I give up. I've tried to explain. It would work. Makes no difference. I'm going to make the jig and use it. I'll end up with a whole bunch of 4" coasters that won't need much sanding. But, at some point I will also make a hole saw with a retractable center point. And, Who knows, I might get rich. Lol.
Oh, JT, I have a whole bunch of hole saws. Remember, I sold tools for a lot of years. I do know how to use everything I sold. If you can grasp the concept of an automatic center punch, it's not that much of a jump to what I'm talking about. No matter what, I know what I'm envisioning.