why not just drill on the lathe?
a couple good reasons for that. You want to drill a lot of holes real fast, a press is much faster. Another reason would be that your collets get all gummed up and full of dust and crap that needs to be cleaned out if you want them to still be any good. A final reason would be that a vise can potentially offer a longer distance of support to the sides of a blank. A collet or set of pin jaws is only so long..like a set of ER-32 is only an inch or so deep. When the blank is beyond that distance, there is absolutely no support around the blank, so now you have to pull the blank forward or risk a blow out. Sure..you can start with the blank further out from the collet, but then you just reduced your accuracy, so now what is the point? If you drill on a lathe and do it properly, it is not the most accurate way to drill a hole. It all comes down to how well tuned is your equipment? If the tail and head are mis-aligned, then you will not be true. If the table and/or the vice are not square and secured on a drill press, the hole will not be true. There are more advantages that I can think of to use a drill press than there is for a lathe. The only lathe advantage I can think of is if your center of the blank is not the same at the top as it is on the bottom..in which case you can use a drive spur and a live center and put the points where you want them and then spin the blank round, which would then manipulate the center to be in the center..but even now that you did that..you can get just as good a hole out of a drill press. Everything comes down to tuning your equipment..it always just does. A drill press is a lathe standing on end...think about that.