John;

Tru Turn at  http://www.truturn.com/index.html. Check them out. They make excellent spinners for electric and glow.

And they have fairly fast turn around.  A little expensive, but one of the best.

John,
I have used regular electric spinners and even standard spinners (for the 3 blds) and simply squared off the opening to clear the blade root. I use a small 1/4" Dremel sanding drum in my drill press or electric drill to remove the material. One thing you need to do is mark the opening shape and then sand to that. I clean up the corner with a #11 knife and some 120 grit sand paper around a piece of 1/8" lite ply scrap with the edge rounded to get into the corner.

Best,          DennisT