Machining & Threading Tools.

What are Machining & Threading Tools?

Machining and threading tools, also called thread cutting tools, are the taps, dies and holders in Accu's Screwdrivers, Drive Bits & Hand Tools range, covering every stage of cutting a screw thread from production tapping on a CNC machine to repairing a damaged stud at the bench. A tap is a hardened, fluted cutter with a threaded body and a square or 1/4" hex drive, while a die is a ring or hexagon of hardened steel with cutting teeth around its bore; the tap wrenches and die stocks that drive them by hand are steel handles with a chuck or die cavity at the centre. Used together, they cut a mating thread to a defined form, pitch and tolerance class, so a screw, stud or fitting engages fully in the part it was designed for.

Thread cutting tools are made to recognised tolerance classes, such as 6H or 2B for internal threads and 6g or 2A for external ones, so the finished thread accepts its standard mating part without slack or binding. Taps and dies like these are used wherever parts are threaded in-house, from production machining in the automotive, aerospace and robotics sectors to maintenance teams chasing and repairing threads on installed plant.

How Machining & Threading Tools Work.

Taps and dies cut threads in the same way, from opposite sides of the joint. A tap's chamfered lead engages the wall of a pre-drilled hole gradually, each cutting edge removing a little more material until the full thread form is reached, while a die's lead chamfer does the same on the end of a bar or stud. On a machine, the spindle controls speed and feed while the flute geometry manages the chips: spiral point taps push swarf ahead through open holes and spiral flute taps lift it out of blind ones. By hand, a tap wrench or die stock holds the tool square and supplies the leverage, with a short reverse turn after each advance to break the chip.

For example, a manufacturer building robot arms for automated packing lines uses spiral flute machine taps on a CNC machine to tap the M6 holes that hold each joint motor in place, giving every aluminium housing the same accurate thread. If one of those threads is damaged during assembly, an engineer can recut it at the bench with a hand tap and tap wrench instead of scrapping a finished housing. External threads work the same way, with a die held in a die stock cutting a fresh thread on the end of a steel rod that supports the arm's safety guard. Without these tools, a single damaged thread could hold up the whole build.

Materials Machining & Threading Tools Are Made From

Accu's machining and threading tools are made from engineering-grade tool materials, each chosen for the edge hardness, heat resistance and toughness the job demands:

• Steel - HSS: General-purpose high speed steel for cost-effective threading in mild steel, aluminium and brass, used for every hand tap, the Wera Combination Drill & Tap Bits and most dies.
• Steel - HSS-E: Cobalt-enhanced high speed steel with improved heat and wear resistance for tapping stainless steels and harder alloys, used for most machine taps and selected dies.
• Steel - HSS-PM: Powder metallurgy high speed steel, giving greater toughness and longer tool life than conventional HSS under demanding cutting conditions.
• Steel - HSS-PM1: A powder metallurgy grade with greater toughness than conventional HSS, for tapping alloy and tool steels.
• Steel - HSS-PM3: A powder metallurgy grade with high toughness and edge retention, for demanding tapping in hardened steel, stainless steel and titanium alloys.
• Steel - HSS-V3: High-vanadium high speed steel with high wear resistance in abrasive or work-hardening materials.
• Carbide: Considerably harder and more rigid than high speed steel, suiting hardened steels where HSS wears quickly.
• Steel: Used for the hand tap wrenches, die stocks and Wera Hand Tap Bits, giving holders the rigidity to transmit threading torque without flexing.

Machine taps are supplied Bright or with a surface coating matched to the workpiece, such as TiN Coated for general-purpose tapping in steel and stainless steel, TiCN Coated for abrasive materials, TiAlN Coated for hardened steels and CrN Coated for aluminium and other non-ferrous metals.

Sizes & Types of Machining & Threading Tools Available

Accu's machining and threading tools are available in seven types, covering internal and external threads by machine and by hand:

• Machine Taps: Metric Coarse from M2 to M52 and Metric Fine from M4 to M36, plus UNC (Unified Coarse) from No. 4 to 1-1/8" and UNF (Unified Fine) from No. 4 to 1", with Spiral Flute, Spiral Point and Straight Flute geometries for Blind Holes, Through Holes or both.
• Hand Taps: M1.6 to M60 across ten thread specifications, including BSW, BSF, BA, BSP(G), BSPT and NPT, sold as individual First, Second and Bottom taps or as sets.
• Wera Combination Drill & Tap Bits: M3 to M10, each drilling the pilot hole, cutting the thread and deburring in one operation from a 1/4" hex drive.
• Wera Hand Tap Bits: M3 to M10 taps on a 1/4" hex drive, for threading pre-drilled holes from a standard bit holder.
• Dies & Die Nuts: M1 to M56 metric and BSP(G) up to 4", alongside UNC, UNF, BSW, BSF, BA, NPT and NPTF, in Circular Split, Circular Solid, Circular Solid Bell Form and Hexagonal geometries.
• Hand Tap Wrenches: Bar and Ratchet types for hand taps up to M38 (1-1/2"), across seven wrench sizes.
• Die Stocks: BS 1127 stocks for circular split dies from 13/16" to 4" in diameter and DIN 223 stocks for circular solid dies from 20 mm to 55 mm.

Not every combination exists. Pipe threads (BSP(G), BSPT and NPT) are cut with hand taps and dies only, and left-hand taps are only available as machine taps. Carbide machine taps are limited to straight flute Metric Coarse sizes from M3 to M20, while both Wera ranges stop at M10 and cover metric threads only. Die stocks are not interchangeable either: BS 1127 stocks take circular split dies sized in inches and DIN 223 stocks take solid dies sized in millimetres, so match the stock to the die's outside diameter rather than the thread it cuts.

Accu's Precision Screws and Threaded Rods supply the mating parts for the threads these tools cut. For assemblies where a separately cut thread is not essential, why not browse Accu's range of Thread Forming Screws, which form their own mating thread as they are driven into a plain pilot hole.

FAQ

Q: What is the difference between a tap and a die?

A: A tap cuts an internal thread inside a pre-drilled hole, while a die cuts an external thread on the outside of a bar, rod or stud. Used at the same thread specification, they produce both halves of a mating pair, which is why taps and dies are usually specified together.

Q: Should I use a machine tap or a hand tap?

A: Use a machine tap on a CNC machine, drill press or lathe, where the spindle controls speed and feed and the flute geometry is matched to the hole type, which suits repeat production. Use a hand tap in a tap wrench for prototypes, repairs and parts that cannot go back on the machine; working through First, Second and Bottom taps spreads the cutting load so each stage needs less torque.

Q: Which tap should I use for a blind hole?

A: On a machine, choose a spiral flute tap, whose helical flutes lift chips out of the hole so they do not pack at the bottom; spiral point taps push chips forward and suit through holes. By hand, start with a First tap and finish with a Bottom tap, whose short lead carries the full thread close to the bottom of the hole. Either way, drill deeper than the thread length you need to leave room for chips and the tap's lead.

Q: What size hole should I drill before tapping?

A: It depends on the thread's diameter and pitch. For metric threads, a reliable rule of thumb is nominal diameter minus pitch, so M8 x 1.25 needs a 6.8 mm hole. Confirm the figure in Accu's tapping drill size chart before drilling: too small risks a broken tap, too large leaves a shallow, weak thread. For M3 to M10, the Wera Combination Drill & Tap Bits drill the correct pilot hole as part of the same operation.

Bespoke Machining & Threading Tools Manufacture.

High precision, bespoke manufacture of Machining & Threading Tools to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.