Hi Walter
Yes, most machines I've seen are of the nut-on-thread variety. This machine is unusual in this respect.
I believe this to be an Apex Model A3, dating from about 1922, though I'm not sure how long they were made for.
As far as buffing is concerned I only spent about an hour hand polishing it with Autosol and was surprised how well it came up.
I have got a buffing wheel, which is only a 6" size, adapted to use on my 6" bench grinder. I fitted the supplied arbor to this, which was a little difficult to centralise and used it recently to buff up my Columbus Upright. Although it did a good job, the green polishing stick supplied seemed to quickly clog up the wheel and on some occassions left deposits on the casing, which had to be cleaned off again.
The main reaason I didn't use the buffing wheel on the Columbus was because I didn't want to have to remove the rivets holding the nameplate on the motor in case I damaged the badge by polishing over it..plus I figured that by the time I'd cleared enough space to move in the shed I would have got on quite well by hand!
One of the good things about hand polishing is that you can keep on doing a little bit without taking the machine to pieces.
I also have a Kirby Handi-Butler attachment but unfortunately the flexible drive coupling assembly is damaged at the handle end.
Stephen