[ryghar]

Hi,

I have a 6 wire stepper motor. The datasheet specified 1.6mH of phase inductance and 3A. This values are for full coil (middle tap unconnected) or half coil (start and middel taps connected, end tap unconnected)?

I will use these motors at 5000mm/min feed rate. Would you recomend half coil or full coil setup?

Thanks!

[ryghar]

Please, tell me if Iam wrong with this:

- According to the datasheet the motor has 4 phases and 1.6mH/phase. So, in full coil config, has 3.2mH
- The power supply, according to what I research, may have sqrt(3.2) x 32 = 57v. The driver mas voltage is 50v. I can use a 48v power supply with 3A x 4 motors x 2/3 = 8A.
- I plan to set microstepping to 1/8 in a belt driving system with GT2 and 20 tooth pulley. So, in a motor turn I will move 40mm and need 1600 pulses to do that.
My max cutting speed working with wood is 80mm/s. That are 3200pps. In a torque curve I dont see much difference in half coil setup and full coil at that speed. I will use maybe twice of that speed for G0 movements but i dont need torque in that. So, to cut at that speed full coil semms to be adecuate and to cut metals at slow speeds I will have more torque with full coil. I think that for me is the right choice.

Please, correct me if Iam wrong and any suggestion and recomendation will be appreciate.

Thanks!!

[joeavaerage]

Hi,
two basic rules for steppers:

The lower the inductance the better.
The higher the voltage the faster you can go.

Those motors have three wires on each coil (phase), one at each end and a center tap. DO NOT hook the center tap to either end, that results in an autotransformer
with a shorted secondary....bad. You will get the greatest torque by using the full coil, that is the two end taps and leaving the center tap isolated, it means the maximum
number of turns and therefore the strongest magnetic field for a given amount of current. It will also mean the highest inductance combination. Less than ideal but
it is what it is.

If you find that you start losing steps at speed then replace your motors with low inductance types. Low inductance motors have fewer turns in each coil an consequently
have to pass more current to maintain torque. Most buyers look at the holding torque when deciding on what to buy. You can make motors with high torque but only at
the expense of high inductance. Discerning buyers will see that a lower torque motor (low inductance) will outperform a high torque (high inductance) type.

The other trick is to use high voltage drivers like Leadshine AM882's, they withstand 80V

Craig

[ryghar]

Excelent, I think I got it.
I will try and see what happend. Anyway, here in Argentine you buy what you can, not what you want... (in this case i buyed without knowlege), worst scene.
Its my first build, learning it most important. For this build, maybe ends running slower, but its ok. Is for hobby, not for production.

Thank you Craig.

[109jb]

Does the datasheet you have list the phase resistance? If so, measure the 1/2 coil resistance and full coil resistance and compare to the datasheet. One or the other measured resistance should match the datasheet and will tell you if the datasheet values are for full or half coil.

[ryghar]

Yes it does!! very cleaver. I will check that!

Thanks!!

[109jb]

Also, 48V will be fine.