I use the quick change model which is great. My student bought this set. I gave him his first project which involved cutting a Nema 1 6 into a 6 box in 2 inch and quarter sizes. I went down to check it out and the bat burned out. I then got a new 2" and tried using wd40 and setting the drill on the lowest setting. Didn't cut. Just my experience with it, others here seem to have had success.