The key thing you need to look at is the spindle travel. Most drill presses you will see at Lowes or Home Depot will not go deep enough. I have a bench top craftsman, and no it does not go deep enough to install the thumb mold that I use from Buddies. So - how to get around this? I drill my thumb as deep as it will go, then loosen the chuck and drop the drill bit lower. It's certainly not text book, but it does work. Typically when I hit the weight block I will get a bit of drift which leads to using a bevel sander to get the bottom of the hole big enough for the mold to fit.
On a side note, I would not recommend using a plug cutter on a drill press from a hardware store and a bolt on jig. There is just too much vibration and you will damage the ball. I use to use thumb slugs before I went to the molds from Buddies. I would just drill the 1 1/4 hole, install the slug, and then use a router to cut the top off to about 1/8 above the surface. At that point I would drill my thumb. After that, use a box cutter to remove the remaining slug that was above the surface. Good luck!
