When rough grinding I have experimented and is satisfied with the new tool where I grinding on an iron-plate. Next time I grinding a miror I will get a piece of iron bar. I have linked 75 seconds movie from the rough grinding-proces. I’m using the method described by Texereau and Howard, the file take up 6 mb.
Movie: Rough grinding
Here is some pictures from the rough grinding:
The sagitta (the hollowing) of the mirror is controlled by the slide caliper.
The curvature is controled by a template.
Adding water and grinding powder to the mirror.
The grinding realized by chordal stroke.