tom:

IMO, there are three sizes of teeth, fine, medium, and large. I know the size of the teeth has been attributed to the wear on the wheel used to make them. Less wear small teeth, more wear large teeth. I don't think that is 100% accurate, and this is why - According to Pete Hamilton, you could request "small teeth" on your knife in the past.

Note: it also seems that short bladed knives most often had smaller sized teeth with larger teeth reserved for larger blades. Not really enough real estate for large teeth on a short blade. Not saying you won't find one, but medium teeth would be more common of that vintage. Newer pieces seem to lean towards larger teeth.

Most of the early teeth on 18's (and 14's, 15's) seem to be of the fine to medium (standard) size. As the 60's wore on, the variation in size seems to be all over the place, with larger teeth becoming more common. I believe this is partly due to the time required to grind the teeth. More teeth, more time.

Years ago I would measure the TIP (teeth per inch) on various blades. I kept track of quite a few pieces for what reason I don't know, but eventually lost interest. Don't know where the paper record is now.

On the subject of small teeth being an "option", I recall most if not every model 1 with teeth being in the small to fine category, which for all practical purposes holds true to this day. So is grinding wheel size the only factor determining teeth size? It doesn't appear that is definitively the case, at least not in the 60's.