There are a few jigs that you can attach to your grinder that produce consistent and perfectly sharpened chisels. Most are made in the US at a reasonable price but the frieght costs to Australia are huge. The few jigs sold in Australia are over $100 and range towards the $200 mark.
The design I came up with is very similar to the Oneway Wolverine jig. Many turners have made wooden versions of this jig but I decided to make a steel version. It cost me around $50 to make.
Step 1: Design
Some 30mm square tubing would be attached to the board/stand the router was mounted on. A 25mm square tube would slide trough the 30 mm tube. A threaded knob would then lock the 25mm tube in place. Since I wanted to change the end pieces of the jig a similar system was devised. Initially the locking knob was to be on the side but I wasn't sure and so the final product had 3 different positions for the knob.
I was worried about too much movement of the 25mm tube inside the 30mm tube. Ringing a steel supplier I found out that the 30mm tube comes with a wall thickness of 2mm that leaves a 26mm internal size. Only 1/2 mm gap all around, that's a resonably close fit. Also since the sqaure tubes have a weld on one wall and may not be perfectly square you can get a fairly tight fit.
The whole design uses only 30mm square tube, 30mm angle, and 25mm square tube.