Author Topic: Power supply for Nema 23 Stepper ?  (Read 2001 times)

Offline mc

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Re: Power supply for Nema 23 Stepper ?
« Reply #50 on: December 05, 2018, 05:16:17 AM »


THANKS VERY MUCH FOR THIS ....BUT WHAT DOES IT MEAN TO SOMEONE THAT DOESNT SPEAK A WORD OF ELECTRONICENGLISH !

or just layman terms. You will have to forgive me...looking at that reminded me of so many lessons at school where I couldn't understand what the hell the teacher was talking about ! But i do appreciate the effort you made to find out the details so thank you again.
In layman's terms, you can ignore it. John just likes to reverse engineer these kind of things, and post the info for reference.

All you really need to know is how to wire things up, which is why I'll try to only post the basic information needed to get things working, as it can be too easy to confuse people with information that's not needed.

And I apologise for taking you the wrong direction with the enable circuit. I keep forgetting lots of stepper drives default to enabled, as everything I've done lately requires an enable to work.

Offline Will_D

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Re: Power supply for Nema 23 Stepper ?
« Reply #51 on: December 07, 2018, 04:40:08 AM »
With regards to the photo in post #12:

Are the Blue and Yellow ferules crimped onto the wire or are they solder or are they just slipped on and then the connector screw does the crimping. I am just about to do about 50 or 60 of these joints!
Engineer and Chemist to the NHC.ie
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Offline mc

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Re: Power supply for Nema 23 Stepper ?
« Reply #52 on: December 07, 2018, 06:06:06 AM »
With regards to the photo in post #12:

Are the Blue and Yellow ferules crimped onto the wire or are they solder or are they just slipped on and then the connector screw does the crimping. I am just about to do about 50 or 60 of these joints!

They're bootlace ferrules/cord end terminals depending on where you are.
You get proper crimping pliers that crimp them square, but you can just nip them up with some side cutters, then rely on the terminal to crimp them, however that often results in them flattened too much so you struggle to get them into terminals.
A set of crimping pliers isn't that expensive (just checked and they're about 13 on eBay just now), and they make using bootlaces far easier.

Offline John Swift

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Re: Power supply for Nema 23 Stepper ?
« Reply #53 on: December 07, 2018, 04:54:23 PM »
Hi Buell

 In the absence of instructions for the pulse generator board

I have continued with the iterative process working out the details of the pulse generator details

Now I think I have corrected my problems connecting to the NET

here are two versions of the connections between the stepper driver and pulse generator board
 using either the pulse generator  common +5V or common 0V

while the diagrams don't show all the details of the board

they show enough to predict the state of the enable switch for the motor to run
and explain why the voltage across the stepper driver input terminals  are closer to 4V instead of 5V due to the 100 ohm resistors on the pulse generator board
(thats if you measured the voltage across the pulse generator terminals before and after you connect them to the stepper driver inputs)


    John

Offline Will_D

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Re: Power supply for Nema 23 Stepper ?
« Reply #54 on: December 08, 2018, 07:00:27 AM »
They're bootlace ferrules/cord end terminals depending on where you are.
You get proper crimping pliers that crimp them square, but you can just nip them up with some side cutters, then rely on the terminal to crimp them, however that often results in them flattened too much so you struggle to get them into terminals.
A set of crimping pliers isn't that expensive (just checked and they're about 13 on eBay just now), and they make using bootlaces far easier.
Thats just the info I need, Many thanks MC
Engineer and Chemist to the NHC.ie
http://www.nationalhomebrewclub.ie/forum/

Offline Johnny Bravo

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Re: Power supply for Nema 23 Stepper ?
« Reply #55 on: December 30, 2018, 09:01:44 AM »
This is a very interesting thread,with evidently some very experienced people responding. I don't want to hijack this thread,but I think my questions would be relevant. There seems to be a myriad of considerations when choosing stepper motors and drives. Unfortunately,for the newbie,some of these considerations are very difficult to quantify.  So here is what I want to do....

I have a couple of Longs motors Nema 23 steppers, 425oz with an inductance of 6.8mH per phase.
Drivers can handle up to 50v.
Psu is 36v 9.6A
Ballscrews have a 5mm pitch.
Now, lf I use that formula used earlier in the thread,these motors "should" be fed about 80v... More than the drivers can handle. However....
I want to use it with a laser welder. My feed rate will be dictated by the frequency at which I can fire the laser,in my case, 40 times a minute. Assuming a maximum spot diameter of 2 mm and 50% step over,this would give me a maximum feed rate of 40mm a minute. Obviously it's not like a lathe or a milling machine where the load goes up exponentially with regards to the depth of cut. The load will be constant. So.... I would still need to rapid occasionally, but it's not really a major issue.  So, what would the best route to go be? Should I uprate the psu to 48v? Would I be better off say using a 3 to 1 reduction on the stepper motors? That would lend itself to a more compact set up, and more controllablility with finer work with say a 0,3mm spot weld and 50% step over.

Enlighten me !

Offline philf

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Re: Power supply for Nema 23 Stepper ?
« Reply #56 on: December 30, 2018, 01:12:12 PM »
Johnny,

A 5mm pitch ballscrew directly driven from a half-stepping 200 ppr motor would give you a step of 0.0125mm. Is this not fine enough resolution for your welding job? A 1:3 reduction would obviously improve the resolution but if you don't need it why add it.

40mm/ minute is pretty pedestrian even by stepper standards. I'm sure your 36v supply will be more than OK at the low speeds (8 rpm) you're talking about with a decent margin for rapid moves.

Phil.
Phil Fern
Location: Marple, Cheshire

Offline Johnny Bravo

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Re: Power supply for Nema 23 Stepper ?
« Reply #57 on: December 30, 2018, 02:12:12 PM »
Thanks Phil
If I had to add the extra 3-1 reduction,I could tuck the stepper motors in between the linear rails and make the whole set up more compact. The reason I asked, was, with such pedestrian feed rates, as you correctly point out, would it not be better to use the reduction and use full steps instead of micro stepping? Surely these stepper motors have a sweet spot where they run really nicely? I know with the servo motors on my cnc lathe,they are definitely happier not running at really low rpm. Surely here must be a certain rpm where they deliver maximum torque?

Offline philf

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Re: Power supply for Nema 23 Stepper ?
« Reply #58 on: December 30, 2018, 03:49:04 PM »
Hi Johnny,

Running a stepper in full stepping mode can cause resonance problems. Half stepping or particularly microstepping helps to get around the problems.

On my CNC mill I use Nema 23 4N-m motors in 1/8 microstepping mode with no problems.

Phil.
Phil Fern
Location: Marple, Cheshire

Offline Johnny Bravo

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Re: Power supply for Nema 23 Stepper ?
« Reply #59 on: December 30, 2018, 04:05:42 PM »
Having messed around with one of the stepper motors already, I have noticed 1/2 steps seemed smoother than full steps. Still think I will run the 3-1 toothed belt reduction, as it makes for a tidier install. Jury still out on running 48v psu or possibly swopping out Chinese stepper drivers for Geckodrives and running 80v. I have a nice toroidal transformer that would give me 80v dc with the necessary gubbins...

Offline mc

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Re: Power supply for Nema 23 Stepper ?
« Reply #60 on: December 30, 2018, 06:25:08 PM »
At those speeds, I doubt you'd notice much difference with a higher voltage power supply. The only real benefit of a higher voltage would be during rapids, especially if you wanted high accelerations.

As Phil has mentioned microstepping does give smoother operation. Obviously there are limitations, but generally 8 is a good compromise between smoothness and needing high pulse rates. There are not really any benefits from using a higher microstep setting.

It's worth noting that microstepping does not really improve accuracy. While microstepping, the driver is essentially balancing the motor shaft between two magnets with varying levels of pushing/pulling. Stiction and forces in the system will also affect the position, so the position can only be guaranteed to within one step.


I'd say run with the 36VDC supply and see how you get on.
Given you're in the UK, I certainly wouldn't pay the extra for Gecko drives. Even cheaper Leadshine DM drives (or some of their copies) give as good performance. If you want the best performance possible, Leadshine EM drives are far more advanced than Gecko drives, and much cheaper! (EM806 retail is 106, and the G203V is 148 )

Offline Johnny Bravo

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Re: Power supply for Nema 23 Stepper ?
« Reply #61 on: December 31, 2018, 06:11:19 AM »
Thanks for that.
Only reason I mentioned Geckodrives is I know where there are a couple I could have for little to no money... :ddb: