..mine sharpens up to 1/2 inch....and you can buy a small attachement to hold and sharpen 3/4" bits for about 40 bucks. You can also sharpen, or make, split bits to.
Its an easy tool to use but I must admit, after "playing" with it a couple days I am much better at sharping a bit and knowing what I'm looking for and trying to do. You know,the "chisel" the angle, standard or split bit ect. Heck, I know more now about drill bits than I ever thought I'd need. It all makes sense to me..... Now

AND it's a good idea to watch the few minutes video that comes with it!!
...and finally, I think, MY bits that I sharpen cut better than some of the "assembly line" bits.
Thanks for you tip,Pete.