The Bernardo 3-jaw steel chuck PO3-315/D6 is a lathe chuck for professional use, with a diameter of 315 mm and a weight of 51 kg. Krollit, official Bernardo distributor since 2007.
- Chuck size: 315/D6
- Diameter: 315 mm
- Taper: 6
- B: 96.2 mm
- d: 106.390 mm
- E: 103 mm
Who uses the PO3-315/D6 3-jaw steel chuck and for what
Mechanical workshops and artisan turners use the PO3-315/D6 3-jaw steel chuck as a clamping accessory on metal lathes, ensuring secure clamping and centering of the workpiece in turning, drilling, and grooving operations.
Its place in the Bernardo range
The Bernardo PO3-315/D6 3-jaw steel chuck 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 assistance with selection.
Krollit logistics and support
Shipping within 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 PO3-315/D6 3-jaw steel chuck for
The PO3-315/D6 3-jaw steel 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 in turning, drilling, and grooving operations.
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Users with compatible flange Bernardo lathes: original replacement or upgrade for Bernardo range lathes (profi, hobby, etc.) with A2 attachment conforming to DIN 55029.
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Irregular or non-round shaped workpieces: for non-symmetrically centered workpieces, consider 4-jaw independent chucks or universal platforms.
Technical specifications
| Diameter |
315 mm |
| Taper |
6 |
| B |
96.2 mm |
| d |
106.390 mm |
| E |
103 mm |
| F1 |
133.4 mm |
| Cam-lock bolts |
6 |
| Chuck size |
315/D6 |
| Max. speed |
2800 rpm |
| Approx. weight |
51 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).
Why a steel chuck instead of cast iron?
Steel chucks (PO series) offer superior concentricity precision (0.01-0.03 mm) and greater wear resistance in intensive machining.
Ground steel: higher weight, but smaller dimensions for the same nominal Ø. Suitable for series production and precision turning on treated steels or hard alloys.
What workpieces is the Ø 315 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 that of the workable workpiece. The clamping capacity depends on the jaw opening (typically 60-70% of the nominal Ø).
What does the D6 taper 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.
Check the taper of your lathe before purchasing: the interface flange must exactly match the code. Camlock = quick clamping 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 ground bar and measuring with a dial indicator: acceptable tolerance 0.03-0.1 mm depending on the model.
