I have a bunch of jobs that require long reaching drills, not necessarily long fluted or deep hole drilling, but long length of reach. For example, a large diameter square tube that requires a hole in the top, and a hole in the bottom, but space between. Our traditional methods of doing this are slow, generally using a 2xD drill to make the first hole, reaching through the hole with a center drill to spot the bottom, then using a 7xD drill to make the bottom hole. Generally speaking, the reason for this is that using the long drill alone causes wobble and out of tolerance holes, broken inserts, etc.
I seem to remember from my trade school days, paging through one book or another, and seeing drills that were ground with a center drill style tip, and then the full diameter a step lower. I'm thinking I could have some carbide drills custom ground in this fashion at the lengths I need to reach, and eliminate a couple extra steps.
Anyone know of a tool profile like I'm thinking of?
MSC Industrial Supply
I think what you are needing is an indexable pilot full flute step drill.HTH