Its a machine for producing flat surfaces and slots and keyways mainly. You have a big solid dove-tailed thing at the top which goes forwards and backwards with a cutting tool mounted on the front. A machine table is fitted underneath and as the tool goes back and forth the work is slowly feed sideways to give a flat surface. A milling machine will do it much quicker, but with skill you can get a beautiful finish with the shaper plus you can grind your own tools easily ( single point - very similar to a lathe tool ). They are great for cutting internal keyways where a mill just cant get. These days universal mills aften come with slotting attachments ( which are like a mini shaper ) for such jobs.
It doesn't do much at all without being set up....
It basically does for plane surfaces what a lathe does for round ones. You can cut V-blocks, keyways, both internal and external, gear teeth, slots and T-slots, smooth up and flatten surfaces. Just about anything a horizontal mill can do, it can do and with cheaper tooling. It's just a lot slower. If you get into it, you'll use it all the time. Most shapers just sit and collect dust.
As to what it's worth, a lot depends on condition and what comes with it. It sounds like there's no factory stand or power train for it if it's been sitting under a bench. IIRC, there's some wrenches for the Atlas that fit the various adjustments that are special, if those are missing you'd have to make some replacements. The bull wheel needs to be checked for missing teeth, as well as wear or rust on the various sliding members. There's a lot of flip-cap oil cups, too. Does it still have the special vise? If that's missing, that's an expensive item. Does it have the special shaper toolholders? A regular Armstrong-type lathe toolholder will work, but it's not the right tool for the job. All up, with all the parts, vise, factory stand and powertrain, I've seen the Atlas go for $600 at a very active school auction with rabid bidders. Probably actual value is somewhat less. With missing parts, no vise, just the bare mechanism, maybe $200 or less.
Really it depends on the type of work you want to do. They are powerful metal working machines.
Consider the half round items - how do you turn that on a lathe or do it clean by hand in production... A shaper. In stroking action takes strips of metal off and is actuated to the next location and strokes again...
Thanks to everyone for the explanations. Especially Larry G, for pointing me at the short video. That made all the explanations make sense.
There were also pictures of a 7" Atlas lathe at the same site. Comparing the pics of the restored one, to the one under the bench,it looks like all or most of the bits and pieces are there, including the original vise.
It's too bad I don't have the time or the money. After looking at so many fine examples of restored machinery, it looks like it would be an interesting project.
The vast majority of appropriate common jobs can be done about equally well on either machine (mill or shaper). Some jobs are far better performed on one than other, and a few can only be done on one or the other.
People tend to use what they either HAVE, or are most familiar with.
I have two mills and one shaper and all get used a good deal, but the vertical mill probably gets used the most (not surprising).
I use my shaper for squaring up blocks, and for planing the abrasive scale off steel and cast iron billets (the tools are easy to resharpen). I also use it for dovetailing (like for lathe quick-change toolholders).
Unlike my mill, my shaper has power feed, so I can put it to work and not have to stand there and crank the thing all afternoon. It's also 'dirt cheap' to operate ... no expensive cutters to buy.
The wording will give you a biased result. Needs to be more neuter.
My opinion? There's millions of "conspiracies" around. Most of them are a bit like the male Chihuahua sniffing at the female Great Dane in heat. The rest are going head to head with each other.
Lots of stuff has been taught by belief systems. The earth is flat, the sun circles the earth, the moon is a sacred fish egg, the stars are painted on the dome of Heaven, disease and mental breakdowns are caused by demons/sin/curses, tossing a virgin in a volcano gives it constipation, crops will fail if you don't sacrifice the Year King, shooting stars and comets are omens of the will of the gods, working iron requires the blessings of the secret gods, etc. Even statistical analysis contradicts some belief systems. Once we remove everything that contradicts one religion or another, there isn't really all that much left.
Oh, and the lefties really hate the present version of Darwinian evolution as it suggests a biological basis of social behavior. They'd rather believe in the inheritability of acquired traits, that would allow changing human nature by converting everyone to their belief system. That's uh, Lysinski?
When does public school become a church of beliefs? Where do you draw the line? Science is a belief system with lots of magical powers. That could pass as skills. But we are tearing the school metal shops down. Political correctness adapts a person for cleaning the toilets of Hillary's abortion clinic.