Luger Frame Tooling Marks Study

[Ron Wood]

Originally Posted by CJS57

Can anyone explain how Erfurt machined the blind ended square cutout shown in the very first post? The DWM circular end mill process is obvious. But for square corners like Erfurt, a square broach usually needs to go completely through the workpiece?

The apparent square cutout is an illusion caused by the lighting. The square end of the cut actually stands proud of (above) the milled out area behind it.