I use my Marcato Atlas 150 for fettuccini and occasionally to make lasagna noodles. One side if the fettuccini head has a spaghetti roller. I've used it a only a couple of times because the pasta is so thin it appears to be angel hair or capellini rather than spaghetti. Am I wrong in my assessment?
No, you are not wrong. The roller you describe produces a noodle that is closer to capellini than spaghetti.
when you roll out the pasta to make the sheets, keep them pretty thick... 3 or 4 out of 6. then you'll get thicker spaghetti. if you roll out the sheets very thin, you'll get angel hair of fideo. but... when they dry, they can be really brittle so cook them while still pliable and of course, only for a minute.