Extremely fast mirrors

Can any of you experienced mirror makers offer any tips or suggestions on making f/2 or f/1 spherical mirrors? I've tried a couple both by hand and machine. It seems that the only way to get an even sphere going without zones is to use a spindle machine with both the mirror and tool revolving quickly. TDEs and other wierd things still come up and haunt me. Any tips? (size of tools, overhang, stroke length, pitch or polishing techniques, etc.) MANY thanks, Bob Piekiel