The Vicmarc 4 Jaw Self-Centering Chuck is a precision-engineered woodturning accessory manufactured by Vicmarc Machinery Pty Ltd in Australia. Designed for both hobbyists and professional woodturners, this chuck is available in several models: VM90, VM100, VM120, VM140, and VM150. It is designed to grip workpieces both internally and externally, accommodating round and square stock. A key feature is its hollow center, which allows for through boring from either end, and it can be run in both clockwise and anticlockwise directions.
Technical Specifications and Construction:
The chucks are manufactured from K1045 (medium tensile steel - 45 tonne), ensuring high durability, a longer lifespan, and a high-quality finish that is less susceptible to rust. Vicmarc chucks come with a 12-month guarantee.
Function Description:
The primary function of the Vicmarc 4 Jaw Self-Centering Chuck is to securely hold workpieces on a woodturning lathe. Its self-centering mechanism ensures that the workpiece is accurately centered for turning operations. The chuck's design allows for quick and efficient mounting and dismounting of bowls and other turning projects.
Mounting on the Lathe:
The Vicmarc Uni-Chuck is adaptable to a wide range of lathe spindle sizes through the use of interchangeable threaded inserts. Users are advised to consult their dealer for the correct insert for their specific lathe. It is crucial to ensure that the insert is firmly screwed into the chuck body and that the assembled chuck is then firmly seated against the lathe spindle shoulder.
Screw Point Usage:
Each Vicmarc Chuck is supplied with a "Screw Point" for mounting small cross-grained pieces. The screw point should be mounted as described in the manual (page 6). Incorrect mounting can cause damage. Recommended drilled hole sizes for the screw point are 7mm - 7.5mm for softwoods and 8mm - 8.5mm for hardwoods. Where possible, drilling should be done on a pillar drill for accuracy.
Clamp Mode:
In clamp mode, the workpiece is held externally by the jaws. For a secure hold, the bowl end should be pressed firmly against the jaws. Workpieces can also be fastened to the screw point or a face plate. When pre-turning bowls from green timber, it is possible to turn a 5mm to 10mm deep dovetail recess between centers or with a pivot chuck.
Expansion Mode:
For expansion mode, a recess is turned into the workpiece. The depth of this recess depends on the workpiece size and timber type, with a minimum recommended depth of 5mm to 10mm.
Specific Model Features:
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VM90 and VM140: These models are operated using quick-acting Tommy Bars (Levers), which save time during mounting and dismounting. The VM90 is compact, suitable for 300mm (12") capacity lathes or smaller, while the VM140 can handle work up to 500mm (20") in diameter with standard jaws. The basic chuck package includes the chuck body, two tommy bars, a screw point, an allen key, and the owner's manual.
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VM100 and VM120: These models are T-bar allen key operated, offering one-hand tightening and tremendous gripping power due to a 6 to 1 scroll ratio. The totally enclosed back ensures smooth action by preventing dust and debris from entering the scroll. Keyed chucks are known for their holding power. The VM100 is ideal for 300mm (12") capacity lathes or smaller, and the VM120 can manage work up to 500mm (20") in diameter with standard jaws. The basic chuck includes the chuck body, a T-bar allen key, a screw point allen key, and the owner's manual.
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VM150: This is an innovative, patented design with exceptional features for professional and serious hobbyist turners. Jaws and inserts are compatible with the VM120, but the backing jaws are larger and stronger for heavy use. The VM150 is suitable for 400mm (16") capacity lathes or larger. It offers two actions: a quick-action lever operation for rapid opening and closing (fully open in 3 revolutions) and a T-key operated fine adjustment for tightening, similar to a standard scroll chuck. To switch between modes, users align dots and rotate the locking pinion with the 10mm T-bar (clockwise to engage, anti-clockwise to disengage). The basic chuck includes the chuck body, one tommy bar, a screw point, two allen keys, and the owner's manual.
Maintenance Features:
To ensure optimum performance and a long working life, regular maintenance is crucial.
- Cleaning: Before mounting, ensure all threads are thoroughly clean and free of debris for true running. Regularly inspect the chuck for dust buildup in the scroll and jaws and clean as required.
- Lubrication: The chuck is engineered to close tolerances and may initially be stiff. To maintain easy jaw action, regularly spray oil onto the scroll and work lever through its full range of movement.
- VM150 Backing Jaw Identification: Each jaw is individually numbered. If numbers become obscured, jaws can be identified by their scroll patterns. Jaw 2 is where the stop screw is located.
- VM150 Back Jaw Mounting Sequence: For easy assembly, all backing jaws are numbered. The stop screw is located below jaw 2. When mounting, orient the chuck so the stop screw is on the left, then feed jaws from No. 1 at the top in an anticlockwise direction.
- VM150 Dismantling: To dismantle, place the chuck back-facing up on a clean bench. Remove the circlip, turn the chuck over, undo the stop screw by jaw 2, and slide out all jaws. Pull off the front plate to access the scroll, which can then be removed from the backplate. To remove pinions, first remove the grub screw holding the dowel, then turn the backplate so the dowel faces downwards. Gently tap the backplate with a soft hammer until the dowel drops out, allowing pinion removal.
- VM150 Reassembling: All components must be thoroughly cleaned and re-greased before reassembly. Place the front plate face down on a clean workbench, ensuring the scroll face (gear teeth) points upwards, then drop the scroll into the body. Place the backing plate on top without forcing it to avoid gear damage; use an allen key to slightly rotate the pinion until teeth mesh and the circlip groove is visible. Replace the circlip. Turn over the chuck, rotate the scroll until the start of the scroll thread is in the number one position. Replace jaw 1, rotate 1/4 revolution anticlockwise, then replace jaw 2, rotate 1/4 revolution, and so on until all jaws are replaced. Rotate the allen key until the screw hole at jaw 2 is visible, then screw in the stop screw, ensuring it is not overtightened.
Jaw Styles and Accessories:
Vicmarc offers a wide variety of jaw styles and accessories to suit different turning requirements:
- Step Jaws: Designed by Richard Raffan, these jaws hold a range of spigot sizes with minimal jaw movement, eliminating the need to change jaws frequently. They are ideal for turning boxes and finishing bowl bottoms by holding the rim without leaving marks.
- 25mm Jaws: Used for expansion into small recesses and firm holding of fine spindle work (e.g., earrings, chess pieces, salt and pepper shakers). For very small articles, the jaws can be unscrewed, and only the backing jaws used.
- Bowl Jaws: Adjustable jaws for re-chucking bowls to finish the bottom or for light clean-up work on the foot. Bowls are held by the rim (internal or external) with 8 soft plastic stoppers. Numerous mounting holes allow flexible stopper placement.
- Long Nose Jaws: Provide better access between the chuck body and the rear of the workpiece. Practical for refastening pre-turned or long workpieces, such as turning serviette rings or remounting rough-turned work.
- Face Plate Rings: Used as an alternative to traditional faceplates, facilitating remounting of prepared blanks directly onto the chuck jaws. Also useful for turning green wood that requires re-turning later. Fit standard jaws.
- Shark Jaws: Feature serrated inner and outer jaw surfaces for aggressive hold. They securely hold cylinder spigots more safely than standard jaws, making them easier and faster than traditional jaws for long workpieces. Available in 48mm to 88mm for VM90/VM100 and 55mm to 130mm for VM120/VM140/VM150.
- Dovetail Jaws: Designed for mounting bowls by expanding into a recess or clamping onto a spigot. The indicated size is the outside measurement of the jaw face when fully closed, with approximately 25mm of expansion beyond the specified size.
- Multi-Purpose Jaws: Adaptable by removing one or more dovetail segments, offering a wide range of expansion and contraction for unique adaptability.
- 3-in-1 Screw Face Plate: Features three alternative diameters (50mm, 75mm, 100mm) for optimum support. Made from K1045 medium tensile steel, fitted with a Glaser screw. Fits most lathes, with alternative thread sizes available via Vicmarc chuck inserts or direct threads.
- Soft Jaws: Acetyl soft jaws allow users to turn custom jaws to suit specific workpieces. These are convenient and simple to use, ensuring the workpiece is true and concentric. They can be drilled, sawn, or tapped. Available in 125mm and 150mm sizes.
- Vacuum Plate: Designed as an aid for woodturning, enabling re-mounting for finishing without leaving marks. It fits directly into a Vicmarc chuck via standard jaws or can be mounted onto the spindle with an insert. Size: 300mm (outside diameter).
- Vacuum Chuck: Precision-machined cast aluminum cylinder with two soft 'o' ring seals for internal or external pickups. Works with the Vacuum Plate and a rotary vacuum adaptor (connected to a shop or domestic vacuum). The rotary adaptor has two ball bearings, allowing the lathe spindle to turn freely while the hose and connection remain stationary.
Warranty:
Vicmarc Machinery guarantees that the Uni-Chuck is precision-engineered from the finest materials and thoroughly inspected. If found defective due to faulty materials or workmanship within 12 months of delivery, Vicmarc Machinery will repair or replace it free of charge. Conditions apply, including returning the chuck with a description of the complaint, purchaser details, and adherence to instructions. Liability is excluded for misuse, carelessness, negligence, or unauthorized alterations. Overseas purchasers should obtain local guarantees from their Vicmarc agent.
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