BT50 ER collet chucks
BT50 ER25 Collet Chucks (MAS 403): Gauge Lengths 80, 100, 150, 200, 250, 260 and 300 mm
BT50 ER25 collet chucks hold round-shank drills, reamers and end mills in a DIN 6499 ER25 collet, closed by the ER25 clamping nut (M18x1.5). PTP makes them with a BT shank (MAS 403 / JIS B6339, ISO 7388-2 type J) in gauge lengths of 80, 100, 150, 200, 250, 260 and 300 mm, for tool shanks of 1–16 mm. Ordering codes: 7. BT50 holders are pulled into the spindle by an M24 MAS-BT or JIS B6339 pull stud. Taper AT3 or better, TIR 0.005 mm max, balanced G2.5 @ 25,000 rpm.
BT50 ER25 collet chucks: 7 ordering codes
Every ordering code opens its own page with the drawing and every dimension (mm).
| Ordering code | Clamping Range | Nut Ø (d) | Gauge Length (GPL) | GPL Long |
|---|---|---|---|---|
| 47BT50ER2580 | 1–16 mm | 42 mm | 80 mm | 160 mm |
| 47BT50ER25100 | 1–16 mm | 42 mm | 100 mm | – |
| 47BT50ER25150 | 1–16 mm | 42 mm | 150 mm | – |
| 47BT50ER25200 | 1–16 mm | 42 mm | 200 mm | – |
| 47BT50ER25250 | 1–16 mm | 42 mm | 250 mm | – |
| 47BT50ER25260 | 1–16 mm | 42 mm | 260 mm | – |
| 47BT50ER25300 | 1–16 mm | 42 mm | 300 mm | – |
BT50 ER25 collet chuck
PTP catalogue drawing, dimensions in mm

Questions about BT50 ER25 collet chucks
What is the clamping range of a BT50 ER25 collet chuck?
1–16 mm. ER25 collets to DIN 6499 clamp tool shanks from 1 to 16 mm, one collet for each size step.
Which pull stud does a BT50 ER25 collet chuck need?
An M24 BT50 pull stud: MAS-BT with the head angle your drawbar takes (45°, 60° or 90°), or JIS B6339 with a 15° head.
Which nut and collets fit a BT50 ER25 collet chuck?
ER25 collets to DIN 6499 and the ER25 clamping nut: slotted 36CCNER25. For coolant-through tools, an ER25 sealing ring (11 sizes, 36CCNER25SR060 to 36CCNER25SR160).
