The bearing ID is 8.13mm.  The shaft OD is 7.89mm.  So I needed something to make up that difference.

I went through all the rolls of tape I had around, and found one where exactly one wrap of tape, not overlapping, would make up the difference.  Worked, until now.

The steppers running at the higher current get a little warm now, and I didn't hook up an enable pin on the drivers, so they are always on.

Over the course of the last couple days, I've run them in and out a lot, and eventually an axis got 'rough'.  The adhesive had softened and the tape squirted out so the shaft was flopping around.  Another axis showed signs of failing soon...

Tried in vain to make some heat shrink work.  It goes on, but it never compresses evenly and so the shaft is always wobbly.

Then I tried AL foil.  Perfect.

It takes about a 180mm long strip of foil, about 8 smooth and flat wraps, to make up the gap.  I end the wrap right where it started, so it's also perfectly centered.  I feel much better about 8 wraps versus the one I had before.

There was a learning curve as to how to keep it from un-spiraling when you pull the bearing off though.

Basically, leave some extra and peel from the middle out to the edge... and then compress it.  It mushrooms down onto the surface and keeps the whole coil in place.

Pics later.  It's a tedious process taking about 5-10 minutes per bearing to do it right, but it's the only way I'm using these shafts without runout.

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The foil has worked well, with the exception of one where it also squirted out the end.  One drop of superglue fixed that.  I went back and did all the rest.

</EDIT>