The Bernardo 4-jaw chuck PS4-250 is a professional-grade lathe chuck, weighing 29 kg. Krollit, official Bernardo distributor since 2007.
- Chuck size A: 250
- B: 85 mm
- C: 5 mm
- d: 200 mm
- E: 76 mm
- F: 224 mm
Who uses the 4-jaw chuck PS4-250 and what for
Mechanical workshops and artisan turners use the 4-jaw chuck PS4-250 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 PS4-250 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 performance: 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 within 3-5 working 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 4-jaw chuck PS4-250 for?
The 4-jaw chuck PS4-250 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 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 platforms.
Technical specifications
| B |
85 mm |
| C |
5 mm |
| d |
200 mm |
| E |
76 mm |
| F |
224 mm |
| G |
M12 |
| h |
105 mm |
| J |
34 mm |
| Chuck size A |
250 |
| Max. speed |
2000 rpm |
| Approx. weight |
29 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.
Which workpieces are suitable for a Ø 250 mm diameter?
Suitable for medium workpieces (max Ø ~220 mm): professional lathes.
The nominal chuck diameter indicates the maximum body size, not the machinable workpiece size. Clamping capacity depends on jaw opening (typically 60-70% of nominal Ø).
How do I check compatibility with my lathe?
Check the type of lathe spindle nose (Camlock D3-D15, or threaded M-mount) and the corresponding diameter.
On modern lathes, Camlock mounting is the most common. On older lathes, there may be a threaded (M-) or flanged mount. The lathe's technical documentation indicates the exact type.
How is the chuck's 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.
