"DeusEx"

[mocha]

Thanks guys!

I'm just reading about the 540's and doing a side by side with the Kinco 2M880N (that was top of my list...)

I don't know what "microstep to full step morphing" is, or if there is any advantage of "256 microsteps", my reading list just got a bit longer!
:-)

[Jonathan]

I don't know what "microstep to full step morphing" is, or if there is any advantage of "256 microsteps", my reading list just got a bit longer!
:-)

The morphing thing is, from memory, switching to full step mode when the motor is run at higher speed. It's a good plan as you get a bit less torque when microstepping...
I wonder if the gecko's use vector current control, like the 2M880N, bet they don't...could be wrong.

To me it's obvious - get the 2m880N as that's about 50% higher voltage than the gecko which should have a much greater affect than the rest of it.

No point in using 256 microsteps ... that high wont help with accuracy (only cheating yourself if you think the resolution is 256th of full step resolution). As long as the driver does up to about 10 microsteps that's fine.

More info on microstepping here, here and here:

http://www.micromo.com/microstepping...realities.aspx
http://www.euclidres.com/apps/steppe...r/stepper.html
http://reviews.ebay.com/Microsteppin...00000002352664

Disclaimer :
Other websites are available ...
Your blood pressure can go down as well as up if you choose to read them ...

[JAZZCNC]

I wonder if the gecko's use vector current control, like the 2M880N, bet they don't...could be wrong.

If by vector control you mean current recirculation while stood still then yes they do.

To me it's obvious - get the 2m880N as that's about 50% higher voltage than the gecko which should have a much greater affect than the rest of it.

Only really apply's if your motors are good for the extra voltage.? Most nema 23's are not when wired parallel.!! . . . . Over rating a motors voltage will give extra speed but it also creates extra heat, iron loses etc which then slowly damages the motor shortening strength and life.

[Jonathan]

If by vector control you mean current recirculation while stood still then yes they do.

No, I mean vector control. I wont try and explain as it's a tricky one:

http://en.wikipedia.org/wiki/Vector_control_(motor)

http://www.eng-tips.com/faqs.cfm?fid=1062

Only really apply's if your motors are good for the extra voltage.? Most nema 23's are not when wired parallel.!! . . . . Over rating a motors voltage will give extra speed but it also creates extra heat, iron loses etc which then slowly damages the motor shortening strength and life.

Mocha is using the same motors as I am, or at least very similar - 3Nm Nema 23 with low inductance. I've been running mine on 75V since I got them well over a year ago with no ill effects. The highest temperature I have ever recorded was 60 celcius (so at least 25C below rated) on the case which was on a sunny day when the machine had been running for a couple of hours. Most of the time they linger around 45C. I check it regularly as I have an infra-red thermometer to hand and it's something to do whilst the machine's running...good for getting estimate of cutter temperature too.

[JAZZCNC]

No, I mean vector control. I wont try and explain as it's a tricky one:

No need to explain I know all about torque vecter drives but are you sure these drives mean the same.? I don't see any referance to torque vector control but I do see current limiting (Half current).?

Mocha is using the same motors as I am, or at least very similar - 3Nm Nema 23 with low inductance.

If these are the motors with 3mh inductance I've seen specs sheets flouting around for then your running them approx 20V over spec, this will sooner or later have an affect.!!

[Jonathan]

No need to explain I know all about torque vecter drives but are you sure these drives mean the same.? I don't see any referance to torque vector control but I do see current limiting (Half current).?

http://www.zappautomation.co.uk/prod...ec77476e499bf4

'The application of advanced vector control algorithm greatly reduces noise and vibration of the motors during operation, '

The link I gave in my previous post explains it better. In particular this is interesting:

'The motor operates in continuous mode rather than conventional stepping mode.The audible
noise and resonance effects associated with conventional stepping mode are effectively
eliminated.'

That sounds alike to the Gecko - although it's not full stepping at higher speeds it's applying a sine wave to each phase, so operating it like a 'normal' motor not stepper motor. Bound to be quieter and more efficient for obvious reasons.

I'm intending to implement vector control on the stepper driver I'm designing/prototyping.

If these are the motors with 3mh inductance I've seen specs sheets flouting around for then your running them approx 20V over spec, this will sooner or later have an affect.!!

Well it's been 16 months. I'll let you know if they break!
The formula you are probably using to say they are 20V over-spec (32*sqrt(L)) is almost certainly an oversimplification / guideline. I think the fact my real life experience with these motors shows the temperature is fine at 75V says it all.