Dying wheel, or not enough patience?

The answer to the question is how much money do you want to devote to the hobby. I like to cab fast and when a wheel takes a lot longer to complete a task, I replace it. I use a Nova 220 and it takes the 220 scratches off faster and can also take it from blocky to round.No problem going from 220 Nova to 600. I over use my 220 and it will be first Nova I replace from the set.

About a year ago I was having the same problem Ronda. I don't remember if the scratches were confined to the dome or not, but I replaced the 280 Nova wheel and the problem disappeared. My old wheel was a little over 2 years old.

I generally do not replace a nova wheel until I see some spots showing on the surface of the wheel where the diamonds have worn off completely. These will look like worn black spots. It is true that as you use a nova wheel for quite awhile the surface of the wheel becomes slicker, and a 280 will actually grind less aggressively and act more like a 400 wheel. However, I have repeatedly gone from a hard diamond wheel to a worn 280 and still never had a problem with scratches. Since you are having problems with the scratches only in the center of the dome, this tells me that the problem with the scratches is not because of the nova wheel. There is a very simple solution to getting rid of the scratches in the center of the dome on a cab, or even getting rid of scratches on a flat polished piece. When you are polishing the dome of the cab, you need to hold the cab at an angle to the Nova wheel and sweep the center of the cab across the edge of the wheel, allowing the cab to depress the very outer edge of the wheel. The outer 1/8 inch of the wheel should literally sweep across the entire face of the cab. Because the edge of the wheel is flattened in this motion, all of the domed center of the cab will come in contact with the wheel. It will only take about 8 or 10 passes across the edge of the wheel in order to get rid of the scratches. I will admit that it is a little tricky at first to figure out how to hold the cab in your fingers as you do this maneuver, but once you get the knack of it, it is really easy. Using a dop stick (which I never do) would make it even easier to hold it at this angle. You will need to do this with all the other nova wheels as you move to finer and finer diamond wheels. Here is a photo of the angle that the cab should be to the edge of the nova wheel:



If you have all the nova wheels you need, for example 280, 600, 1200, and 14,000... and you use this "sweeping the edge" motion correctly on each one, I absolutely guarantee that you will not have any scratches on the center of the dome. This will work on small flats, too.

By the way, those are not my hands in the photo... I hired a stand-in with gnarly fingers to hold the cab.