Metalworking tools: names, pictures and what each one is used for

Measure, mark, then cut, in that order

Metal does not forgive. A cut in the wrong place cannot be glued back or filled, and a hole drilled off centre stays off centre. So the discipline is that measuring and marking out are a stage of the work rather than a preliminary to it.

This is also why metalworkers scribe rather than pencil. A scribed line is a fine permanent scratch you can cut precisely to, where a pencil line is wide, vague and rubs off. On a dark or shiny surface, layout fluid is painted on first so the scribed line shows as bright metal.

And a hole is always centre punched before drilling. Without that dent the drill bit skates across the surface and starts its own hole somewhere near where you wanted it.

Scribe, do not pencil

A scribed line is fine and permanent, so you can cut exactly to it. Pencil is too wide to work from.

Layout fluid on shiny metal

Blue marking fluid makes a scribed line show as bright metal. Without it you cannot see your own marks.

Centre punch before every hole

The dent gives the drill somewhere to start. Skip it and the bit wanders and the hole ends up off position.

Work from one datum edge

Measure everything from the same edge and face. Chains of measurements accumulate error that cannot be undone.

Check with a square, not by eye

Metal offers no grain or shadow to judge by. If it needs to be square, a square tells you and your eye does not.

Deburr before measuring

A burr on the edge holds a caliper jaw off the surface, so every reading from that edge is a fraction over.

Speed, feed and cutting fluid

The single most common reason a drill bit, tap or cutter fails is running it too fast. Metal cutting generates heat at the cutting edge, and above a certain temperature the tool loses its hardness permanently. Once that happens no amount of pressure will make it cut again.

The general rule is opposite to what feels natural: harder material and larger diameter both mean slower speed. A large hole in stainless wants a very slow drill and firm steady pressure. A small hole in aluminium can run fast.

Cutting fluid is the other half. It carries heat away and lubricates the edge, and it makes a visible difference to both finish and tool life. Working dry is what wears tools out.

Slower for harder and bigger

Stainless and large diameters want low speed. High speed in tough material burns the edge off in seconds.

Steady firm pressure, not fast

A bit that is rubbing rather than cutting generates heat and work hardens the surface, and then it will not cut at all.

Use cutting fluid

It cools and lubricates. It transforms tool life and surface finish, and it costs very little.

Watch the chips

Good curled chips mean it is cutting. Dust, blue chips or a squeal mean stop and change something.

Peck deep holes

Withdraw to clear the chips. A packed flute stops cutting, overheats and snaps the bit in the hole.

Never let a tap bind

Turn forward, then back to break the chip. Forcing a bound tap snaps it off inside the hole, which is very hard to remove.

Holding the work is half the job

Almost every accident and most bad results in metalwork come from work that moved. Metal is heavy, slippery and sharp, and a drill bit grabbing a loose piece of sheet turns it into a spinning blade.

So the rule is that the work is clamped, not held. This is not caution for its own sake: a piece held by hand cannot be cut accurately either, because it moves under the tool and the cut wanders.

The corollary is that vices, clamps and jigs are not accessories. On a drill press or a mill they are what makes the machine capable of accuracy at all.

Clamp it, never hold it

Especially thin sheet on a drill press, where a grab spins the piece into a blade at hand height.

Soft jaws on finished surfaces

A vice with hardened serrated jaws prints those serrations permanently into anything soft or finished.

Support the far side when drilling

A bit breaking through unsupported material grabs, tears and distorts the exit hole.

Use a machine vice on a drill press

Bolted down, so a grab cannot spin the vice as well. A hand held vice is no better than a hand.

Stop the machine to clear chips

Never with fingers or a rag while it turns. Hot swarf is sharp, and a rag caught in a cutter takes the hand with it.

No gloves near rotating machinery

A caught glove pulls the hand in. Gloves for handling stock, off for the machine.

What to buy first, in order

Stage one: marking out and hand cutting

A steel rule, an engineer's square, a scriber, a centre punch, layout fluid, dividers, a hacksaw, a file set with a file card and a bench vice.

Stage two: measuring and drilling

Vernier or digital calipers, a set of HSS drill bits, a countersink, a deburring tool, cutting fluid, and a drill press with a machine vice.

Stage three: threading and shaping

A tap and die set with a wrench and holder, a thread gauge, a reamer set, tin snips, a cold chisel and an angle grinder.

Stage four: machines

A metal cutting bandsaw, a bench grinder, a lathe, then a mill. Each is a large step in capability and in cost.

Mistakes that ruin work or tools

Drilling too fast

The most common fault. It burns the edge off the bit permanently and work hardens the surface so nothing else will cut it.

No centre punch

The bit skates and starts a hole where it likes. Position error you cannot correct afterwards.

Forcing a tap that has bound

It snaps off inside the hole. Extracting a broken tap is one of the worst jobs in the shop.

Working dry

Heat destroys cutting edges and spoils the finish. Cutting fluid is cheap and it doubles tool life.

Holding sheet metal by hand to drill it

It grabs and spins into a blade. This is the classic serious injury in a home metal shop.

Using a file without a handle

The bare tang goes through a palm if the file catches. A handle costs almost nothing.

Measuring over a burr

The caliper jaw sits on the burr rather than the surface, so every reading from that edge is over.

Serrated vice jaws on a finished part

They print into the surface permanently. Soft jaws or packing, on anything that will be seen.

Looking after metalworking tools

Brush files with a file card

A clogged file burnishes instead of cutting, and the trapped metal scratches the next piece.

Never store precision instruments loose

Calipers and micrometers in a drawer with files come out inaccurate. Cases, always.

Oil bare steel

Machined surfaces rust overnight in a damp shop, and a rusty machine table marks everything on it.

Dip when grinding, do not let it colour

If the steel turns blue on a grinder, the temper is gone at that spot and the edge is soft forever.

Zero and check measuring tools

Close a caliper and confirm it reads zero. An instrument you have not checked is a guess with a decimal point.

Clear swarf off machines every time

Swarf holds coolant against the metal and rusts a table, and it gets into slides and ways where it does real damage.

Frequently asked questions

What metalworking tools do I need to start?

A bench vice, a steel rule, an engineer's square, a scriber, a centre punch, layout fluid, a hacksaw, a file set and calipers. Add a drill press with a machine vice and a tap and die set, and you can make a great deal.

What is the difference between metalworking and blacksmithing?

Metalworking here means working metal cold, by cutting, filing, drilling, turning and milling to a measured dimension. Blacksmithing works it hot, moving and shaping it under a hammer. The toolkits barely overlap.

Why do I keep breaking drill bits in metal?

Almost always too much speed, not enough pressure, no cutting fluid, or a packed flute in a deep hole. Slower speed with firm steady feed and fluid is the answer, and withdraw regularly to clear the chips.

What is layout fluid and do I need it?

A blue dye painted onto metal so a scribed line shows as bright metal against it. On any shiny or dark surface you genuinely cannot see your own marks without it, so yes for accurate work.

Why must I centre punch before drilling?

The dent gives the drill point somewhere to start. Without it, the bit skates across the surface and begins its own hole wherever it happens to bite, and that position error cannot be corrected later.

What is the difference between a tap and a die?

A tap cuts an internal thread inside a drilled hole. A die cuts an external thread onto a rod or bar. Taps come in sets of taper, second and plug for starting, continuing and reaching the bottom of a hole.

Why did my tap snap in the hole?

It bound and was forced. Taps cut a chip that has to be broken by turning back a quarter turn every half turn or so, and the tapping hole must be the right size. A snapped tap is hardened steel and very hard to remove.

What size hole do I drill before tapping?

The tapping drill size for that thread, which is smaller than the thread diameter and listed on any tapping chart or on the set itself. Too large and the thread has no depth, too small and the tap binds and snaps.

What is the difference between a reamer and a drill?

A drill makes a hole roughly to size. A reamer follows it and brings it to an exact diameter with a good surface finish. Anything that needs a precise fit, like a dowel or a bearing, is drilled undersize then reamed.

Do I need cutting fluid?

For anything beyond the occasional hole, yes. It carries heat away from the cutting edge and lubricates it, which markedly improves both tool life and surface finish. Working dry is the main reason tools wear out early.

What is the difference between a lathe and a mill?

On a lathe the work rotates and the tool moves, producing round parts. On a mill the cutter rotates and the work moves, producing flat faces, slots and pockets. They are complementary rather than alternatives.

Why should I not wear gloves at a machine?

Because a glove caught by a rotating cutter or chuck pulls your hand in with it, where bare skin would tear free. Wear gloves to handle sharp stock, and take them off before starting the machine.