It's too bad that saw turned out to be so used up. I think I picked up the same model saw about 2 weeks ago off of Craigslist, the ad had been sitting for more than a month when I finally gave in. Not sure what the 12AS refers to but, I don't think it is a model number. Mine has the same number in the casting, but I found some documentation at Vintage machinery and believe the model number is 3C, 6-3/4" x 6-3/4" and can use 12" or 14" blades.
Interesting that yours has a weight added to the overarm. Mine doesn't have that and it isn't shown in the brochure photos for any of the saws.
Seems a nice size for a shop saw. From the little I've been able to find, these seem to have been in production during the 1950s and 60s, possibly into the 1970s.
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I hope you are able to find something nice, they do turn up and usually are not that expensive. If you are searching Craigslist make sure you search for both hacksaw and hack saw, I've seen many under one but not the other. Same is true for band saw vs bandsaw.
There has been a very nice looking Perkins near me in California for at least 6 months but I think the $400 asking price is way too high for what seems to be a rather small capacity saw. They use the infamous "collectors saw" in the ad so clearly "they know what they have" and won't have any truck with low ballers.
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https://sfbay.craigslist.org/nby/for/d/petaluma-perkins-power-hack-saw/7339847190.html?lang=en&cc=gb
I was looking through old Sears power tools catalogs and it looks like Sears added a 3x6" horizontal bandsaw in 1960. I also have a Kalamazoo horizontal bandsaw which as best as I can figure was made in the late 1960s so vintage and horizontal bandsaw are not mutually exclusive.
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My saw collection is becoming as silly as my small lathe collection, but the saws are at least more practical.