Monday 9 July 2018
Using a router on the lathe gives countless opportunities. There are several jigs, fixtures and attachments on the market to perform complex operations on the lathe with a router. You can produce single and multi-start spirals, decorative grooves, uniform depth and fading, parallel to the axis of turning or in any angle to that. The possibilities are only limited by the user's imagination.
Some of these require specialist jigs, but some decorative effects such as straight flutes, reeds, incisions – whether full length or stopped – can be produced relatively easily with a simple jig and a router, and this is what we are going to make here.
Background of the router jig
Routers, sometimes considered to be the most versatile woodworking power tool were first invented about a hundred years ago to do the job of the traditional moulding planes for edge decoration – moulding – of timber. These were heavy stationary machines. The router, as we know it today, appeared about 50 years ago with the advance of the mass production of small, light, high-speed electric motors. Routers, with an abundance of cutter shapes opened up possibilities for the woodworker never experienced before. Using them to add follow up decorations to turned pieces was an easy and logical step and numerous jigs and fixtures became available to provide the woodturner with this new approach. Decorations can be applied both axially – on the outside of a cylinder or a sphere – or radially on the face of a platter or a disc. Both types of applications can be concentric with the object, even depth cuts, or they can be off-centre, fading away at one or both ends of the router cut.
The router is mounted on a rectangular cage which is fixed to the lathe exactly parallel with the main spindle. The 50 x 22mm fillet – at the bottom of the photo – fits between the two bed bars. A circular cut-out, 105mm diameter gives a good clearance over the chuck. Just behind the circular cut-out, the hole for the M10 bolt can be seen which fixes the whole assembly to the lathe
A similar but smaller cut-out – 80mm diameter – gives plenty of clearance for the revolving centre mounted in the tailstock. At the top of the cage you can see the mounting rods of the router. The location of these two rods is very critical. The distance between the pair of them must be identical to the distance between the two holes in the router base. This is absolutely essential for the router's free and easy movement
There is something different about the two mounting blocks at either end of the two rods. One end is mounted on a good quality, solid hinge
The mounting block at the other end is fixed with two wood screws. By undoing these we can place washers on the screws which will put the router on a slope. Without the washers the router will move parallel to the main axis of the lathe and it will produce parallel grooves. With washers inserted the grooves will fade away. The hinge at the other end allows the rods to deviate from their original plane. You can make the screw side of the cage a few millimetres shorter and use washers even for the horizontal setting. This way you can fade the grooves in both directions