Pics of the old style Veritas router table and cross-cut fence. (I must clean the dust of it).
The table top is held by a birch ply frame and has a Triton 3hp router suspended underneath. The Triton is good for such a role as one can wind its collet up above the table height to change bits, which also prevents the router from starting.
The tabletop is 1/4" sheet steel that has a very slight crown so that hanging a large router from it of typical weight pulls the tabletop dead flat. It's stayed that way for 20 years so far.
The fence has many T-tracks built-in and can be reconfigured in many ways by undoing Allen-head grub screws. Various hold-downs, stops and see-through Perspex protection plates can also be mounted. The fence is movable by use of a micrometer thingy reading in, of course - its from North America, thousands of an inch rather than a sensible metric value.
The fence also has a way along the top on which the cross-cut fence can ride. This cross-cut fence too can be reconfigured in various ways; and it takes hold-downs et all just like the main fence. The small block of wood facing end-grain-out is for use as a spelk-preventer when the cross-cut fence is used to make finger/box joints. The block can be rotated or replaced with a new one as its used up over several sessions. It's held by special T-track sliders with wee teeth, pressed into the block by more grub-screws that force the fence parts together.
To make a box joint, a straight cutter (perhaps with a spiral) of the required finger-width is put in the router at the appropriate height. The plank to be fingered on its ends is then held vertically against the cross-cut fence with hold downs riding then locked in the T-track; and the work piece is positioned for each cut by opening the small metal fingers to the finger width then using them to index the sideways movement per cutting operation, as slots are cut one at a time to leave the fingers.
There's a set-up process for placing the initial cut and getting the finger/slots width exact. Its possible to make softwood slots and fingers that are a tad too tight as softwood squashes so the resulting jointed corners are very hairline-jointed with ne'er a gap. For hardwoods, the gaps and fingers are set to an exact width - a couple of thou change is possible using the main fence micrometer adjuster.
Once the thing has been set up, one may batch process as many box-sides as needed. They'll all match and be gap-free. There's no spelching or other breakout if the backing block is used, a spiral bit is used and the passes of the workpiece over the cutter are made at an appropriate rate. One's own fingers and hands are well out of the cutter path. The hold downs attached to the cross-cut fence will hold the work piece firmly in place during each cut.
