Adjustable Router guide.
This guide will allow for holes from a tiny 20mm Diameter to a massive 760mm diameter (when using a 6mm bit).
The best part is not being limited to preset sizing as you can set it to any size in between.
(Seriously, I wish I had one of these years ago when I started making my various speakers).
Made out of 16mm thick 9 layer ply.
Supplied with a wooden handle, aluminium pivot slide, zinc plated nuts and bolts.
The un-drilled base allows for mounting to any number of routers, from 1/4" to 1/2".
The guide is 51CM long, 10CM wide at the narrow end, and approximately 17CM wide for the router mounting area.
It does NOT come with instructions.
So here's a quick guide for you.
Place your router on the upper textured surface of the guide.
Center the spindle over the 50mm hole and position the routers handles to line up with its length.
Mark and drill holes in the guide to suit your routers base plate.
Counter sink the mounting holes in the guides bottom (Shiny side) so that the screws won't catch or drag across your work piece.
Mount the router with the provided counter sunk machine screws and nuts as needed. (4 of each provided).
Mount the timber handle (It has a pre-drilled hole on one end for the screw) to the top side of the guide with the supplied single counter sunk timber screw from underneath (Shiny side).
Undo the two wing nuts on the aluminium slide assembly and remove the shorter aluminium piece.
Place the longer piece into the slot in the bottom of the guide with the two threads going through the top of the guide.
Put the short aluminium plate on the top of the guide over these threads and put on the two wing nuts.
That's it. Your ready to make holes :)