Mendit,
I'm assuming that all of your customers are stupid and you know more about motors than they do, Right? I don't think that my tolerances are too tight, I'm just trying to meet a customer's specification with some kind of acceptable capability in our process. This is not a NASA project but one that requires very close tolerances. And with most standard manufacturing practices, I agree that this may be impossible. I've got a shop full of standard manufacturing practices and don't have the equipment that I'm asking for here. Most of us are still in business today because we've given the customer what he asks for. And we all know that customers can be a little ridiculous in what they ask for sometimes. But when your customer asks you to meet a specification and show that you have process capability with Cpk's to prove it, what should your target values be? I know all of us have seen customers requesting tighter tolerances in areas of vibration and efficiencies, this is just another case where they feel it is required. If I want the business (and the 60% GP), I'll have to show the capability or somebody else will.
MB