28 Piece Metric Threading Kit for Workshop & Trade

A reliable internal thread starts before the tap ever touches the workpiece. The Sutton tap & drill set T901SDT1 gives workshops a matched approach to drilling & tapping seven commonly used metric thread sizes: M3, M4, M5, M6, M8, M10 & M12. The 28-piece set combines the tapping drills required to prepare each hole with taper, intermediate & bottoming taps for cutting the corresponding internal thread.

Rather than searching through loose drill bits & taps, you have a logical progression from preparation hole to finished thread. This makes the Sutton T901SDT1 particularly useful for fabrication, machinery maintenance, repairs, workshop projects & general engineering work where several metric thread sizes may be required across the same job.

For other drilling requirements, compare Sutton Tools | Drills - Jobber Coated or build out your workshop drilling setup with Drill Bit Sets.

What Is a Sutton Tap & Drill Set?

The Sutton T901SDT1 is a metric tap & drill set that brings together the preparation drill & three stages of straight-flute tapping for each included thread size. Rather than being an assortment of unrelated cutting tools, the set provides one tapping drill, one taper tap, one intermediate tap & one bottoming tap for every supplied metric thread.

The seven included sizes are M3, M4, M5, M6, M8, M10 & M12, with corresponding tapping drills ranging from 2.5 mm through to 10.2 mm. Four tools for each of the seven thread sizes gives you the complete 28-piece set.

That relationship between thread size & tapping-hole diameter is important because a tap isn't intended to correct a poorly prepared hole. The preparation drill determines how much material remains for the tap to cut, so choosing the required finished thread before drilling is an essential part of the process.

For threading requirements beyond the sizes supplied in this kit, Sutton Tools | Taps - JIS Uncoated provides another Sutton threading range to consider.

Why Choose a Sutton Tap & Drill Set?

One of the advantages of a matched tap & drill set is that the preparation tooling stays with the threading tooling. Instead of selecting a drill because its diameter appears close enough, the T901SDT1 supplies a corresponding tapping drill for each included metric thread size. This creates a much clearer sequence: establish the required thread, prepare the correct tapping hole, then cut the internal thread.

The three supplied tap stages also serve different purposes. A taper tap has a longer lead that introduces the cutting action progressively, while an intermediate tap uses a shorter lead to continue the thread. A bottoming tap has a shorter lead again, allowing full-form threads to continue closer to the bottom of a suitably prepared blind hole.

The set covers seven practical metric sizes from M3 through to M12, making it useful for fabrication, maintenance, repair & general workshop threading. Sutton also specifies the T901SDT1 for hand & machine operation, providing flexibility across different workshop setups.

Once the internal thread is complete, Bolts & Fasteners provides a logical next step when the component is ready for assembly.

Common Applications

Fabrication & Assembly

Fabricated brackets, guards, mounting plates, supports & custom components frequently require threaded holes. A tap & drill set keeps the preparation-hole drilling & metric threading stages together, making it easier to work methodically from the required fastener size through to the finished internal thread.

Machinery Maintenance & Repairs

Maintenance work can involve everything from replacing a damaged bracket to producing a new mounting point on existing equipment. Having M3, M4, M5, M6, M8, M10 & M12 tooling organised in one set gives workshops access to several useful metric sizes without relying on a collection of loose taps & drills.

Replacement Components

When reproducing an existing component, hole position deserves as much attention as thread quality. Before drilling, confirm the thread diameter, pitch, available depth & relationship to the mating component. Measuring & Layout Tools can help establish accurate hole positions before machining begins.

Jigs, Fixtures & Workshop Modifications

Stops, locating fixtures, machine plates & custom workshop accessories often rely on repeatable threaded holes. Accurate layout, correct tapping-hole preparation & controlled thread cutting all contribute to a component that fits the way it was intended.

General Engineering Work

Sutton specifies the T901SDT1 for general-purpose applications in suitable materials up to 1000 N/mm², with tapping depths up to approximately 1×d1. These specifications provide useful operating boundaries for this particular Sutton set, rather than universal instructions for every material or tapping operation.

Product Selection Guide

Start With the Finished Thread

Choose the required internal thread before selecting the drill. If the component requires an M6 thread, establish M6 first, then use the corresponding tapping drill supplied for that thread. Working in this order keeps the fastener, thread & preparation hole connected to the actual requirement of the finished component.

The T901SDT1 covers M3, M4, M5, M6, M8, M10 & M12. It does not contain every metric size between M3 & M12, so confirm that the thread required for the job is included before starting work.

Check Whether the Hole Is Blind or Through

A through hole exits the opposite side of the component, while a blind hole finishes inside the material. That distinction affects how the tapping operation should be planned, particularly when determining drilling depth.

With a blind hole, total drilled depth should not automatically be treated as usable thread depth. Space is also required for the tap lead & the geometry at the bottom of the drilled hole, so the required finished thread engagement should be considered before drilling begins.

Match the Setup to the Material

Thread size alone doesn't determine the correct operating approach. Workpiece material, tapping depth, tool condition, workholding & operating method can all influence the result.

Where suitable cutting fluid forms part of the setup, Alpha | Lubricants & Cutting Fluids provides related metalworking consumables.

Consider the Finished Assembly

A threaded hole usually exists because another component needs to attach to it. Before drilling, check the fastener diameter, thread pitch, hole position, available material thickness, required engagement, clearance & alignment with the mating component.

If the surrounding hole also requires chamfering, deburring or fastener-head preparation, Sutton Tools | Drills - Countersinks provides related hole-finishing options.

Expert Tips

Don't Guess the Tapping Drill

The preparation-hole diameter influences how much material remains for the tap to cut. Use the tapping drill intended for the required metric thread rather than choosing a drill simply because its diameter appears close.

Pay Attention to the Start

The first engagement establishes the direction of the tap. Starting square to the workpiece helps the thread develop correctly, whereas forcing a tap that has already started on an angle is unlikely to correct the alignment.

Allow Enough Depth in Blind Holes

When a particular amount of usable thread is required in a blind hole, allow for more than the finished thread length. The tap lead & bottom-hole geometry also occupy space, so drilling exactly to the required thread engagement may not provide enough working depth.

Use Each Tap for Its Intended Stage

A bottoming tap's short lead makes it useful for continuing full-form threads closer to the bottom of a suitably prepared blind hole, but that doesn't make it the preferred tool for starting every thread. The taper & intermediate taps provide different lead lengths for different stages of the operation.

Treat Unexpected Resistance as a Warning

If tapping resistance suddenly increases, stop & inspect the setup rather than simply applying more leverage. Alignment, chip behaviour, preparation-hole diameter, tool condition, workpiece material & lubrication where appropriate are all worth checking before continuing.

Maintain the Tools You Use Most

Frequently used sizes can wear differently from taps that rarely leave the case. Clean the taps & drills after use, inspect their cutting edges & return each tool to its intended position. How To Clean Your Gear Without Ruining It provides further practical guidance on looking after workshop equipment.

When cutting performance begins to change, The Black Print: Blade Sharpening 101 Sharpen Or Replace also explores the wider workshop decision of maintaining a cutting edge versus replacing the tool.