My local water jet shop was cutting rack and pinion from aluminum plate. Aside from the slight bevel any reason why this would not work even if it was done in 12mm steel plate? Matching gears done on a shaper? I can get use of a shaper for small sizes but longer parts not so much.
Waterjet doesn't produce 90degree square edges so all the teeth will have a taper, had some 12mm aluminum gantry plates cut by a company big in the waterjet cutting industry here in the uk on a fantastic looking piece of kit and I'd say the taper offsets back face by around 0.7mm. I suppose if you angle the pinion to accommodate the taper it might get around it. Another concern would be accuracy as the rack will ultimately define the accuracy of your machine. Waterjet cutting tolerances are not fantastic, most companies will only guarantee within 0.25mm whereas as a common rolled steel rack is accurate within 0.05mm
