Review on Sunex SX545B 8 Inch Reversible Right by Ryan Sandell

So for such a great thing I have a Sunex HD 800rpm and this drill bit chews metal much faster than the Sunex 800rpm (don't know why, it has to be RPM). I'm building a very large mechanical structure and drilling a lot of metal up to 1/2 inch and sometimes more. I don't know durability. mike