|Tungsten carbide cutting wheel.
The Boeing aircraft company operates a wonderful surplus store in Kent, Washington (near Seattle). These three slot cutting bits (6-8 inches in diameter) are not saw blades, they are used in horizontal milling machines to cut grooves in metal, similarly to the way a dado blade works in a table saw, but more expensive.
The one standing up in front is the fanciest, each tooth is an individual block of tungsten carbide, used for cutting very hard or abrasive metals. This one would stay sharp for a very long time cutting aluminum, or a decent interval cutting titanium or steel. The other two were kind of a mistake, I meant to buy only carbide-tipped ones, as tungsten samples, but they were coated in protective wax and I didn't look closely enough.
The fact that they were in wax, which is how they are generally sold when brand new, is somewhat odd since they were being sold at scrap prices (a few dollars per inch of diameter). Perhaps the Boeing company is so organized that when they put used bits into storage they re-coat them with protective wax.
Source: Boeing Surplus Store
Contributor: Theodore Gray
Acquired: 11 August, 2007
Text Updated: 11 August, 2007