Sounds like you need The TOOL. WHich on many surface grinders etc
etc..is a pin spanner or clutch spanner that holds the adapter while
you break the nut off.

I've come to the conclusion I'm going to need a special tool too -
that pin spanner you mentioned. Not sure how to lock the right side
so that the flange can be unscrewed from the spindle. I ASSume it's
screwed on and not pressed on, and I don't know if either or both are
right hand threads or left hand threads. I was hoping someone here
might have replaced the bearings on one of these critters and would
know how to get the flanges off.

I uploaded the photos.

Here's an overview of the head I'm talking about. The head is a model
B923A. I'm not sure why, but the right hand flange is intentionally
about 1.5" farther from the motor than the left side. The former
owner put that brass collar on and it doesn't fit the banjo for the
wheel guards and I want to remove that - preferably without cutting it
off.
http://i749.photobucket.com/albums/x...eadCloseup.jpg


Here's a closeup of the right side showing the two holes in the face
of the flange. The circumference of the flange looks rough, but
that's the rosin I had wetted with alcohol to temporarily "glue" it to
the wood. The metal is still smooth and unmarred.
http://i749.photobucket.com/albums/x...attachment.jpg


Here's what I meant by trying to use 2x4's as wrenches. Even with
rosin on the circumference of the flanges, I couldn't get the wood to
grip tight enough to unscrew the flanges.
http://i749.photobucket.com/albums/x...x4wrenches.jpg

The flanges are soft, so I hated to mar the circumference with a pipe
wrench. I had tried putting a band clamp / hose clamp on the outer
surfaces and then gripping the circumference with pipe wrenches, but
no go. The pipe wrenches on hose clamps was actually the first thing
I tried before going to the wooden wrenches, but I hadn't thought to
hit the flange with Kroil before I did that, so it might be worth a
second try that way.

RWL