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Built for metal lathes, wood lathes, drill presses, milling machines, CNC machining centers, grinders, and other equipment that needs self-centering workholding. The TOP-TOOL 320 mm chuck delivers rigid gripping when mounted with the correct adapter plate or fixture. HT300 cast iron body, AISI 5140 scroll and bevel gears, AISI 1045 jaws. Overall clamping envelope 11.5–320 mm (0.45–12.60 in) across the three modes below.
| Component | Material | Hardness (HRC) |
|---|---|---|
| Body | HT300 Cast Iron | — |
| Jaws | AISI 1045 Carbon Steel | 52–58 |
| Scroll Plate | AISI 5140 Alloy Steel | 43–48 |
| Bevel Gears | AISI 5140 Alloy Steel | 45–50 |
| Back Plate | Aluminum / Engineered Plastic | — |
Outside clamping with solid outside jaws (standard setup): 11.5–145 mm gripping on the outside diameter.
Inside support / expanding with the same outside jaws: 95–320 mm internal gripping (boring-style holding).
Outside clamping with solid inside (reverse) jaws: 110–320 mm for large-diameter OD work.
Summary: overall envelope 11.5–320 mm (0.45–12.60 in) depending on jaw configuration.
This listing uses one-piece solid jaws. For chucks with two-piece master and top jaws, see our other listings.
Dimensions per factory charts Dimensions.webp / Dimensions-2.webp; clamping per clamping-range chart.
| Parameter | Value |
|---|---|
| Chuck Diameter (D) | 320 mm (12.60 in) |
| D1 (register / locating recess diameter) | 265 mm |
| h (depth of D1 register recess) | 7.5 mm |
| D2 (bolt circle diameter) | 290 mm |
| D3 (through hole diameter) | 100 mm |
| H (total thickness: body + jaws) | 155 mm |
| H1 (body thickness only, excluding jaw height) | 90 mm |
| H2 | 96 mm |
| Clamping (outside jaws, standard OD) | 11.5 – 145 mm |
| Clamping (inside expand, same outside jaws) | 95 – 320 mm |
| Clamping (outside with reverse jaws) | 110 – 320 mm |
| Overall span (reference) | 11.5 – 320 mm (0.45 – 12.60 in) |
| Mounting | 3× M16 |
| Repeatability | ≤0.05 mm (0.002") |
| Net Weight | 40.1 kg |
Jaws and body are numbered (1, 2, 3) so each jaw matches its slide—faster setup and better concentricity.
Machine swing or envelope must clear the chuck body and fully opened jaws. Plan a comfortable margin above nominal diameter D. Your adapter must match D1, D2, and the bolt pattern listed above.
Clean regularly. Apply molybdenum disulfide (MoS2) grease to the scroll and bevel gears.
Never run with the chuck key engaged. Observe safe speeds for chuck size and workpiece balance.
HT300 AISI1045 AISI 5140
Included Accessories
T-Key,Bolts ,External Jaws(One-piece Jaw Chuck)
Backplate not included.
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