I made an extension rod for one of my countersink drill bits. The shaft diameter of the countersink was .375. I used a .750 A36 rod that I turned down. I bored a hole to fit the countersink and turned the rest of the rod to .375 to fit on my drill. It was 8" long. I needed it for one of my applications to use on a drill. It worked but the finish was downright ugly. I used a HSS cutting tool. My lathe is a LeBlond Regal 13x30 (3hp). I think the first mistake I made was boring the hole first. Probably should have done that last to utilize a live center for the turning process. The radius on the HSS cutting tool was probably to small. Any suggestions. I am definitely a newbie.