Four-Jaw Chucks

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Four-Jaw-Chucks

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Four-Jaw Chucks

For-Jaw Chuck Holding Workpiece.jpg
Synonyms: four-jaw scroll chucks; DE: Vierbackenfutter
Type: workholding (woodturning)
Material: wood
Used with: Tyme Avon or Holzmann D 460F wood lathes;
(optional) dovetail scraper
Location: woodturning area
Access Requirements: read this page & manuals where available
Tutors: Lukas
Manual: see list
Similar (More or Less): three-jaw chucks, precision combination chuck,
faceplates

Four-jaw chucks are a very nice workholding option for woodturning projects that can't be held between centers (e.g. bowls).

They do not automatically center a workpiece like three-jaw chucks you may know from metal turning, but have other advantages to work especially well with wood.

The chucks come with different jaw sets (Spannbacken) for different diameters. Take care to put them in the correct order - most jaws will be numbered and only close in a neat point or square if you match them with the proper spot on the chuck.

You usually don't use the "pointy" base jaws to directly hold a woodturning blank because they dent the wood! Instead, in the first step a recess or tenon (Zapfen) with the exact jaw diameter (and often a dovetail profile) is turned with other workholding options and the workpiece is then flipped around to be held by the chuck.

Precision

The holding force is best when the jaw diameter (and shape) matches the workpiece precisely as specified in the manual (e.g. SuperNova²: 6 mm larger/smaller than the jaw diameter when fully closed/opened). Reportedly, it can be improved further by tightening both chuck screws, not just one. HolzWerken 99

We could make laser cut templates for the various jaw sets' ideal diameters!

Turning green wood can be an exception to this rule: keeping in mind shrinkage, you may want to oversize your tenon during the first round of rough turning so you can cut it to the proper size when you finish the piece. [1]

Available Chuck/Jaw Combinations

The chucks are screwed onto a wood lathe's spindle screw, so they are somewhat machine specific based on the thread.

Photo Chuck Jaw Set Manual Workpiece (OD) Workpiece (ID) Thread Lathe(s) Adjustment Tools Further Parts/Notes
SuperNova2 + Woodworm screw.jpg SuperNova² 50 mm dovetail (standard) teknatool.com 45-65 mm (ideal: 50 mm) 50-75 mm (ideal: 67 mm) M25 × 2 mm with adapter (native: M33 × 3.5 mm) Tyme Avon 4 & 8 mm hex keys "Woodworm" screw for fast mounting of rough material
SuperNova2 Cole jaws.jpg SuperNova² Cole jaws teknatool.com - page 40 56-236 mm nope M25 × 2 mm with adapter (native: M33 × 3.5 mm) Tyme Avon 9 mm slot screwdriver 8 rubber buffers - required!
Four-jaw chuck dovetail.jpg noName (CoMS 051) 80(?) mm dovetail 47-77 mm (?) 63-95 mm (?) M33 × 3.5 mm Holzmann D 460F 4 & 10 mm hex keys 24 step indexing plate (attached)
Four-jaw chuck stepped.jpg noName 80(?) mm stepped/"pointy" 5-53 mm (?) 63-95 mm (?) M33 × 3.5 mm Holzmann D 460F 8 mm round steel handles jaw numbers pointing outward have to match the base numbers

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