What are the Dimensions and Angles of Morse Tapers and Jacobs Tapers?

A machine taper, frequently referred to as a “drill sleeve,” is a means for securing toolholders or cutting tools in the spindle of a power tool or machine tool. A conical-shaped male member with a taper fits into the female socket, which has a matching taper at an equal angle. They hold based on the friction action of the mating surfaces and the wedging action of the taper. Many power tool spindles, along with most machine tool spindles, use tapers as a way to attach tools. This guide will look at two of the most common types of tapers—Jacobs and Morse—some tools they work on, and different sizes and angles available.

Often, machine tool operators need to remove or install tool bits easily and quickly. Whether it's a drill press, handheld drill, or lathe, which have chucks (such as a drill chuck or collet chuck), the chuck is attached by a taper. A machine tool taper is a simple, versatile, highly repeatable, and low cost tool-mounting system. The taper provides indexability, as tools can be quickly changed, while also being precisely located both axially and concentrically by the taper.

Morse and Jacobs tapers are examples of self-holding tapers. This means the male and female wedge together and bind to each other to the extent that the forces of drilling can be resisted without a drawbar. A drawbar, or spindle drawbar, is a clamping mechanism for tool holders on machine tools. The toolholder or machine taper itself is held by the drawbar and applies force to the spindle, especially when spinning at low speeds. When at idle, the tool will still stay in the spindle due to the drawbar. If a tool change is needed, it is driven out with a wedge.

Machinists are taught to take great care when handling Morse and Jacobs tapers as they are sensitive to nicks, dents, chips and dirt. When aligning the male conical taper with the female socket, if there are any imperfections or dirt, the pieces won't locate accurately nor hold reliably, leading to potential wobble and chatter of the workpiece. Taper shanks can easily be wiped clean. However, sockets, being deep and inaccessible, are best cleaned with a specialized taper cleaning tool which is inserted, twisted, and then removed. 

The Jacobs taper, regularly abbreviated as JT, is most often used to secure drill press chucks to an arbor. The taper angles aren't consistent, varying from 1.41° per side for #0 (and the obscure #​2-1/2) to 2.33° per side for #2 (and #2 short). There are also several sizes between #2 and #3: #2 short, #6 and #33.

The Morse taper was named for and developed by Stephen A. Morse in the mid-1860s. Today, it's still one of the most widely used tapers, and is common on the shank of taper-shank twist drills and machine reamers, in the spindles of industrial drill presses, and in the tailstocks of lathes. The taper angle of the Morse taper varies somewhat with size but is typically 1.49°. They come in eight sizes identified by whole numbers between 0 and 7, and one rarely found or used half-size, 4-1/2. Often the designation is abbreviated as MT followed by a digit (for example, a Morse taper number 4 would be MT4).

Check on Zoro.com for all your Morse tapers, Morse taper extensions, and Morse taper extension sockets.

The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.