I haven't used this a lot, but I do have some comments. I have the Delta DP400 drill press. I bought the mortising attachment from another company not knowing it was also a Delta brand. When I got it, I read the instructions and started to install it. At first I found out that all three bushings that were supplied didn't fit. A couple of pages later I found out that for my type of Delta press, they weren't needed and it fit perfectly without needing one. The manual didn't make any mention of the DP400 model specifically.