Needing to do some circular routing and anxious not to reduce the available depth of cut, I decided to build my own, based on the fine adjustable router fence.
Having found that the existing fence bars had acquired a decided curve to them I replaced with 3/16th Silver steel rods.
An offcut of oak floor board provided the timber and determined that 6mm T-nuts would be the largest I could use.
Without access to a pillar drill while my workshop is still being built I ensured the alignment of the holes by using my 8mm Joint-Genie since the outside diameter of the T-nuts corresponds. The fractional difference between the imperial bar size and the metric holes I judged would allow a reasonable slip fit for initial crude set up but did introduce an unforseen problem which had to be addressed later.
The 'fixed' (inner) bar was made a little shallower than the moving bar (which has the tramel hole drilled in it) in order that it would not foul the timber being cut.
I decided that the hex head on the adjustment bolt would be too awkward to adjust so I doubled it up with a wing nut, held in place with a Nylock nut to provide some more substance then made a knob out of epoxy putty (milliput white)
The 6m hole for the adjustment bolt was positioned again using the Joint-Genie but using a T.nut with the prongs removed and carefully drilled out to 6 mm as a bushing. The bolt was then attached to the 'fixed' bar, as a rotating ,by use of Nylock nuts and washers on either side of the piece.
The limited thickness of the bars was found to cause two of the T-nut barbs to slit out the edge of the timber but removing two of the barbs and adding a small amount of industrial strength superglue to further secure the structure.
The initial build resulted in this:
Two problems immediately became apparant:
The Nylock nut protruding from the fixed bar just prevented cutting the smallest of the diameters I need to cut.
The discrepancy between the imperial bar and metric hole allowed the construction to rack.This was probably compounded by the fact that the fence rod holes are lower in the timber than the adjustment bolt to allow for the bulk of the knob.
Drilling out to half the thickness of the timber to sink the nut easily corrected the first problem.
The second problem I found to be very largely alleviated by carefully drilling two 4mm holes at the same height as the adjustment knob to hold two 4mm diameter nails superglued into the fixed bar.
So far it's working a treat and I'll post the results of my labours just as soon as I've finished.
Ray
ps Swapping the moving bar for a deeper one without the pivot hole would produce a second fence useful for centring mortices or edge grooves in a piece.
R