Morse Taper (MT) Selection Guide
Explains the dimension table and selection method for the Morse taper shanks (MT2–MT7) used on POINTTECH live centers.
Overview
The Morse taper (MT) is the standard self-holding taper that couples a live center's shank to the sleeve of a lathe tailstock. Its gentle taper of roughly 1.4°–1.5° lets axial thrust seat the shank by friction alone, while a knock-out drives the tool back out for removal. The MT number of your tailstock is the very first thing to verify when selecting a live center: the larger the number, the thicker the shank and the greater the load it can transmit.
Key Features
- Six standard sizes from MT2 through MT7
- Nominal diameter referenced as ΦD at the gauge line
- Self-holding taper angle of approx. 1.4°–1.5° for friction coupling
- Larger numbers mean larger shank diameter, length and permissible load
- Must match the lathe tailstock sleeve size one-to-one
Specifications
Below is the Morse taper dimension table from catalog p3. ΦD is the diameter at the gauge line, Φd is the small-end diameter, a° is the taper half-angle, L is the taper length, and L1 is the knock-out (tang) length. (Unit: mm)
Morse Taper (MT) | ΦD (Gauge line) | Φd | a° | L | L1 |
|---|---|---|---|---|---|
2 | Φ17.780 | 14 | 1°25'50" | 64 | 4 |
3 | Φ23.825 | 19 | 1°26'16" | 79 | 7 |
4 | Φ31.267 | 25 | 1°29'15" | 100 | 9 |
5 | Φ44.399 | 35 | 1°30'26" | 128 | 9 |
6 | Φ63.348 | 51 | 1°29'36" | 179 | 12 |
7 | Φ83.058 | 65 | 1°29'22" | 248 | 12 |
Selection Guide
The MT number cannot be chosen freely; it must match the sleeve size of the lathe tailstock in use. If the tailstock sleeve is MT4, select a live center with an MT4 shank. A reducing sleeve can adapt a smaller shank to a larger bore, but a direct fit is always best for rigidity and accuracy. For heavy workpieces and high cutting loads, choosing a larger MT shank — even with the same head specification — improves thrust transmission and rigidity.
Wipe the taper surface free of coolant, oil and chips before mounting. A contaminated taper causes slippage, increased run-out (TIR) and, in severe cases, shank damage.
Applications
MT2–MT3 are mainly used on small high-speed CNC lathes and precision work, MT4–MT5 on medium conventional lathes and general turning, and MT6–MT7 on large heavy-cutting machines, grinders and big shaft work. Even within the same product family, the workpiece weight and maximum RPM limits vary with MT size, so always check the per-MT specifications in each family's dimension table.