Decent set. The spherical tip does not have a properly sharpened tip. Some have a neutral facet, but most have a negative facet. This means the back of the cutting edge touches the work surface so there is just a lot of friction/heat at the tip and then it breaks. If you can bevel the tip properly before use, spherical tips work well. I used the flat end of a Dremel cutting wheel to hold the tip in place.