Dave:
On most machines you have to engage the lift rack gear in order for the carriage head to pull the bit out of the timber, none that we've ever sold had it "automatic".
Some do have depth stops, but most don't; you just have to make your own out of a scrap block of wood.
My personal machine is a Swan, fixed tower machine. I got it many years ago at a very low price of $50 from a blacksmith who didn't understand the price or just wanted to give me a deal. It works great and we use it just about every workshop to bore out some mortises.
Jim Rogers
