Is it normal that my boss "uses" me?

You can view this as your boss entrusting you with more and more responsibilities because they appreciate your work and maybe are putting you on the fast track to a management position. You could stick it out and sooner or later confront the boss for more money, promotion, etc.

If that fails, go over the bosses head and bring up your concerns. Don't expect success, but you could bring light to their laziness.

If you're gonna quit anyway, you could always refuse the assignments given on the basis that you're improperly trained on the equipment in question and that you fear for your safety, the safety of the other employees around you and the integrity of the equipment.

Honestly, in any industrial setting if I were to bring up honest safety concerns and they fell on deaf ears with management, I'd immediately tell them to jam it up their ass sideways and walk out the door. That's no place to work.

If you're feeling sleazy, you could always mis-operate equipment so as to sabotage it. When the boss hit the roof you shrug and claim improper training and management.

Dude this is the best position ever. Let them get lazy. Let them have you do all the work. That, my friend, is called job security. Work your ass off. Eventually it will get noticed by someone higher.

Well, if you just started working there, it's not realistic to expect to get a promotion to supervisor, so forget about the other guys that did.

Having these responsibilities could be an opportunity to move up in the future though. Just make sure your boss is actually noticing the job that you're doing. If this is going on for any long period of time and the boss is still treating you like garbage even though you're doing so much, then it's probably time to think about leaving.

At that point you could threaten to leave if you don't get a raise and test whether or not they actually see the value in what you're doing.

Hang in there. I used to be like your boss that is trying to get you trained to work many jobs. I had an expression, "You beat the fastest horse", meaning the people that are good, we count on to do their best on any job we put them on. What an opportunity for you. Not only are you increasing your skills, but you have got to feel better about your abilities to do most any job you are put on. This alone is invaluable for any challenge you have in the future.
You have a bright future. Do your best and you will be rewarded in the future.

Sounds to me that you are an unskilled laborer so I'd be really happy to have a job in this economy and not bitch and moan because you feel a bit put upon.
It also sounds to me that this guy is trying to get you to quit, so I wouldn't confront him at all, if you want to keep the job, that is.

Here is what you need to do:

Start screwing up and causing minor accidents. Wait for your boss to have a talk with you then improve instantly for about a month then repeat the process by going back to screwing up until the next talk.

After a while your manager will get used to closely supervising you and only give you the jobs in which he can look in on you fast which tend to be the easiest office jobs. Being in such close contact sets you up for promotion and special treatment.

I've seen this process work many times and it is really the key to promotion. You can't be dependable or they will rely on you too much to promote you. Just a little too competent to fire but too unreliable to stay at the bottom. That is the key to success in big business.

I wouldn't wish unemployment on anyone.

As your new to the job this isn't unheard of. What ever you decide to do proceed with caution.

Basically you are an expendable worker who has to take a constant pounding in the ass from your boss's metaphorical dick, all the while smiling and getting a shit wage for it.

Where there's a mill there's a way

You're the company bitch. Or, as once stated in King of the Hill, the Golden Goose. This probably won't change. If you start slacking, they'll get on your ass. If you keep going, you'll wear yourself out. Not only should you quit, but you shouldn't work as hard on your next job. You should always do just enough so your following the rules, plus a little bit more when the company actually needs it. This way you'll look competent and reliable without all of the responsibility. As for getting promoted, just get friendly with the right people and appear all around nice.
Seems to work in most cases, anyway.