I finally built a prototype of a marking gauge with a cutter wheel out of some scraps.

https://lyse.isobeef.org/tmp/streichmassprototyp-mit-messerrad/

It had been a long time in coming, I bought some replacement cutting wheels three years ago for exactly that purpose. I also found out that I need more M3 countersink bolts for future marking gauges that I want to make (maybe two or three more). Luckily, I had exactly one. I thought I got way more than that, but M3 is very, very scarce in my collection. My M3 bolt was barely long enough to attach the cutting wheel to the bar. But it’s okay for the prototype.

I was pleasantly surprised that I managed to drill the 2.5mm diameter hole almost perfectly in center in the 8mm diameter aluminium round bar. Center finder, drill press and vise with a vertical prism for the win!

I knew upfront that the M5 steel bolt to lock the bar in place definitely needs to be replaced with a brass or aluminium one (maybe with a knurled head). Otherwise, it cuts into the aluminium bar and leaves ugly marks. These burrs might even scratch the workpiece. But, of course, I don’t have any brass on hand either. Alternatively, I swap out the aluminium bar for a steel or even stainless steel one. Stainless might be tricky to precisely drill and tap, though.

I already learned a few things by making this prototype. The final wooden fence can be even a bit bigger. This round thing behind is also too short, I’d like it to be a tad longer and thicker. The final one will be made from hardwood, not spruce. Other than that, it’s great and already more practical than my store-bought marking gauge with its round fence. This only causes the tool to roll around on the workbench. Or even roll off. Stupid design.