The questions your asking cannot be answered with a simple "yes" or "no". What may be suitable for some, may be totally unsatisfactory for others. Allot depends on the specific application, or, as most people need/want "widest possible ranges of multiple applications". The design of the machine plays a huge part also. If your making a pick-and-place machine, for example, your requirements would not be as critical as say, for example, a hobby router capable of cutting wood, plastic, aluminum, steel, 3d embossing, and all the while keeping an acceptable level of tolerances. Nobody here is telling you "it won't work", as it very well may work perfectly for your application. Were just here to help people avoid potential mistakes we have already made. Yes, I have a pile of stuff that never made it on my machine. I admit it. Anybody that claims they haven't made bad purchases...is a liar.
Now, I'm definitely not the expert on your questions, by any stretch of the imagination. But I will try. I'm not even going to state that I am correct in my own assumptions.
why this motor would not give me my 665 oz-in or close to it when using a 56vdc power supply
Max rpm on this machine is going to be 180-200 rpm
The same could be asked at the race track. My car has 450 HP and 500 foot pounds of torque. However, at 200 mph, the torque would drop off drastically. I need some nitrous oxide (more voltage) for a boost over a wider range of speed. These figures are made at optimum conditions, and not at an industry standard. You should be able to find spec sheets on your motors. If they say 665 oz at 200 rpm's, then there ya go. I have seen spec sheets where the torque drops like a cliff face at 5 revs per second. Take advertised specs with a grain of salt.
?should this work yes or no.
Dunno. (that was easy to answer!)
?the other motor e33 sigmax 996oz-in 4.5vdc 8.4amps
same max rpm 180-200.
will these work with a 56vdc 800 watt power supply
yes or no.
If I were a betting man, this is where I would put my money!! Lets see....800/56=14.3 amps. Depending on the quality of your power supply (again, no industry standards for determining the actual performance. Power supply makers have a
BAAAAD reputation for stretching the truth.) it should put out 14.3 amps. It
should do the trick. Don't forget to add up the amps from the other motors for a total. If it's a cheap unit, it might not even hold up to 8 or 10 amps at 56 volts. Or it might for 15 seconds. Or it might hold up forever. If your using 3 motors, 14 amps might be on the slim side. When power supplies burn out, they can be potentially dangerous. Even a computer P/S can burn out, taking the house/occupants with it in a worst case scenario. We should think about that when we add that extra hard drive or upgrade to that power hungry graphics card. Power supplies are very important. Many times a problem outside can be traced back to the P/S. That's why lots of people build there own. They can rest assured with a high confidence level there power needs are being supplied correctly.
? what should I expect to see when powered up an I make a first move.
hopefully, movement. (ahhhh, another easy one)