With all of the machining on the front of the hub finished it's time to switch to the back. The hub is flipped round in the chuck and checked again with the dial indicator. With the live center supporting I machine down the back of the hub. I've used the radius tool on the back as well.
All that material in the center isn't provinding a lot of strength to the hub so it's bored out. Plenty of swarf on the lathe, time for a clean up.
More careful measuring and machining produces the bearing seats for the inner race and a seat for an
oil seal to keep the grease in. I've also machined slight tapers leading into the recesses to help guide the bearing cup and seal into position.
With another piece of ground tool steel I've tapered the back of the hub down to where it slides into a cup attached to the spindle. This is designed to keep dust and dirt away from the seal. There is a lip machined on the edge that flings dirt away from the hub it also stops any grease that escapes from migrating up the hub towards the brakes.
