Have I got a 17 or a 23 stepper motor

[pavingmaster]

Hi there folks,Only registered a couple of days ago and have a problem working out what stepper motor Ive got. Had to return a new cnc machine as it was incomplete and the replacement has shorter stepper motors than the first machine.Im supposed to have Nima 23 stepper motors. The motors on the origional machine were 56mm wide and 53mm long, (the windings section less the two ends) . The motors on the replacement machine are also 56mm wide but are only 32mm long and the dealer says that length makes no difference and that the shorter motors have the same values as the longer ones.No markings on the first machine but the sticker on the second machine gives the motors as Long Stepper Motor. Model 23HS6620B, 2.8A(U), 1.8deg/step, no:20110720. Sent an email to Longs Stepper Motor CO in China but got no reply. Can anybody help me out here please?

[LUCKY13]

That measuremnt sounds right for nema 23 motors. You can do a google search and find the exact measuremnt of each size motor. The mounting flange is what they go by for frame size ( Nema23 - Nema 17 and so on are different frame size, mounting flages). The lenth will effect the power. All though all motors are not equal. You can have a shorter motor same frame size that has more power than a longer motor. But normally if they are same series motors the longer, the more power. If they run the machine it really doesnt matter. And sometimes smaller motors do just work better depending on the setup of the machine and motor design.



Jess

[LUCKY13]

Here you go I found a pretty good link

NEMA Motor Dimensions



Jess

[pavingmaster]

Hi Jess, Thank you very much for all that information.I referred to that link you posted and the dimensions match up with a 23 motor. So am I correct in now taking it that the nos 17, 23 etc only refer to dimensions for the purpose of fitting and replacing motors and that there is some other numbers,letters or whatever to indicate the power of the motor and that one can have Nima 23 motors with different power ratings. The motors in question have no markings apart from a little sticker on the shorter one. They are probably all imitations from China.If you know of a link where I can find the power of my motors I would be much obliged.Martin.

[RomanLini]

The "size23" refers to the mounting size, ie motor diamter, holes spacing and shaft size. All the stuff needed for swapping motors onto a machine.

In size 23 there are a few "frame lengths" also called "stack sizes" and these determine how long the motor is (obviously) but mainly how long the rotor is and how many magnets the roto can hold. All that adds up to motor torque, and likewise electrically the longer frame motors can have higher magnetic fields and more heat dissipated by the coils.

So to sum that up; in size 23, there are different lengths, and the longer the motor the higher the torque and power of the motor.

If you check out a stepper manufacturer site that lists lots of size23 steppers, you can see they all have similar torque based on the motor length.

Assuming your motors are the square frame type, check this page;
23HS Stepper Motor 57mm 1.8degree, MotionKing Stepper Motor
the 41mm long motors are around 55 Ncm (78 oz in)
the 51mm long motors are about 90 Ncm (127 oz in)
the 56mm long motors are about 110 Ncm (156 oz in)

The part numbers on that page are very similar to the ones you quoted.
Hope that helps!

[LUCKY13]

As RomanLini all ready stated you are correct.


And normally the longer the motor the more power. Getting this balance of power and speed is the trick to steppers. To big a stepper will not have the speed ( RPM) and to small a stepper will nnot have the torque.



So as long as they run the machine good it really doesnt mater there size, its there performance that matters.


Steppers are funny anyway to me. Wiring hookup and driver will have a hugh effect on there performance along with the size of the stepper. There are a few ways to wire them, plus many different types of drivers. Depending on what drivers are used if better performance is needed its possible to get drivers to help with this as long as the motors where sized right to begin with.

ANyway it soounds like you have alearned a bit about what you have, and what is possible. Next time you will be have more understanding of what your getting into.


Let us know how the machine works out.


Jess

[pavingmaster]

What Im wondering now is will the drivers that I recieved with the longer motors and still have, be correct for the shorter motors? What do you guys think about that one.
Martin.

[James Newton]

techref.massmind.org/techref/io/stepper/nemasizes.htm much better page showing all the dimensions for NEMA motors with a table and drawing.

[pavingmaster]

Thanks for that , very clear. Where could I find the values of 23 stepper motors of varying lengths. Martin.

[RomanLini]

I already posted the link in post #5, your part number appears to be from that same manufacturer and the page I linked has a heap of steppers you can compare your motors with.

[pavingmaster]

Thank you for all the help lads and the time taken to help me out here. Bought the machine new on ebay from Markendice so must go ahead now and get it working. Will let you know how it works out. Martin.