Which resolution setting best for my stepper?

[alexccmeister]

Hi,

I have a set of nema23 497oz.in stepper motors and Keling 5056 drivers. What microstep resolution setting will be best for this motor? I am currently set at 8 microstep. That is 1600 microstep/rev.

When to use low microstep resolution and when to use high?

Thanks

[H500]

The main advantage of microstepping is smoothness at low speeds. Eight is probably as high as you need since your motor probably cannot resolve any finer.

[alexccmeister]

Hi H500,

Thanks for your response. I am still confused with your last statement. Does the setting of resolution dependent on which motor I am using? Which motor can be used if I want to set up to microstep of 128? Which is 25600 microsteps/rev. Or do we really need to go this high? For me 1600 seems high enough resolution. Thanks.

[DennisCNC]

It's not really a matter of the motor but the cnc controller, most hobby pc controllers will put out under 40K steps per second. So if you are at 25600 microsteps/rev then you will not be going fast.

[kiwichris]

H500's comment about the motor not resolving the fine steps is more of a general statement about stepper motors, rather than your specific motors...

For what it's worth, my understanding is that anything above 10 microsteps (2000 per rev) gets you no advantage in positioning or smoothness on most stepper motors.

If you're set to 8 and it's working fine, I'd say stick with that...

[alexccmeister]

Wow! 40K steps seems alot compared to my Keling drivers. But I doubt I need such a high resolution. What kind of work require such a high resolution?

So what is the relationship between resolution and speed? High Resolution = Low speed and vice versa?

When would you use high resolution? And when to use low resolution? Thanks.

[alexccmeister]

Hi Kiwi,

Thanks for the update. So basically I don't need anything higher than 10 microstep. Thats good news. But I am still curious, when would I need to use the higher resolution though? If the setting is there, it must be for soemthing. Sorry if this question is a noobie's question. Thanks.

[kiwichris]

Hi-ho,

The only really high resolution stepper application I've seen first hand where the actual resoution was used was in a blood testing machine where a bunch of steppers directly drove a small pumps that pumped alternate samples and cleaning fluids in very accurate amounts though the innards of the machine.

The stepper motors used were very different from the ones we use in our machines, about 3 inches in diameter, and probably only an inch long. I assume that the large diameter vs length gave it more distance between poles, so the microstepping would be more effective, I'm guessing. I was servicing the printer attached to the machine, and got a look inside it while one of the lab techs was replacing something, he said they were 1024 microsteps.... (In a hospital pathology dept.)

You can still get high speed with microstepped steppers at silly resolution, but you need much faster step pulse sources than a PC can deliver. Mach3 does 45Khz, which if you're using say 256 microsteps, you'd only ever get a max speed of 52rpm, which isn't much good for much in CNC terms..

A reasonable speed of say 500rpm at 256 mircosteps, you'd need a pulse rate of 2.56Mhz... Which is just silly, but might probably not be unheard of in the world of expensive industrial steppers, although I've never seen one...

There are also some down sides to high resolution microstepping at high speeds, as it becomes less effective, and reduces torque. Hence some drivers 'transition' from micro to full stepping at some point around 5-10 revs/second.