Tapers

Jacobs Taper

The Jacobs Taper (abbreviated JT eg JT0 or JT3) is commonly used to secure drill press chucks to an arbor.

Taper Large End Small End Length Taper/
Foot
Taper/
Inch
1/2 Included Angle
#0 0.2500″ 0.2284″ 0.44″ .5915 .0493 1.4117°
#1 0.3840″ 0.3334″ 0.66″ .9251 .0771 2.2074°
#2 0.5590″ 0.4876″ 0.88″ .9786 .0816 2.3350°
#2 Short 0.5488″ 0.4876″ 0.75″ .9786 .0816 2.3350°
#3 0.8110″ 0.7461″ 1.22″ .6390 .0532 1.5251°

 

Morse Taper

A self-holding standard taper largely used on small cutting tools such as drills, mills, and reamers, and, on some machines, spindles in which these tools are used.

When used in milling machines it is normal for the taper to be pulled into place with a threaded bar.

Morse Taper No. Gauge Depth (inches) Gauge Diameter (inches) Hang (inches) Taper per inch 1/2 included angle °
0 2 0.252 1/8 0.05205 1° 29′ 30”
1 21/8 0.369 1/8 0.04988 1° 26′
2 29/16 0.572 3/16 0.04995 1° 26′
3 33/16 0.778 3/16 0.05020 1° 26′ 15”
4 41/16 1.02 1/4 0.05194 1° 29′
5 53/16 1.475 1/4 0.05263 1° 30′ 30”
6 71/4 2.116 5/16 0.05214 1° 30′
7 10 2.75 3/8 0.052 1° 30′

 

Care Points:

  • make sure the taper is free from dust and dirt
    • small particles can damage the taper if it rotates under load
  • do not oil the taper for assembly
    • this is likely to result in a locked and difficult to remove taper
    • if left over a long time this can result in a corroded taper joint
About Nigel 169 Articles
Have been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

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