Hand Tools
Hand Tools
This domain tests correct selection, safe use and maintenance of files, hacksaws, chisels, taps and dies, spanners, screwdrivers and pliers.
Core rules
- Files cut on the forward stroke. Match cut and grade to the job: rough files remove material, smooth files finish. Fit a handle and clean pins with a file card.
- Hacksaw blades are graded by teeth per inch. Use at least three teeth in contact with the work; thin tube and sheet need a fine blade (24–32 TPI), thick bar a coarser blade (14–18 TPI).
- Cold chisels have a hardened, tempered cutting edge around 60–70°; wood chisels are ground around 25–30°. Mushroomed heads must be ground off.
- Taps and dies cut internal and external threads. For metric coarse threads, tap drill diameter is approximately major diameter minus pitch.
- Spanners must fit the flats fully; adjustable wrenches are a compromise. Screwdrivers must match the slot or recess and must never be used as chisels or pry bars.
Worked example
For an M10 × 1.5 internal thread, tap drill size = 10 − 1.5 = 8.5 mm. Use an 8.5 mm drill, then taper, second and plug taps in sequence with cutting lubricant, reversing periodically to break chips. A 10 mm drill would leave no thread form.
Traps
Using a file without a handle; choosing a coarse blade for thin tube; using an oversized tap drill; turning a tap with pliers; using an open-ended spanner on a damaged nut.