Jacobs Taper Dimensions
The Jacobs Taper (JT) is commonly used to secure a drill chuck to an arbor.
The dimension below should help you identify the correct arbor for your chuck
(or vice-versa!)
.
| Jacobs Taper |
Small End | Big End | Length | |||
|---|---|---|---|---|---|---|
| mm | inch | mm | inch | mm | inch | |
| JT0 | 5.80 | 0.2284 | 6.35 | 0.2500 | 11.11 | 0.4375 |
| JT1 | 8.47 | 0.3334 | 9.75 | 0.3840 | 16.67 | 0.6563 |
| JT2 | 12.39 | 0.4876 | 14.20 | 0.5590 | 22.23 | 0.8750 |
| JT2 Short | 12.39 | 0.4876 | 13.94 | 0.5488 | 19.05 | 0.7500 |
| JT33 | 14.23 | 0.5604 | 15.85 | 0.6240 | 25.40 | 1.000 |
| JT6 | 15.85 | 0.6241 | 17.17 | 0.6760 | 25.40 | 1.000 |
| JT3 | 18.95 | 0.7461 | 20.60 | 0.8110 | 30.96 | 1.2188 |
| JT4 | 26.34 | 1.0372 | 28.55 | 1.1240 | 42.07 | 1.6563 |
| JT5 | 33.43 | 1.3161 | 35.89 | 1.4130 | 47.63 | 1.875 |
If your chuck dimensions don't match a taper in the above table then it's possible
you have a DIN 238 taper e.g. B12 or B16.
| DIN 238 Taper |
Small End mm |
Big End mm |
Length mm |
|---|---|---|---|
| B10 | 9.4 | 10.095 | 14.5 |
| B12 | 11.1 | 12.065 | 18.5 |
| B16 | 14.5 | 15.733 | 24 |
| B18 | 16.2 | 17.78 | 32 |
| B22 | 19.8 | 21.793 | 40.5 |