Have I got the maths right?

[Robin Hewitt]

So I'm looking at this web page with NEMA 34 stepper torque graphs...

At 2000Hz it does 3.5 Ncm on a half step = 5 ounce inches? Sounds like it would make a good lettuce leaf turner in a restaurant :confused:

So that's 31.4 radians/second times .035Nm = 1.1 Watts

With 330 Watts input that's 0.33% efficient, or is my maths up the clack? :confused:

Did they mean 3.5 Nm? That would make it 33% efficient which seems a bit too good to be true.

Starting to think I'm the only stepper motor shopper in the entire world who won't buy a pig in a poke.

[Robin Hewitt]

I can't see the webpage you're referencing


I didn't actually point to the page because graphs seem to be secret and I don't want them to remove it. I've now printed out the bit I wanted, page 26, so here it is...

http://www.motioncontrolproducts.com/c2/uploads/HybridStepperMotors.pdf

2:1 down on 2.5mm screws means you need 8 rps out of the motor to get a lowly 1 cm/s on the G00.

If you wanted 1" per second do you still have the torque to avoid lost steps?
Pig in a poke without the graph, but I think I am stuck with the "suck it and see" approach because the information simply isn't there :beer:

[Gary]

Its a mistake, this has come up many times.
It will be 3.5Nm.
What motor are you reffering to?
It is unlikely they will remove the link, i dont think there is anyone there who knows how :)




I didn't actually point to the page because graphs seem to be secret and I don't want them to remove it. I've now printed out the bit I wanted, page 26, so here it is...

http://www.motioncontrolproducts.com/c2/uploads/HybridStepperMotors.pdf

2:1 down on 2.5mm screws means you need 8 rps out of the motor to get a lowly 1 cm/s on the G00.

If you wanted 1" per second do you still have the torque to avoid lost steps?
Pig in a poke without the graph, but I think I am stuck with the "suck it and see" approach because the information simply isn't there :beer:

[Gary]

Also those curves are very old and were done with drivers that are not available and at quite high voltages, so i would not advise you to use the curves as a firm axample of the performance you will get.
What torque do you need and what speed?

[Robin Hewitt]

What torque do you need and what speed?

1.3558Nm at 762 rpm would be nice, especially if I could do it at 40 volts :beer:

[Gary]

The SY60 is border line with 70V, and the nuxt motor up from that is the ST85STH65-2808.
I have attached the datasheet, but to get this torque curve that is on the datasheet you will need higher voltage.
The problem is that with the larger motors, you need the volts to get the speed.



1.3558Nm at 762 rpm would be nice, especially if I could do it at 40 volts :beer:

[Robin Hewitt]

Hi Gary
That was jolly good of you sending that :beer:
I am quite happy to upgrade all the stepper drivers and power suppplies to higher voltage, but I want to start with the 40 volts because it is already fitted and working.

Next one up in the Changzhou Fulling range is the 80mm length, largest I can fit, have you got a pdf for that one? Do I want to wait?

Much ta

Robin

[Gary]

The longer the motor, the more indusctance it will have, and will requre more volts to get it going.
Also the 80mm long motors are not in stock and will not be for at least 8 weeks, this is at MCP and also Zapp.

I am not in the office at the moment, but will get you the datasheet later today, but this image may help you :)

www.slidesandballscrews.com/pdf/sy85 torque curve.jpg



Hi Gary
That was jolly good of you sending that :beer:
I am quite happy to upgrade all the stepper drivers and power suppplies to higher voltage, but I want to start with the 40 volts because it is already fitted and working.

Next one up in the Changzhou Fulling range is the 80mm length, largest I can fit, have you got a pdf for that one? Do I want to wait?

Much ta

Robin

[Lee Roberts]

:o

You dont want that:
www.slidesandballscrews.com/pdf/sy85 (http://www.slidesandballscrews.com/pdf/sy85) torque curve.jpg

:cool:

You want this: http://www.slidesandballscrews.com/pdf/sy85%20torque%20curve.jpg

:beer:

[Robin Hewitt]

You dont want that: :cool: You want this::beer:

Unfortunately the X axes for the 80mm motor are gibberish ;)

On the 550 coil it goes 200 800 2000 4000 6000 pps

On the 420 coil it goes from 0 to 30 pps :rolleyes: