Even if it's just a bolt?
You can try it without but usually if you don't ground them you get a lot of noise. Do you have a metal tailpiece? If so, ground that instead of the bolt.
I thank you for the video! I changed my mind and will use a fret wire on top of the bridge instead of bone.
As mentioned, you will get hum through your amp until you ground the strings with your hand/fingers, if you don't run a wire to anything that contacts the strings like the bridge or tailpiece. You will of course need a metal saddle on a wooden bridge. Or use a metal bridge.
Thanks everyone!. I'm using metal (rivet) string retainers through the bottom of neck so I can run a wire from a rivet where it goes through the neck to I guess the one of the 2 pots. I am using a wood and fret wire bridge .
Here's how to do that...
Thanks a million John! I will use this method.