Hello!

Is it possible to have two toolpath previews on one screen (X-Y and Y-Z)? If not then how to set it to Y-Z direction? I use Mach3Screen V1.59a.

Regards, Denis

You can't set the toolpath to a specific orientation. You can probably have two, but you'd need to manually rotate the views each time you started Mach3. Although you may not be able to change them independently.
Keep in mind that having two toolpaths might actually slow Mach3 down considerably.