A member of the local Society asked me to bring a mirror he's had lying round back to book.
Its a 7 inch f-7 plate mirror 25mm thick. The polish is good except for some gray at the edge.
The problem is its a severe hyperbola like I've never seen. I'm faced with how to attack it to get it spherical again. In the minimal ammount of time as well as needless to say I'll be charging him crumbs to do it.
I can think of 2 approaches
1. accentuated pressure from the edge to .5 tool on top.
This will take a long time given the seriously deep centre.
2. Full tool with graduated facets so more glass goes from the edge and less from the centre. This way it should catch up. I'll then have to recast the tool and go from there.
Any other ideas to fix this up.
Phil b
Its a 7 inch f-7 plate mirror 25mm thick. The polish is good except for some gray at the edge.
The problem is its a severe hyperbola like I've never seen. I'm faced with how to attack it to get it spherical again. In the minimal ammount of time as well as needless to say I'll be charging him crumbs to do it.
I can think of 2 approaches
1. accentuated pressure from the edge to .5 tool on top.
This will take a long time given the seriously deep centre.
2. Full tool with graduated facets so more glass goes from the edge and less from the centre. This way it should catch up. I'll then have to recast the tool and go from there.
Any other ideas to fix this up.
Phil b