The cutting edge

After reading some more on vacuum technique, the soldering of the RVS didn't look like such a good idea anymore.
If I want to bake-out a chamber, the melting point of the solder is just too low.
So I tried heating the whole RVS hemisphere in a coalfire (pumped with a leaf-blower).
The temperature was ok to almost melt the 60-40 SnAg solder (600 deg.C), but it didn't flow.
So after that experiment failed, I tried the grinding machine, after making an edge I continued with sandpaper, whetstone and then polishing.
It worked! I now have a smooth edge and I can use a standard viton ring.