The Bernardo 3-jaw chuck PS3-250 / D5 is a lathe chuck for professional use, with a diameter of 250 mm and a weight of 32 kg. Krollit, official Bernardo distributor since 2007.
- Chuck size: 250/D5
- Diameter: 250 mm
- Taper: 5
- B: 103.5 mm
- D (max.): 82.578 mm
- E: 76 mm
Who uses the PS3-250 / D5 3-jaw chuck and for what purpose
Machine shops and artisan turners use the PS3-250 / D5 3-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 3-jaw chuck PS3-250 / D5 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 in 3-5 business days from Krollit warehouse for spare parts and accessories. Italian-speaking customer support available for technical documentation and compatibility verification with the reference machine. Krollit is an official distributor since 2007.
Who is the PS3-250 / D5 3-jaw chuck for?
The PS3-250 / D5 3-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 metal lathes during turning, drilling, and grooving operations.
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Users with a compatible flanged Bernardo lathe: original replacement or upgrade for Bernardo range 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 4-jaw independent chucks or universal faceplates.
Technical specifications
| Diameter |
250 mm |
| Taper |
5 |
| B |
103.5 mm |
| D (max.) |
82.578 mm |
| E |
76 mm |
| F1 |
104.8 mm |
| Cam-lock bolts |
6 |
| Chuck size |
250/D5 |
| Max. speed |
2000 rpm |
| Approx. weight |
32 kg |
Frequently asked questions
When to use a 3-jaw chuck?
Self-centering 3-jaw chucks are for cylindrical, hexagonal, and 3-6-9-12 sided workpieces. The jaws move together with a single key (self-centering).
It is the most common chuck on lathes: quick clamping of symmetrical workpieces, typical concentricity precision 0.03-0.1 mm depending on the body material (steel = better precision, cast iron = standard).
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-sized workpieces (max. Ø ~220 mm): professional lathes.
The nominal diameter of the chuck indicates the maximum body size, not the maximum workable workpiece size. Clamping capacity depends on the jaw opening (typically 60-70% of the nominal Ø).
What does the D5 mounting indicate?
The D5 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 closing 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.
