Taps, Dies, and Screw Extractors

A tap cuts internal threads inside a drilled hole. A die cuts external threads on a round rod. A screw extractor backs out a fastener that’s stripped, snapped, or seized. Three different jobs, three different tools — and buying the wrong one is how a small repair turns into a bigger one.

The whole game is matching the tool to the exact fastener: thread type, diameter, pitch, and the correct drill bit size. Get those numbers right before you cut or extract anything, and the rest is technique. Get them wrong, and you’re drilling out the mess you just made.

Tap and die tools are commonly made from high-carbon steel (HCS) for hand threading, with self-aligning plug and taper taps, fractional, metric, and machine dies, plus offset, T-handle, ratcheting, and adjustable tap and reamer wrenches in the lineup. HSS (high-speed steel) comes into play for machine tapping where critical dimensions matter. For hand work at the bench or on the truck, HCS does the job.

Picking the Right Tap, Die, or Extractor

Taps cut threads inside holes. Three chamfer styles cover most situations, and the difference is how many threads are tapered at the tip:

• Taper tap — 8 to 10 threads chamfered. The long lead-in makes it the easiest to start straight and the right choice for tough materials or threading all the way through a hole.
• Plug tap — 3 to 5 threads chamfered. The most common general-purpose tap. Starts reasonably easy, threads most of the way down.
• Bottoming tap — 1 to 2 threads chamfered. For running threads down close to the bottom of a blind hole where there’s nowhere for chips to go.

Self-aligning taps start straight every time, which matters when you can’t eyeball perpendicular. Western Building Center carries a plug tap selection in coarse sizes — 8-32, 10-24, 1/4-20, 5/16-18, and 3/8-16 in NC — along with a 10mm-1.25 metric plug tap and pipe taps in 1/4-18 NPT and 1/2-14 NPT.

Dies cut threads on rods. Used the same way in reverse — running external threads onto round stock or chasing damaged threads back to clean. The stock list includes a 1/2-13NC hex die and an 8mm-1.25 metric hex die.

Extractors remove broken fasteners. These are the solution for stuck, rounded, snapped, stripped, or broken-head fasteners, and the family includes straight-flute and hex-head multi-spline styles. The extractor bites into a pilot hole you drill into the dead fastener, then backs it out as you turn counterclockwise.

Reading the Size Designation

Every thread size tells you three things. Take 10-24 NC: the 10 is the diameter (a #10 machine screw), the 24 is the pitch (24 threads per inch), and NC is the thread type. Sort those three out and you can match any fastener.

Thread types you’ll run into:

Type	What it means
NC (UNC)	National Coarse / USS
NF (UNF)	National Fine / SAE
NS	National Special
NEF	National Extra Fine
NPT	Tapered pipe thread
BSP	British Standard Pipe
Metric	Diameter × pitch in mm (e.g. 10mm-1.25)

The tap size and the recommended drill bit size are laser-etched right on the tool. Before tapping a fresh hole, a tap/drill chart tells you the exact bit to drill first — too big and the threads won’t hold, too small and you’ll break the tap.

That’s why the combo packs are worth a look. Western Building Center stocks tap-and-drill sets that pair the tap with its matching bit — 8-32, 10-24, 1/4-20, 1/4-28, and 1/2-13. No guessing, no chart needed for those sizes.

Sizing and Using a Screw Extractor

Extracting a broken bolt is a high-stakes job. The reference chart matches both the drill bit and the extractor size to the damaged fastener — for example, a 3/8” (10mm) bolt calls for a 3/16” drill bit paired with a #2 straight extractor. Drill the pilot too large and there’s nothing left for the extractor to grab.

Western Building Center carries individual extractors — #2, #4, #5, and #6 — plus a 5-piece set covering sizes 1 through 5. There are also extractor-and-bit combos (#1, #2, #5) that pair each extractor with the correct pilot drill, which takes the chart math out of the equation on the common sizes.

Technique That Saves the Workpiece

The procedure protects both the part and the tool:

• Keep the tap perpendicular to the hole. Press down and turn — straight in, no wobble.
• After 2 to 3 full turns, back the tap off a half to three-quarter turn to break the chip loose. Skip this and the chip packs up and snaps the tap.
• Always use a quality cutting fluid. It extends tool life and gives you a cleaner thread.

You’ll want a proper wrench, not pliers. The HANSON tap wrench lineup includes T-handle versions (TR-1E, TR-2E), the TR-88 adjustable tap and reamer wrench, the TR-73 with 3/8” drive, offset handles, and ratcheting models. T-handles give you fine feel for small taps; the adjustable tap/reamer wrenches handle a wider range. Western Building Center stocks the TR2E T-handle and the TR88 tap/reamer wrench.

Frequently Asked Questions

What’s the difference between a tap and a die? A tap cuts internal threads — the female threads inside a drilled hole, like the threads in a nut. A die cuts external threads — the male threads on a rod or bolt. Both also chase and clean up damaged existing threads.

Which tap should I use for a blind hole? A bottoming tap, which has only 1 to 2 threads chamfered, runs threads down close to the bottom of a hole that doesn’t go all the way through. Many people start the hole with a taper or plug tap, then finish with the bottoming tap to get full threads near the bottom.

How do I know what drill bit size to use before tapping? Use a tap/drill chart to find the correct bit for your thread size, or read the recommended drill size laser-etched on the tap itself. Combo tap-and-drill sets remove the guesswork by pairing the tap with its matching bit.

What drill bit and extractor size do I need for a broken 3/8” bolt? For a 3/8” (10mm) bolt, the reference chart calls for a 3/16” drill bit with a #2 straight extractor. Always check the chart for your specific fastener rather than guessing — an oversized pilot hole leaves nothing for the extractor to grip.

Do I really need cutting fluid? Yes. Cutting fluid extends the life of the tap or die and produces a cleaner, stronger thread. Running a tap dry generates heat and friction that dull the tool and tear the threads.

What does 10-24 NC mean? Three pieces of information: 10 is the diameter (a #10 machine screw), 24 is the pitch (24 threads per inch), and NC is the thread type — National Coarse. Every thread designation follows this diameter-pitch-type pattern.