Need help reducing shaft diameter

[gwin99]

Hi, so my team recently found ourselves drastically overweight. To shave off pounds, we need to replace our steel shafts with aluminum. However, the aluminum rods we got (because McMaster Al shafts were $60 each) are 4-6 thousandths to big, and don't fit our linear bearings. The shafts are to long to turn down without wobbling, and we've tried hand sanding and belt sanding with no success. We've also tried turning it and using sandpaper, which seemed to work, but a less dangerous solution would be welcome.