That wheel was untreated smooth wood but wood treated with a soft cello string resin produces a better 'rasping sound'. I also use a cog shaped wheel which creates a 'plucked' sound. I believe Russolo experimented with many treatments on the wheels and strings.
Is the wheel, that rub the string, made of simple wood? Is it smooth or scratchy?
That wheel was untreated smooth wood but wood treated with a soft cello string resin produces a better 'rasping sound'. I also use a cog shaped wheel which creates a 'plucked' sound. I believe Russolo experimented with many treatments on the wheels and strings.