Problem with cranking up the current for steppers
Hi all
I have this setup
PoKeys57CNC
3 * NEMA 23 - 0.7Nm - 1/4" shaft (1=Z, 2=Y)
NEMA 23 - 1.3Nm - 1/4" shaft (X)
Power Supply - 24V 10A (Noname)
Stepper Driver 2.5A - PoStep25-32
My problem is when I crank the current up for the Y-axis. RIght now my settings is 1Amp for X-axis, 0,5A for each stepper on the Y-axis and 0,5A for the Z-axis. I would like to run the two steppers on the Y-axis with more current, because I have understood that this will give them more torque, and right now (with only 0,5A each) they do not have power enough to run to the bottom of the Y-axis, it is like my dragchain is simple too heavy for it to drag it (hope it makes sense?).
The stepper drivers I am using have a jumper to switch current for the steppers (0,5; 1; 1,5; 2; 2,5), when I just try to increase each Y-axis motor to 1A, a relay shots in when trying to power on the setup, and it wont start.
Does anybody have suggestions for some troubleshooting I can do, or have anybody tried similar things?
Thank you.
(hope this is the right place to post, else please let me know)
Re: Problem with cranking up the current for steppers
What size is your machine?
Re: Problem with cranking up the current for steppers
What are the current ratings of the motors? If you exceed the ratings, you'll damage the motors.
Where is this relay connected?
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
wmgeorge
What size is your machine?
The size is 1000m * 750mm
Quote:
Originally Posted by
ger21
What are the current ratings of the motors? If you exceed the ratings, you'll damage the motors.
Where is this relay connected?
Up to 2A for the three small motors and up to 2.8A for the large motor
I have not connected any relays to the setup, I think it must be the PSU? But I really don't know. It can also be that it is not a relay, but it just act like one. When I power up the setup, it sounds like a click and the setup shots down. The LED on BOB is only on for half a second or less.
Re: Problem with cranking up the current for steppers
I am guessing your “no name” power supply is not up to the load and it’s shutting down. Is there a voltage rating on the motors?
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
wmgeorge
I am guessing your “no name” power supply is not up to the load and it’s shutting down. Is there a voltage rating on the motors?
Ok so I should try to switch PSU to maybe a 36V? This is what info I have about the motors
https://ibb.co/7CycQ6r
1 Attachment(s)
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
tangi
Ok so I should try to switch PSU to maybe a 36V? This is what info I have about the motors
https://ibb.co/7CycQ6r
I guess I am not smart enough to figure the voltage out but if your limiting the amps I don't see how it could damage the motors using a 36 volts. But you need to look at the amp rating of the PS and get one designed for CNC work. It may be a DC power supply but your stepper drivers are outputting pulses. Here is a screen shot of a stepper motor being operated at different voltages. FYI.
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
wmgeorge
I guess I am not smart enough to figure the voltage out but if your limiting the amps I don't see how it could damage the motors using a 36 volts. But you need to look at the amp rating of the PS and get one designed for CNC work. It may be a DC power supply but your stepper drivers are outputting pulses. Here is a screen shot of a stepper motor being operated at different voltages. FYI.
Thank you very much for the chart wmgeorge. I am not smart enough neither to figure it out. The Y-axis is set to a very low velocity in Mach3 to have some torque and is running as I remember 1/8 steps. I tried back and forth, and this was the best results as I could get. But sadly I cannot use, I think 1/3 of the possible machine area of the CNC, because the Y-axis isn't strong enough to run to the bottom of the axis.
Re: Problem with cranking up the current for steppers
I have been searching a bit more. I thought that maybe my wiring could have something to do with it. My drivers are wired in parallel and not serial, can this maybe have an effect that causes the problem? It seems that a lot of people are wiring the power in serial mode between the stepper drivers.
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
wmgeorge
I guess I am not smart enough to figure the voltage out but if your limiting the amps I don't see how it could damage the motors using a 36 volts. But you need to look at the amp rating of the PS and get one designed for CNC work. It may be a DC power supply but your stepper drivers are outputting pulses. Here is a screen shot of a stepper motor being operated at different voltages. FYI.
36v shouldn't damage the steppers, but it can certainly damage the drivers. Looks like the PoStep25-32 are only rated for up to 30v.
Re: Problem with cranking up the current for steppers
Yes, it does say on the driver printboard max 40V, but yeah in the manual 30V. But I am thinking of changing the PSU to 36V, but then turn it down to maybe around 28V. Does that sound as a good idea?
Re: Problem with cranking up the current for steppers
Your drivers are undersized re voltage for NEMA23
24 volts is not enough for good performance. I've been there and done that.
Somewhere on Gecko's site I read 2 things:
1. If you double the voltage you quadruple the torque
2. The total amperage draw of your steppers can safely exceed your power supply output by 40%
I drive my NEMA 23's with a 48 Volt power supply with drivers that are good for 50 volts.
With 4 x 2.5 amp steppers, you will be fine with a 7 amp 48v power supply.
You will never get satisfactory performance at 24 volts. Bite the bullet and upgrade and you will be amazed at what the difference you will get from your machine.
Re: Problem with cranking up the current for steppers
Hi Tangi - This seems to point at a wiring problem. No matter what the current setting is or the voltage, when the system is turned on the motors should lock if wired correctly. Going from 24V to 28V will not change things significantly. You do need to find out why the system is faulting before you do anything. Often 24V is not enough to overcome the motors back EMF when they go fast. The highest voltage the controller can take 30V is best if your game seems 40V is OK. But first check that everything is wired correctly. At low speeds if the motor is getting its correct current then that means the motor is providing its full torque. if you have a switch in the wrong place this can create a surge that trips the controllers. Check the wiring diagram and ensure all switches are where they should be. Plus you can put a limiting resistor into circuit to limit the amperage. This should be explained in the manual/wiring diagram. You can disconnect a motor at a time and turn the system on to see if this isolates which circuit is at fault. A 10A supply should be heaps for this system. Check your set velocities or accelerations are not ridiculous (bring them way down while you are sorting this) as if they are trying to take off like a rocket that will trip the system, sometimes you can be a factor of 10 out somewhere and this is all it takes...
If your axis is working somewhere along it then it doesn't work somewhere else this maybe mechanical alignment. Should move the same everywhere along an axis. Do not daisy chain the drives ie do not use in series or parallel. Each drive should be supplied via an individual wire otherwise you will get different voltages across each driver... Cheers Peter
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
rodw
Your drivers are undersized re voltage for NEMA23
24 volts is not enough for good performance. I've been there and done that.
Somewhere on Gecko's site I read 2 things:
1. If you double the voltage you quadruple the torque
2. The total amperage draw of your steppers can safely exceed your power supply output by 40%
I drive my NEMA 23's with a 48 Volt power supply with drivers that are good for 50 volts.
With 4 x 2.5 amp steppers, you will be fine with a 7 amp 48v power supply.
You will never get satisfactory performance at 24 volts. Bite the bullet and upgrade and you will be amazed at what the difference you will get from your machine.
Okay thanks for the reply rodw, it seems that I must upgrade my drivers, to get full performance then.
I been looking around. Would something like this be good for a setup like mine?
https://www.omc-stepperonline.com/st...er/dm542s.html
Or this, but it's a little bit more expensive
https://www.omc-stepperonline.com/st...42t-m542t.html
Or can you recommend any?
Quote:
Originally Posted by
peteeng
Hi Tangi - This seems to point at a wiring problem. No matter what the current setting is or the voltage, when the system is turned on the motors should lock if wired correctly. Going from 24V to 28V will not change things significantly. You do need to find out why the system is faulting before you do anything. Often 24V is not enough to overcome the motors back EMF when they go fast. The highest voltage the controller can take 30V is best if your game seems 40V is OK. But first check that everything is wired correctly. At low speeds if the motor is getting its correct current then that means the motor is providing its full torque. if you have a switch in the wrong place this can create a surge that trips the controllers. Check the wiring diagram and ensure all switches are where they should be. Plus you can put a limiting resistor into circuit to limit the amperage. This should be explained in the manual/wiring diagram. You can disconnect a motor at a time and turn the system on to see if this isolates which circuit is at fault. A 10A supply should be heaps for this system. Check your set velocities or accelerations are not ridiculous (bring them way down while you are sorting this) as if they are trying to take off like a rocket that will trip the system, sometimes you can be a factor of 10 out somewhere and this is all it takes...
If your axis is working somewhere along it then it doesn't work somewhere else this maybe mechanical alignment. Should move the same everywhere along an axis. Do not daisy chain the drives ie do not use in series or parallel. Each drive should be supplied via an individual wire otherwise you will get different voltages across each driver... Cheers Peter
Hi and thanks for your reply too. The motors are seperately connected to the PSU and is not looped, if that is what you mean? I have been playing a lot around with the velocity and accelerations. The Y-axis moves really slow and accelerates really slow (do not have the numbers here unfortunately), and still it can't move to the bottom of the y-axis without missing steps. I haven't tried disconnecting motors, to like trying to isolate the problem, so that's one more thing I can try out, next time I have time to play around with it. Thanks again.
Re: Problem with cranking up the current for steppers
I have bought from Stepper on line and they give good service and I did get a power supply replaced under warranty after I returned it to a local Aussie address.
I think you are on the right track. I use Longs Motor DM542A controllers and are very happy with them. A friend also has them on a Syill CNC mill based on a Seig SX3 mill and he does good work. Look for the Elephant on ebay. I bought these a few years ago and I know the A was significant at the time
stepper motor driver-DM542A - China Changzhou Longs Motor
FOr the few extra dollars
Re: Problem with cranking up the current for steppers
Quote:
Originally Posted by
rodw
I have bought from Stepper on line and they give good service and I did get a power supply replaced under warranty after I returned it to a local Aussie address.
I think you are on the right track. I use Longs Motor DM542A controllers and are very happy with them. A friend also has them on a Syill CNC mill based on a Seig SX3 mill and he does good work. Look for the Elephant on ebay. I bought these a few years ago and I know the A was significant at the time
stepper motor driver-DM542A - China Changzhou Longs Motor
FOr the few extra dollars
Okay cool, and thanks for a fast reply. If ebay it has to be an european one, I live in Europe and I see that stepper online ships from within europe, so it shouldn't be a problem with them :)
Re: Problem with cranking up the current for steppers
YEEEES! It worked, it is working so nicely now! Thank you all for your inputs. The setup is now as follow:
PoKeys57CNC
3 * NEMA 23 - 0.7Nm - 1/4" shaft (1=Z, 2=Y)
NEMA 23 - 1.3Nm - 1/4" shaft (X)
Power Supply - 24V 10A (Noname)
Power Supply - 36V 10A (Noname)
4 * DM542A,4.2A, 18-50VDC
And it sounds better and runs smoother and faster. The 36V psu is powering the four motors and the 24V psu is now only powering the PoKeys57CNC, but I think I will add some proximity swithches to the setup and power them with the 24V psu too. Thank you all again! :)
