The Bernardo 4-jaw steel chuck PO4-500 is a professional-grade lathe chuck, weighing 145 kg. Krollit, official Bernardo distributor since 2007.
- Chuck size A: 500
- B: 119 mm
- C: 5 mm
- d: 420 mm
- E: 190 mm
- F: 458 mm
Who uses the PO4-500 4-jaw steel chuck and for what purpose
Mechanical workshops and artisan turners use the PO4-500 4-jaw steel chuck as a clamping accessory on metal lathes, ensuring secure locking and centering of the workpiece during turning, drilling, and grooving operations.
Its place in the Bernardo range
The Bernardo PO4-500 4-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 selection assistance.
Krollit logistics and support
Shipping 3-5 business 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 PO4-500 4-jaw steel chuck for?
The po4-500 4-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 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 spindle nose compliant with DIN 55029.
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Irregular or non-round workpieces: for asymmetrically centered workpieces, consider 4-jaw independent chucks or universal platforms.
Technical specifications
| B |
119 mm |
| C |
5 mm |
| d |
420 mm |
| E |
190 mm |
| F |
458 mm |
| G |
M16 |
| h |
180 mm |
| J |
60 mm |
| Chuck size A |
500 |
| Max. speed |
1200 rpm |
| Approx. weight |
145 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.
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 operations.
Ground steel: higher weight, but smaller dimensions for the same nominal diameter. Suitable for series production and precision turning of treated steels or hard alloys.
What workpieces is the Ø 500 mm diameter suitable for?
Suitable for large workpieces (max Ø ~600 mm): heavy 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).
How do I check compatibility with my lathe?
Check the type of lathe spindle nose mounting (Camlock D3-D15, or threaded M-attachment) and the corresponding diameter.
On modern lathes, Camlock mounting is the most common. Older lathes may have a threaded (M-) or flanged attachment. 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.
