Special lathe tools for brass are actually quite reasonable to make. You can machine the tool from a piece of square mild steel and then case harden the cutting end. This means it’s quite easy to make intricate designs as mild steel can easily be machined on the milling machine.
The lathe tool machined from 10mm square mild steel.
The cutting profile is the 3mm half round in the centre. The tool has a clearance angle, but no top rake. Top rake is not need for machining brass.
The image shows the tool directly after case hardening the end. I repeated the process of case hardening 3 times.
After initial use I decided that the tool needed some relief and to achieve this I simply ground it. As you would any normal tool.
The main image shows the final lathe tool. The 3mm half round was used to cut the outer section of the steering wheel for the miniature traction engine. Being able to machine the 3mm half round accurately using an end mill was a great advantage. This would be very difficult to grind without specialist tools.
The roughed out steering wheel. Proof that it is possible to make special lathe tools for brass.
I will use this tool on the other side of the steering wheel and post an article on making this tiny part.