[Steven Smith]

We have a CNC router, and we love it. It is quite a bit more rigid than a ShapeOko, but not nearly as rigid as some of the "built specifically for aluminum machines" some teams have. Just understand there is a learning curve as you get to know your machine and what tolerances it has.

For example, if you want to do a drive rail, you need a way to mount it to the bed to mill. You need to do this perfectly square to the direction of travel, or your holes (lets say, bearing) will be shifted to one side of the rail or the other. You either need a bit that can reach all the way through the tube to mill both sides (many don't reach, you need to run small diameter bits at router speeds, but the deflection on a 3/16" bit with 1.25" of stickout starts adding up). If you flip the rail, you need a way to maintain your index, and your error can get flipped as well, so if you were 0.010" high on one bearing, you could be low on the other, leading to a non-perpendicular shaft. IMO this is worse than having one that is a few thousands off in the X/Y direction on a rail, but milled through square on a manual machine.

Long story short (and that is just one of MANY personal experiences with a router), it is an amazing tool, especially if you have a fingerbrake, but it isn't magic. Don't expect to hold gearbox/bearing tolerances out of the box with little experience... but I still recommend getting one eventually. Many people recommend CNC plasma, which does have some advantages, but I'd argue the disadvantages over a router stack up for an FRC team. If nothing else, the ability to do polycarbonate (which is underutilized by many teams).

I struggled with wrapping my head around "why lathe" too... However, I spend more time on my lathe than my mill. Even in a gearbox, you focus on the plates, but having standoffs between the plates, stepped shafts to hold the gears, yada yada... all really nice to have. For basic lathe work of center drilling ends of shafts, turning down 1/2" hex, etc, a cheap $500 HF lathe isn't a bad place to start.

Rotary broaching is interesting, but I think you'd be happier with an arbor press and push broach. You need an arbor press anyway to press in bearings if you don't have one already.