I seem to be having problems drilling small holes in 0.5mm silver sheet. I am drilling by hand with a pin vice and a 0.6mm drill bit but when I put pressure on the pin vice the drill bit slides up straight away. I screw the pin vice really tightly to hold the drill bit and there is no movement until I put pressure on it. Has anyone got any ideas why it's doing it and what I can do as its never done it before