I recently bought an older Jet bandsaw that needed new lower bearings.
Driving the old bearings out with a pneumatic impact hammer was
straightfoward, because I didn't care if I damaged them.
Installing the new bearings was a different story. Each bearing is a
double press fit onto the wheel shaft and into the lower casting, so
you need a way to press the outer and inner races simultaneously.
Because there are two bearings opposite each other, pressing one in
tends to force the other out. I tired all kinds of wierd routines with
clamps, levers, and lots of hammering, to no avail. It became evident
that the right tool for this job is a really big honking bearing press,
which I don't have. Finally, I took the whole lower casting to a
machine shop, and $10 and 1 day later, I was in business.
Oh BTW, my saw has a 4" dust port... in the lower door.