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The Perplexing Case of the Morse Taper

Morse Tapers

One of the most common problems of familiarising yourself with a new hobby or area of knowledge is the siege you must lay against the Castle of Terminology. All niche areas of knowledge, by necessity, love to wrapper their facts within impregnable terms. Fine if you know what you are talking about. A struggle until you do.

One of the things that confused me at the outset was the "Morse Taper". Almost every page on a machine tooling catalogue mentions Morse tapers. You have Morse tapers in your headstock, in your tailstock, in the quill of the mill, in the middle of a rotary table.

Avoiding the obvious jokes about reaming, what is a Morse taper? And who the hell is this Morse bloke anyway? This is not the Samuel Morse of dot and dash fame, nor the Endeavour Morse of Jaguar driving and Ale quaffing notoriety. It was a certain Stephen A. Morse in around 1864 who invented the Morse Taper.

Well What is it? Many of the tools we work with are rotary in nature. Either a rotating job is brought into contact with a tool (eg a drill bit in a tailstock) or, like a milling cutting, the tool itself is spun and moved into contact with the job. When attaching the tool to the machine we must be sure of two things. First, it must be properly centred with respect to the axis of rotation, and it must also be quick and simple to swap one such tool for another.

One of the better ways of achieving this is by attaching the tool to a tapered piece of metal (rather like a cone with the top cut off) and fitting it into a hollowed out tapered sleeve. This gives a large surface area of contact between tool and machine. Friction alone will hold a taper in a lathe tailstock.

The Morse Taper is a definition of the profile of such tapers. Morse Tapers come in eight sizes identified by a single digit from 0 to 7. It is almost universally abbreviated with the letters "MT". Thus MT2 is Morse Taper Number 2.

Morse Taper number 0 is the smallest version, perhaps 6cm long, right up to the vast MT7, which is about a foot long. However, it should be noted that the angle of the taper varies with each of the eight. Therefore you cannot fit an MT5 tool into and MT4 sleeve.

Sometimes, especially for collets, the morse taper will have a threaded hole in one end. This allows a drawbar (literally just a length of threaded rod) to be screwed into the end of the Morse Tap from the back of the machine, this draws the Morse Tapered tool into the tapered sleeve and stops it falling out under shock. Alternatively, the Morse Taper will end in a tang that fits into a slot at the end of the tapered sleeve to prevent the tool rotating in the sleeve.

Most of my machine tools have MT2 tapers. My micro-mill and my mini-lathe both had MT2 tapers in their quills and headstocks respectively. The mini-lathe has an MT3 taper in the headstock. IT should be noted that MT2 tooling, eg a chuck, will often end in a long tang. With the tailstock of a mini-lathe you can utilise neither a tang nor a drawbar, therefore it is best to shorten the Morse Taper on such tools to remove the tang. This is best done with a heavy duty cutting disk in a dremel. I suppose an angle grinder would work just as well.

I've often found that machine tools tend to come with some weird threaded for an imperial drawbar. However, my mill has a M10 drawbar. To avoid swapping drawbars, I've often tapped out my MT2 tools to M10 with no problem.

a range of morse taper tools

A Morse Taper Reamer is a special type of reamer for making hole fit the Morse Taper internally. Making a Morse taper to fit into such a sleeve can be done on the lathe with much mucking about with angles and so forth.

Above is an image show a variety of MT2 tooling. Two collects, a 13mm chuck and a flycutter.

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