Mark,
The following comments are for others that are considering making a tool grinder.
You have done an excelent job with the changes that I recognize.
Most of us will be starting this project with material from the scrap box to minimize purchacing.
You know, an Engineers work shop is as good as his scrap box.
When changing the design to accomodate other material sizes, unforseen consequences may arrise.
My suggestion is to make a full size sketch with pertinant dimensions recorded.
Its much easier erasing and changing than when its in steel.
Next, when making something with a sliding fit, use the principal of: L/D = 3 or more.
Another words the length of engagement is three times the diameter or width of the slide.
An example of a poor L/D is the lock on the storm door closer, it tilts, jams and is locked.
A good example is a arbor press with an L/W of 4 or so.
Just my 2 cents.
Mark, As far as the spindle is concerned you will not have an issue based upon the skill demonstrated thus far.
The most important point to keep in mind is to press only on the outside race when assembling into the housing.
Then press only on the insider race when assembling on the shaft. This procedure prevents Brenneling the balls in the bearing assembly.
Most spindle designs firmly clamp the bearing at the wheel end in position both sides of each race.
The belt end is allowed to float axialy in the housing to accomodate thermal expansion.
Exterior seals on the ball bearing are in order as well as running in a bath of light spindle oil.
When turned off the oil level should cover the ball at the lowest position.
Keep up the outstanding work!
Restorer