The Bernardo DK12-250/D8 4-jaw chuck is a professional lathe chuck, with a diameter of 250 mm and a weight of 32 kg. Krollit has been an official Bernardo distributor since 2007.
- Chuck size: 250/D8
- D - Diameter: 250 mm
- Taper: 8
- D1 (max.): 139.734 mm
- D2: 171.4 mm
- D3: 80 mm
Who uses the DK12-250/D8 4-jaw chuck and what for?
Machine shops and artisan turners use the DK12-250/D8 4-jaw chuck as a clamping accessory on metal lathes, ensuring secure clamping and centering of the workpiece during turning, drilling, and grooving operations.
Its place in the Bernardo range
The Bernardo DK12-250/D8 4-jaw chuck is part of Bernardo's range of lathe chucks, distributed in Italy by Krollit since 2007. The Bernardo range includes models of various categories and performances: to choose the right machine for your use case, you can consult the Bernardo catalog on Krollit or contact customer support for assistance with selection.
Krollit logistics and support
Shipping within 3-5 business days from Krollit warehouse for spare parts and accessories. Italian customer support available for technical documentation and compatibility verification with the reference machine. Krollit has been an official distributor since 2007.
Who is the DK12-250/D8 4-jaw chuck for?
The dk12-250/d8 4-jaw chuck is recommended for the following professional profiles:
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Machine shops and artisan turners: secure clamping of round or hexagonal workpieces on a metal lathe during turning, drilling, and grooving operations.
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Users with a Bernardo lathe with a compatible flange: original replacement or upgrade for Bernardo range lathes (profi, hobby, etc.) with A2 mount conforming to DIN 55029.
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Irregular or non-round workpieces: for asymmetrically uncentered workpieces, consider independent 4-jaw chucks or universal faceplates.
Technical specifications
| Chuck size |
250/D8 |
| D - Diameter |
250 mm |
| Taper |
8 |
| D1 (max.) |
139.734 mm |
| D2 |
171.4 mm |
| D3 |
80 mm |
| H1 |
96.5 mm |
| Max. speed |
1600 rpm |
| Approx. weight |
32 kg |
Frequently Asked Questions
When to use a 4-jaw chuck?
Self-centering 4-jaw chucks are for square and 4-8 sided workpieces. The jaws move together with a single key.
The self-centering 4-jaw chuck (not independent jaws) clamps square or octagonal workpieces symmetrically. For eccentric (asymmetric) clamping, independent jaw chucks are needed.
What material is the chuck body made of?
The material is indicated in the title: steel (PO series) for maximum precision, cast iron (DK/PS series) for standard use.
The choice depends on the intensity of use and required tolerance: steel for production and precision, cast iron for general use.
What workpieces is the Ø 250 mm diameter suitable for?
Suitable for medium workpieces (max Ø ~220 mm): professional lathes.
The nominal diameter of the chuck indicates the maximum size of the body, not that of the workable workpiece. The clamping capacity depends on the jaw opening (typically 60-70% of the nominal Ø).
What does the D8 taper indicate?
The D8 code (Camlock according to DIN 55029) identifies the size of the lathe spindle nose: D3-D5 for small lathes, D6-D8 for medium, D11-D15 for industrial.
Check the taper of your lathe before purchasing: the interface flange must exactly match the code. Camlock = quick-release with cams, disassembly in 30 seconds without tools.
How is chuck precision maintained?
Regular cleaning of the spiral mechanism, periodic lubrication with specific chuck grease, concentricity check every 6 months with a dial indicator.
A jaw that moves with difficulty indicates chips or rust in the mechanism: disassemble, clean, and grease. Concentricity is checked by mounting a rectified bar and measuring with a dial indicator: acceptable tolerance 0.03-0.1 mm depending on the model.
