The Bernardo 4-jaw chuck DK12-400/D8 is a professional-grade lathe chuck with a diameter of 400 mm and a weight of 101 kg. Krollit has been the official Bernardo distributor since 2007.
- Chuck size: 400/D8
- D - Diameter: 400 mm
- Taper: 8
- D1 (max.): 139.734 mm
- D2: 171.4 mm
- D3: 130 mm
Who uses the DK12-400/D8 4-jaw chuck and for what
Mechanical workshops and artisan turners use the DK12-400/D8 4-jaw chuck as a clamping accessory on metal lathes, ensuring secure clamping and workpiece centering during turning, drilling, and grooving operations.
Its place in the Bernardo range
The Bernardo 4-jaw chuck DK12-400/D8 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 service for selection support.
Krollit logistics and support
Shipping within 3-5 business days from Krollit warehouse for spare parts and accessories. Customer service in Italian available for technical documentation and compatibility verification with the reference machine. Krollit has been an official distributor since 2007.
Who is the DK12-400/D8 4-jaw chuck for
The DK12-400/D8 4-jaw chuck is recommended for the following professional profiles:
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Mechanical workshops and artisan turners: Secure clamping of round or hexagonal workpieces on metal lathes for 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 according to DIN 55029.
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Irregular or non-round shaped workpieces: For non-symmetrically centered workpieces, consider independent 4-jaw chucks or universal platforms.
Technical specifications
| Chuck size |
400/D8 |
| D - Diameter |
400 mm |
| Taper |
8 |
| D1 (max.) |
139.734 mm |
| D2 |
171.4 mm |
| D3 |
130 mm |
| H1 |
126 mm |
| Max. speed |
1000 rpm |
| Approx. weight |
101 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 off-center (eccentric, asymmetrical) 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 intensity of use and required tolerance: steel for production and precision, cast iron for general use.
What workpieces is the Ø 400 mm diameter suitable for?
Suitable for medium-large workpieces (max. Ø ~360 mm): industrial lathes.
The nominal diameter of the chuck indicates the maximum body size, not the maximum machinable workpiece size. Clamping capacity depends on jaw opening (typically 60-70% of nominal Ø).
What does the D8 mounting 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 mounting of your lathe before purchase: the interface flange must exactly match the code. Camlock = quick-release with cams, disassembly in 30 seconds without tools.
How to maintain chuck precision?
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.
