The Bernardo 4-jaw chuck DK12-400/D6 is a professional-grade lathe chuck with a diameter of 400 mm and a weight of 101 kg. Krollit, official Bernardo distributor since 2007.
- Chuck size: 400/D6
- D - Diameter: 400 mm
- Taper: 6
- D1 (max.): 106.390 mm
- D2: 133.4 mm
- D3: 103 mm
Who uses the DK12-400/D6 4-jaw chuck and for what
Mechanical workshops and artisan turners use the DK12-400/D6 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 4-jaw chuck DK12-400/D6 is part of the Bernardo lathe chuck range, 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 selection assistance.
Krollit logistics and support
Shipping 3-5 working days from Krollit warehouse for spare parts and accessories. Customer support 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/D6 4-jaw chuck for
The dk12-400/d6 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 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 lathes (profi, hobby, etc.) with A2 mounting conforming to DIN 55029.
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Irregular or non-round workpieces: for non-symmetrically centered workpieces, consider independent 4-jaw chucks or universal faceplates.
Technical specifications
| Chuck size |
400/D6 |
| D - Diameter |
400 mm |
| Taper |
6 |
| D1 (max.) |
106.390 mm |
| D2 |
133.4 mm |
| D3 |
103 mm |
| H1 |
126 mm |
| Max. speed |
1000 rpm |
| Weight approx. |
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, 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 the 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 size of the body, not the machinable workpiece. The clamping capacity depends on the jaw opening (typically 60-70% of the nominal Ø).
What does the D6 mounting indicate?
The D6 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 ones.
Check your lathe's mounting before purchasing: the interface flange must exactly match the code. Camlock = quick clamping 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 ground bar and measuring with a dial indicator: acceptable tolerance 0.03-0.1 mm depending on the model.
