Head clearance can sometimes be an issue. The top of the jaw rails in any vice you would use is roughly 2 1/2 inches from the table. A 5 inch dividing head, which would be appropriate, for these mills is a little less than 4 inches from their centerline to the table. And a rotary table, 6 inch for instance, is going to be about 3 1/2 inches from the table to the top of the rotary head. Of course, there are times when you can fasten the stock directly to the table, leaving a bit or clearance underneath. And keep in mind that using a drill chuck or a boring head will also greatly reduce head clearance. Using R8 collets with end mills or matching drill sizes not so much. Since many of your operations will likely require using twist drills another way to minimize head space is to use an R8/ER32 collet set like this: https://www.ebay.com/itm/36345601769...rchantid=51291. ER collets, by design, have a greater clamping range per collet than R8 collets, and they grip better. Of course you can use end mills with them and not even need a set of R8 collets. Get yourself a set of stubby drills and you can further minimize head clearance.