So after watching Heat D for Death last night, and having seen the (kind of unfair) number of spinners there, I came away with a number of questions about how these things are put together. We saw Supernova's sprockets getting buckled and their chain flying off, Ironside 3's bar assembly getting bent, and Pulsar's drum seizing up. Obviously there are many different ways to build a spinning weapon, but we rarely get to see the actual inner assemblies of these bots on TV. I was hoping some of the spinner aficionados here could enlighten me:

1) What is the optimal way to power a spinner? Pulsar and Ironside 3 use drive belts (which I assume slip under excessive torque) but Carbide and Supernova use chains. If I remember correctly, Carbide has a torque limiter to prevent the full shock force of the hit from being transmitted back through to the motor, but that makes me think, surely the motor isn't actually useful at the point of impact. Robot spinners aren't like an angle grinder that requires constant torque to spin a very light blade consistently against a material. As far as I know the vast majority of the force imparted comes from the inertia stored in the disk/drum/bar. Is the motor used at all during the impact, or is it only useful for storing energy in the weapon by accelerating it? And in that case, what about powering the spinner with a powered wheel that's pressed against the drive shaft (or a connected pulley). Is there a reason most teams don't use this approach to mitigate shock?

2) What kind of shaft diameter do people use? Having seen Frostbite's puny piece of threaded bar, shaft size surely matters, but how much? Do the shear forces on a horizontal spinner have a massive effect on the shaft? Do they regularly get warped because of this?

3) Sort of still linked to the shaft thing, where do people put the bearings, and what do they use? Many robots I've seen have the bearings at the top and bottom of the shaft, but does anyone have a stationary shaft and have the weapon and pulley/sprocket mounted on the bearings? Are there some special high-force bearings that roboteers use, or are they just regular ones specced for the size of the shaft? Does anyone get away without using bearings on a spinner?

Sorry for all the questions guys, and thank you for reading and answering. Me and a friend are looking into building a heavyweight for Series 4 (if it happens) and now I've got a bit of experience building, I need to start gathering knowledge on heavyweights. Plus I'm generally curious after last night's episode.