Hi Bill,
Good questions. Think of a wheellock more like a lighter. Would a smooth rather than knurled wheel on a lighter work better? Probably not. The wheel sits in the bottom of the pan, right in the middle of the flash and the grooves help to keep the wheel functioning against the pyrite after it is all fouled by powder. If it was smooth,it might not grind the pyrite when glazed with greasy powder residue. There is also a hypothesis published Scientific American about 20 years ago, that the wheels had grooves and lateral serrations so that it acted as a milling cutter to cut into the bottom of the pan when the lock was built. That way the wheel fit in the pan was very precise reducing the risk that powder would leak out of the pan. Spark production by wheellocks is a function of a properly hardened wheel, turning with great force against a pyrite held firmly against it. If the dog spring is too weak, the dog holding the pyrite may not press against the wheel with sufficient force to produce sparks. Moreover, if the pan cover simultaneously opens with the spinning wheel, the dog and spring must make sure the pyrite resting on top of the pan cover falls hard against the wheel. Sometimes, the dog gets hung up and does not drop when the pan opens. Some wheellocks had a button you pushed that opened the pan before you fired, but the Lauber has the pan opening automatically upon firing. There are so many things that have to work correctly and be tuned correctly to make a wheellock work. That is why so many guys are frustrated with them. I have several part sets that I've yet to build, but I worked over an Italian-made wheellock that used to be imported back in the 1970s-80s. It is basically Lauber's design, but it needed much work. I polished and re-heat treated almost all the components, adjusted the springs, reshaped the toe of the dog to get it to work right. When done, it reliably sparked like a champ. Currently, one of the chain linkage pins is broken, which were some of the only parts I did not re-heat treat. That lock will be installed on a highly decorated wheellock pistol carbine that I will start in January.
dave