I've been playing around trying to get a system sorted to remove material from the non drive side end of the alloy carrier in shimano cassettes. A lathe would do it, but i dont have access to a lathe - yet!
It struck me that using commonly available and cheap facing tools may work. After all the material is soft aluminium.
After messing about today trying to centre and keep the cassette level, i think i have a system sorted.
The end results are not perfect, but WAy better than using the end mill in a pillar drill and a dremel with a grinding head.
It would have been neater but my first iteration (see flickr for more) didnt keep the cassette level. Oh well.
Unfortunately the alloy carrier design for the slx and ultegra 9 speed (cs6500 series) cassettes has the spokes that actually carry the cogs protrude from the inboard end of the alloy carrier, which limits the amount of material you can remove. The xt (m770) have an alloy carrier that allows a lot more material to be removed from the back, meaning it can be snugged much further inboard, and allowing 6 (maybe 7? see walt works...) speeds to be fitted with 9 speed spacing.
However, with a bit more work i would have a very passable 5 speed with a good range, say: 15-18-21-24-27 as an alternative to the 17 - 34 of the 6 speed xt or perhaps i could use the M770 18-21-24-28-32 with a 15 or 16 king cog.
Why all the fuss? options! The jones may very well go 5 or 6 speed at some point and i am limited to a 34 tooth middle ring maximum unless i use a double front set up, or am willing to put up with a rubbish chainline. It also gives me options for the Vertigo.
Also its fun...there we go.