Oct 09, 2003 · Sizing Tips. Sizing and standardizing cutting, welding, and heating tips can be a real challenge because manufacturers assign numbers to their tips that have no relationship to bore size, material thickness, or anything else (see Figure 5). For example, Manufacturer A may call a tip that cuts 1/2-inch steel a Number 1, while Manufacturer B calls it a Number 2, even though both have the same oxygen drill size …