I bought one of these when they first came out (over 5 years ago?) and have used them endlessly for drilling 3 Inch uses holes for mounting rails. Never gets hot. Never had a problem. A bit heavy and tedious to use, but I think it comes with territory. When I bought it it was rated as the largest drill bit on the market and it has stood the test, however it's too heavy for the smaller bits (less than 1/2 inch) as it just smashes them to dust. But you can't go wrong if you're looking forβ¦