How would one go about attaching a high strength axle to… well, anything, really. They’re certainly too big to use with any structural elements, unless a larger hole is drilled of course.
There are high strength bearings, and the high strength gears can work with the high strength gears. Bolt some C channel to this gear and you’re done.
You can also get High Strength Lock Bars, to reinforce gears so the don’t break if using the HS Shafts to transmit torque, and you can use them to bolt shafts to channels without using gears. Most teams do find themselves drilling larger holes for the shafts to pass through, then a HS lock bar can be screwed across the hole to connect the shaft to the c-channel.
HS lock bars can be found on ebay, amazon.com, robosource.net or here http://www.technology-education-resources.com/media/d28e7d12b0a2c4d3ffff800fffffe417.pdf
How can the axles be used so that they are freespinning?
There is no way to free spin a HS shaft on a gear. You would have to mount them on an axle and free-spin the axle in bearings.
And drill a hole in the structure the bearings are mounted to, yes?
That is the most common thing to do. But somewhere in the documention, VEX mentions that the pre-cut HS axles (2" 3" and 4") are a millimeter shorter than the hex-standoffs of the same size, so you can build an assembly of c-channel spaced by standoffs, then trap a HS shaft between the c-channels in HS bearings on each end, thus eliminating the need for shaft collars.
Very, very interesting. This is for sure something VEX has done right.