A router duplicator (also known as a router copier, copy carver or wood carving duplicator) is a machine that uses a woodworking router to carve 3D wooden items. The principle is very simple. A router is attached to one side of the machine and a follower or stylus is mounted to the opposite side. The router and stylus are fixed to the same axis so they will always move in unison.

The item that the user wants to copy is known as the master. (This master could be almost anything, i.e. a gun stock, guitar body, a table leg or a propeller.) This master is fixed to the stylus side of the duplicator and a wooden blank is fixed to the router side of the machine.

The user then follows the contours of the master by manually guiding the stylus tip over the master. The router follows the movement of the stylus and copies/carves the shape of the master out of the wooden blank using the router’s cutter. To make this process easier, the weight of the router is counterbalanced, and the stylus tip (which is either the same dimensions as, or slightly larger than, the cutter) is made of low-friction nylon. Different size cutters and stylus tips can be used during the carving process, larger cutters for roughing out and smaller cutters for channelling and final finishing.

Most router duplicators are designed around the same principle. A U-shaped jig/carriage which is attached via linear bearings to a bearing rail, allowing the carriage to pivot (much like a seesaw or teeter-totter). This rocking action is equivalent to the plunge action of a router. The carriage can also be pulled and pushed along the length of the bearing rail, this action is for cutting along the width of the workpiece. The main router assembly, linear bearing and bearing rail are mounted to two additional horizontal rails, attached via linear bearings or rollers. This allows the main router assembly to travel down the length of the workpiece carving as it goes. This basic yet effective design allows for 3 dimensions of movement.

When a woodworking router is attached to the duplicator the router is freed from its usual constraints of being hand held or fixed to a router table. This turns the router into a versatile wood copy carving machine capable of carving many 3D wooden items, such as guitar bodies, propellers, gun stocks and furniture components, to mention a few.

What makes a good router duplicator?

To build an accurate and safe router duplicator it is important to use suitable materials such as steel, aluminium, or a mix of both. This will reduce flexing and increase stability as well as help resist the forces from the router when carving. This is especially true when using a powerful 1/2″ router.

As linear bearings are an integral part of a well-built quality router duplicator, it is important that the bearing be bolted to a flat surface in order to run smoothly. This is why the Clone 3D and 4D duplicators are constructed using tooling plate which is machined both sides to high tolerances, ensuring a perfectly flat surface and subsequently smooth operation.

Adjustable and proper counterbalancing of the router and router assembly is crucial to a positive user experience. A poorly balanced duplicator will feel unstable and twitchy to use, causing user fatigue.

Single Pivot Design Duplicators

Due to the simple design, a single pivot duplicator has few moving parts making it robust, reliable and straightforward to use. However, one downside to the single pivot design is that when the router moves downwards the cutter does not move down vertically, it follows an arc. This is not normally a problem when carving the outside surface of an object, especially when using a round nose cutter. However, when using a flat bottom cutter (when cutting channels, slots and inlays) it can be difficult to carve right up to where the bottom of the slot meets the sides. This material will then need to be removed using a chisel.