Sherline 4-Jaw Chuck for Pocket NC

Independent 4-jaw chuck workholding for the Pocket NC. Sherline-made, Pocket NC trunnion adapter included. Hold round, square, or irregular stock — including off-centre and asymmetric workpieces — with the precision and clamping force a 3-jaw or vise can't match.

Why a 4-jaw chuck

A 3-jaw self-centering chuck only grips concentric round stock. A vise only grips parallel-sided stock. The 4-jaw independent chuck holds anything you can pull into the centre with four screws — round, square, hex, rectangular, cast forms, and intentionally off-axis features.

For Pocket NC owners, this opens up:

• Watch components & jewellery — eccentric features, off-centre bores, small cylindrical stock
• Cast parts — clamp on the rough exterior while machining the inside
• Long round stock — turn-style holding for cylindrical workpieces longer than vise jaws can grip
• Off-axis features — clamp a part deliberately off-centre to machine bolt holes or sockets at an offset
• Hexagonal & square stock — direct gripping without soft-jaw machining

Specifications

What's in the box

• Sherline 4-jaw independent chuck
• Set of 4 reversible jaws (already installed)
• Pocket NC trunnion adapter plate
• Chuck key
• 4× M5 mounting screws
• Setup guide

Setup on the Pocket NC

1. Remove your existing vise or fixture from the trunnion table
2. Bolt the Pocket NC adapter plate to the trunnion using the 4× M5 cap screws
3. Mount the chuck onto the adapter — register pin aligns the chuck centre to the trunnion centre
4. Tighten the chuck retainer
5. Re-set your G54 origin (trunnion centre is now the chuck face)
6. For dial-indicated truing: rotate the trunnion to expose each jaw, adjust each jaw screw until the indicator reads within target tolerance

4-jaw vs LANG vise vs standard Pocket NC vise

FAQ

Will it fit the V2-50 too?

Yes — same trunnion mounting pattern across V2-10 and V2-50 (CHB and CHK). The adapter plate is universal.

Can I use soft jaws?

Yes. The four installed jaws are reversible hard jaws; Sherline soft jaws (aluminium, brass) are sold separately for delicate finished surfaces.

Will it interfere with B-axis rotation?

Within the standard Pocket NC trunnion clearance envelope (the chuck height + workpiece must fit under the spindle at full B/A rotation). For tall workpieces, validate clearance in the simulator at sim.pentamachine.com before cutting.

Lead time?

In stock at Köln — same-day shipment for orders before 14:00 CET. Sherline manufacturing in California; restock from factory is 2–3 weeks if we're out.

Returns?

14-day return for private buyers under EU Widerrufsrecht. Commercial returns subject to our AGB. See Returns & Refunds.

Pair with

• Annual Maintenance Contract — keep the machine calibrated for the precision the chuck unlocks
• Owner training course — module on workholding strategy
• Forum thread: Fixture and workholding ideas — community-curated setups