High Speed Steel Burs Last Longer, Stay Sharper! These Spearhead brand High Speed Steel bur are expertly crafted in the USA. High Speed Steel (HSS) is a high carbon alloy of steel. These burs are made of an alloy called M2 High Speed Steel that contain tungsten, molybdenum, chromium and vanadium. The alloy is heat-treated during manufacture to a hardness of HRC 63-65. This steel is more abrasion resistant and can with stand the high temperature generated from cutting without losing its hardness. This means these burs can cut faster than the lesser expensive carbon steel and tungsten/vanadium burs. The HSS burs, if used properly, have a much longer life.
That doesn't mean you can't forget to use bur lubricant. Bur lube reduces friction which not only reduces heat, but cuts down on chatter. These High Speed burs also feature standard 3/32" (2.35mm) shanks, and as a trademark of the Spearhead brand, each shank is stamped with the bur's size number. HSS burs are used on precious and semi-precious metals such as gold, silver, copper, brass, aluminum, niobium, pewter and more.
Hart (Bearing) Burs Hart burs (or bearing burs) are similar to setting burs except that instead of having a straight side, they are angled making them great for flush setting and cutting seats in prongs. They come in 45deg, 70deg and 90deg versions. These 45deg (and 70deg) are especially good for cutting channels. Harts burs also have the versatility of not only setting but also using their edges to cut lines like a flywheel. This means that hart burs must be handled more delicately than a setting bur.
This 45deg bearing bur set contains 1 each of 1.1mm, 1.5mm, 1.9mm, 2.3mm ,2.7mm, 3.1mm,3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.2mm, 5.6mm, 6.3mm, 7.2mm and a bur storage box.