Working metal without a machine shop
Metalworking is often pictured with welders and lathes, but a surprising amount can be done with hand tools: marking, cutting, drilling, filing and fitting small parts. Hand work is slower than machining, though it needs little space or power and teaches how metal behaves. This article describes tool types in general terms and is not professional trade advice. Metals vary widely in hardness and behavior, so follow the guidance for the material you are using.
1. Measuring and marking tools
Accuracy begins before any cutting. Useful tools include:
- A steel rule for measuring and as a straightedge.
- Calipers, either dial, digital or vernier types, for measuring thickness and diameters to a fraction of a millimeter or a few thousandths of an inch.
- A combination or engineer’s square to check right angles and mark lines.
- A scribe, a pointed tool that scratches a fine line into the surface.
- Layout fluid, or a marker, to make scribed lines easier to see.
Precision measuring tools only help when they are treated carefully. Keep them clean, avoid dropping them, and store them away from the rest of the bench. Cold metal and warm metal differ slightly in size, so for very precise work let the part reach a stable temperature.
2. Center punch and other punches
Before drilling, you mark the hole location with a center punch, tapped with a hammer, to make a small dimple. The drill bit settles into the dimple instead of skating across the surface. This small step improves the position of the hole considerably. When drilling metal, a pilot hole followed by larger bits, slow speeds and a little cutting oil are common practice, though the exact approach depends on the metal.
Other punches serve other jobs. A pin punch drives out pins and rivets, and a prick punch makes a lighter mark for layout. Striking tools should be used with a suitable hammer, usually a ball-peen hammer, and with eye protection. Punch heads that have mushroomed from repeated hits can shed fragments, so dress or replace them when you see that.
3. A hacksaw
A hacksaw is the basic hand saw for cutting metal. It consists of a frame holding a thin blade under tension. The key choice is tooth count, usually given as teeth per inch. As a general rule, thin material calls for finer teeth, so that several teeth are always in contact with the metal, while thicker stock works with coarser teeth. Blades are made in different steel types; harder blades stay sharp longer but can be more brittle.
Fit the blade with the teeth pointing away from the handle, so the saw cuts on the forward stroke, and tension it as the maker describes. Use long, steady strokes and ease off on the return stroke. Clamp the work in a vise close to the cut, since a loose workpiece can vibrate and break a blade. For other options when cutting metal, such as snips for sheet metal, the right tool depends on the thickness and shape of the material.
4. Files
Files remove small amounts of metal precisely, smooth edges and shape parts. They come in different lengths, shapes (flat, half-round, round, triangular) and cuts of tooth, from coarse to fine. A bastard cut is a common general-purpose grade, and finer second-cut and smooth files give a better finish.
A few habits extend a file’s life and improve the results:
- Fit a handle on the tang so the point cannot injure your hand.
- File on the forward stroke and lift slightly on the return.
- Clear clogged teeth with a file card or brush.
- Keep files dry and apart from one another, because files knocking together dull their teeth.
Filing is also part of metal deburring, which removes the sharp burrs left behind by sawing and drilling. Sharp burrs cause cuts and stop parts from fitting together, so removing them is a normal last step.
5. A bench vise
Metal needs to be held firmly in order to be cut, filed or drilled. A bench vise, bolted to a sturdy bench, holds the work at the right height and frees both hands. Look for a solid body, smooth jaw movement and jaws that line up. Soft jaw covers, made of aluminum or similar materials, protect finished surfaces from marks.
Position the work so that the cut or file is close to the jaws, which reduces vibration. For precision vise work, clean the jaws and avoid over-tightening thin pieces that may bend.
Safety around metal
Metalworking creates hazards that woodworking does not always share:
- Wear safety goggles or glasses. Chips, filings and shards can fly.
- Wear work gloves when handling sharp-edged stock, but not when using rotating equipment such as drills, where gloves can catch.
- Newly cut metal is sharp and may be hot. Handle it with care.
- Keep the bench clear and sweep up filings rather than brushing them off with bare hands.
Sharpening and maintaining tools matters too. High-speed steel drill bits, for example, can be resharpened, whereas files are generally replaced when dull. When in doubt about a material, such as galvanized steel or other coated metals, check safety information first, since filing, cutting or heating some coatings can release harmful dust or fumes.