Morse Taper was invented by Stephen A. Morse (also the inventor of the
twist drill) circa 1864. Since then it has evolved to encompass smaller
and larger sizes and has been adopted as a standard by numerous
organizations including ISO as ISO 296:1991 Machine Tools --
Self-Holding Tapers for Tools Shanks, and DIN as DIN 228-1:1987-05 Morse
tapers and metric tapers; taper shanks.
Morse Tapers come in eight sizes identified by number
between 0 and 7. Often this is abbreviated as MT followed by a digit,
for example a Morse taper number 4 would be MT4. The MT2 taper is the
size most often found in drill presses up to 1/2" capacity.
Morse tapers can have two types of ends:
taper itself is roughly 5/8" per foot, but exact ratios and dimensions
for the various sizes of tang type tapers are given below.
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and Sharpe tapers are an alternate to the more-commonly seen Morse
taper. Like the Morse, these have a series of sizes, from 1 to 18, with
7, 9 and 11 being the most common. Actual taper on these is within a
close range of .500 per foot.
The Jacobs Taper (abbreviated JT) is commonly used to secure drill press chucks to an arbor.
tapers range from a Number 2 to a Number 20. The diameter of the big
end in inches is always the taper size divided by 8, the small end is
always the taper size divided by 10 and the length is the taper size
divided by 2. For example a Jarno #7 measures 0.875" (7/8) across the
big end. The small end measures 0.700" (7/10) and the length is 3.5"