ring sends the load through the balls and dents the raceways.
Insert taps are oversize, same pitch
A helical-coil insert winds into a special oversize thread that keeps the pitch of the bolt it repairs. The tap supplied for that insert cuts it, and the installed insert leaves a standard thread for the original bolt.
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.