The grind on the real tool bit can be seen in the first picture. Where it counts, the finish of the cutting edge is very good as it was finalized on one of those motorized diamond tool sharpeners. The picture of the bit by itself is actually a 3D drawing I made for illustration. So, yea, the finish is perfect. The horns are the only parts of the tool that need to be nicely finished.I previously tried a sleeve like that when I was using an aluminum bar for tests. I used spiral thread hose clamps and it was not strong enough. I don't have a welder but I might be able to braze the cylinders on the end.
My tool bit is essentially that design without the center relief and wider. I will reduce the width and relieve the center. I can't believe how clean the grinder is on your tool. Was it done on a tool and cutter grinder or by hand?
Hose clamps are not strong enough. The clamp bits are brazed on the tubing. Brazing, according to one of the manufacturers I talked to is 3X as strong as the parent metal because the braze gets right down into grains of the metal.
Why don't I just publish the entire article here as a PDF?
Please, everyone, do not republish this article anywhere, it is copyrighted by me and is sort of a trial balloon. It is for the readers of this forum only.