gary wrote:Harry, I have addressed this before but you mustn't have got the reply, but the NEMA rating is to do with the physical size of the motor not it's holding torque. For instance a NEMA 17 has a diameter of 1.7" if round or has a side length of 1.7" if square shaped.
Gary i understand but what i am confused about is i have seen NEMA 17 saying its rated 80 oz ! and others lowwer so they are all over the place its not like your buying this size and you get this power out of them...i'd rather stuff the size and they say we are selling a 50 oz Torque stepper motor .
Now obviously the larger the casing the more copper you can get in it so the more powerful motors are the larger sizes.
Wonder why there is a jump from the 17 to 23 size .....it also sounds like if they are telling the truth about their motors power rating the wire size is varying depending on who made them ?
But, my steppers are NEMA 23 but are only 35oz-in so you can't assume the larger the motor the more powerful.
This is what i have to be careful about as i don't understand why they sell them in a size and you think they are more powerful sounds a bit of a rort !
doing a quick google on 17s and oz i get a few come up nema 17 62oz nearlly twice your 23s ?
Having said that if you want 200 oz-in (generally recommended for your size machine) you would need to go to NEMA 23.
So what ever i buy i better make sure i look into that mother OZ as it could be anything from the sounds of it .
Floppy disk drive motors are NEMA 14 I think with very very low holding torque.
That sounds pretty low then it never had to work hard in those floppy drives
Yes if you are using a recycled motor and it doesn't have the holding torque written on it the only way (if it doesn't have a model no you can look up - many do) is to measure it the way you mention - there are some tuts on how to do that on the net. Persoannly I think it would be just as easy to hook them up and see how they go - if they don't have enough grunt then you need to source other motors.
This looked like a good test
http://www3.telus.net/schmaus2/elcts/mtest.htmlBut your more than likely right just to hook it up to what ever and see .
But if you buy new motors the holding torque is always specified.
I wanted to talk about this as i just didn't under stand why size and torque
are different in the same sized motors i would not have known there could be such a difference i have to check it out if price and oz is a factor or its pot luck you'd think higher torque higher price i will study this !