Four-Jaw Chucks
(Redirected from Scroll Chucks)
Four-Jaw-Chucks
| AccessoryInfoBox Four-Jaw Chucks | |
|---|---|
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| 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.
four-jaw chuck (SuperNova²) with two very different jaw sets
four-jaw chuck without any jaws on the jaw slides (for small pieces that fit through the center bore)
four-jaw chuck holding a workpiece
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 | 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 | 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! |
|
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) | |
|
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 |
Helpful Videos
- wortheffort: Woodturning Chucks, Jaws, Tenons and Recesses - detailed explanations (36 min) of hardware and strategies to maintain the strength of the wood
- Mike Waldt: Woodturning - How to Hold Work Securely in a Chuck - short demonstration (10 min) of proper tenon/recess diameters
- Woodworker's Journal: Scroll Chuck Basics - rough overview (4 min) of the chuck's operation
- Maschinenhandel Meyer: Gefährlich und ungenau - welches Drechselfutter eignet sich zum Drechseln...und welches nicht! - (DE) Kaufberatung mit vielen wichtigen allgemein gültigen Punkten
