Classic stepper motor buzz WITH A TWIST

So, like many of you, I was inspired by how simple a finished 3d printer looks and figured, hey I could build that in a day!...oh was I wrong

My issue now is with my RAMPS 1.4 and stepper motors, everything is mounted and ready to go but I wanted to run the test code to double check everything works after all the fun I had with my power supply (multiple electrocutions), and of course, it doesn't.

My steppers (NEMA 17) are making the common buzzing noise and sporadically changing directions BUT I've noticed that if I apply a load to them (i.e. squeeze my fingers on the shaft) it will behave!

Even stranger still is that the direction I apply this torque on the shaft will dictate which direction the shaft will spin (it will always spin opposite to said torque).


I don't really believe in the supernatural but as this is my first serious electronics project it's making me wonder more and more each day....

please if someone's smart enough to find a logical solution it'd be MUCH appreciated, but until then I'll keep screaming skywards to the gods of electronics to stop making my life miserable

any suggestions are welcome as I'm pretty stuck, thanks

I had this problem several months back, and if I remember correctly (which is iffy at best), to fix it I had to change the voltage coming from the pololu stepper driver.

Edited 1 time(s). Last edit at 08/09/2014 09:38PM by 3D-ME.

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What you are seeing is a case of stepper motor resonance. The magnetic forces in a stepper make it act like a mass-spring system and mass spring systems will have a resonant frequency. If you step a motor at it's resonant frequency, at each step, the rotor will actually start vibrating back & forth about the nominal step position so extremely that it loses its position altogether. When you apply a load with your fingers, you are changing the resonant frequency, and you are also adding damping to help kill the resonance.

For the most part, when you get your motors assembled into your machine, the resonant frequencies become pretty low - below most normal step rates. Also, microstepping increases the stepping frequency so you are rarely have to worry about resonances.

Thank you both for the quick replies,

LoboCNC, you're saying that once I have the whole machine assembled there should be enough damping to fix this?

My worry is that my machine is mostly assembled. I'm waiting on a heated bad from ebay but thats about it, so I'm worried that that might not quite do it.

For example, I've finished building my extruder (mounted right on the x-axis carriage) and that motor is acting like all the others, even though it's turning a fairly large brass gear (6" diameter) and the only extra load would be the filament itself.

Do you have any creative ideas as to fixing this? perhaps adding some material, maybe rubber washers between the motors and mounting plates or something else to dampen the vibrations?

Oh, and I've tried all the micro stepping possibilities with no luck

have you verified the wiring. aa bb -a-a -b-b, if not then you could need to swap the end two wires.
sounds like a wiring issue to me.

If your motors are already connected to your screws and belts, then I'm probably with jamesdanielv - you may have a wiring problem.

You can also try turning the current up or down on your drivers as this will affect the resonant frequency - - if it is a resonance problem.

Listen to both of these gentlemen. First, the easy thing to do is adjust the screw on your stepper driver board just a little. If that does not change anything, then try swapping the 3rd and 4th wires. If you have one set of poles reversed, it basically makes the motor just oscillate in place (buzz). Except if you apply enough force to skip over to the next pair of poles, and then the momentum then keeps that going. Kind of like a magnetic hot-potato.

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"Never argue with stupid people, they will drag you down to their level and then beat you with experience."

I just went through and double checked all my stepper wiring (I'm using 6 lead NEMA 17s, but I found the proper common wires to ignore) and tested the motor with every polarity combination on the coils with no success but similar results each time.

I have tried many different current settings in all of these arrangements too.

The motor bounces around and shivers but seems to be making a net rotation in one direction, then switches direction (like the test code is telling it to) and sometimes it will make a half rotation smoothly before going back to its old ways.

I've also noticed that every time I turn my power supply off after a test the motor makes one smooth half rotation before turning off completely. Could this be some sort of clue? could it be a voltage issue since I'm using four leads to power the 6 lead motor?

Thank you all again for the help.

can you give the motor serial id to us to research? also do you have other stepper drivers to try?

quick question what power source are you using?

I also have 6 lead motors, but only 4 wires. I don't have the second and fifth pins wired to my motors, they are insulated and isolated from everything else. I had this problem (among countless others,) on my own printer before, so I'll do some brain-racking to see if I can remember how I fixed it!
It might be possible that the firmware could be the issue, however, I'm not sure how realistic that idea may be... I'm pretty sure it has to do with the wiring.

Edited 3 time(s). Last edit at 08/11/2014 12:02PM by 3D-ME.

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Quote
James G-J
I just went through and double checked all my stepper wiring (I'm using 6 lead NEMA 17s, but I found the proper common wires to ignore) and tested the motor with every polarity combination on the coils with no success but similar results each time.

I have tried many different current settings in all of these arrangements too.

The motor bounces around and shivers but seems to be making a net rotation in one direction, then switches direction (like the test code is telling it to) and sometimes it will make a half rotation smoothly before going back to its old ways.

I've also noticed that every time I turn my power supply off after a test the motor makes one smooth half rotation before turning off completely. Could this be some sort of clue? could it be a voltage issue since I'm using four leads to power the 6 lead motor?

Thank you all again for the help.

OK. Good first steps. But as jamesdanielv suggested, we could use the motor model number and PSU at this point. It sounds like you have the 6 lead figured out. If it was 5 lead, then your problem would be simple (get new steppers, you cannot use 5 lead). Now, the commons, you have them floating correct? You dont have them tied together or to ground? Also, you may want to tell us the brand of stepper drivers on your RAMPs. Then we can figure out what voltage reading you should be seeing on your drivers. The big clue here is the behavior when shutting off your PSU.

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"Never argue with stupid people, they will drag you down to their level and then beat you with experience."

I just want to quickly say first that I'm blown away by the amount of support this forum has given me and personal thanks to the four of you who have been a god send, without you i'd have a lot less hair to say the least haha


The steppers were a cheap lot of 5 off ebay, only info on them is as follows:

TYPE 103H5208-1242
4K1-1096 02
1.6 ohm 1.8 deg/step
LOT NO. 10702F
SANYO DENKI made in indonesia

My power supply is from the back of an old desktop tower, it's a Power Man FSP300-60BTV
with a DC output of, +3.3V-28.0A , +5V-30A , +12V-15A, Max output 300W

Like 3D-ME, I have the second and fifth pinouts unpowered as those are my commons, but they are neither tied together or to ground as the only info I found said to leave them insulated and disconnected from everything.

Would you recommend that I install the proper firmware and try sending commands through proterface or something similar instead of my test code? My only prior issue with that was getting the software to run without all my endstops and thermistors hooked up (though I have all that hardware now). My scare is that I had a similar problem when testing my steppers before I built my machine but it seemed to fix itself and the test code would work as it should.

Unfortunately I do not know the brand of my stepper drivers, or my entire ramps board as it was also purchased cheaply off ebay, and though they look like the standard pololu's I'd doubt if they are the real deal.

Okay, I was able to recreate your problem on my own printer by moving then 4 pin motor socket on my ramps over by 1 pin, so that only 3 of the 4 motor wires were connected. So that makes me suspect a wiring issue.
Double-checking the wiring to the Ramps may be a good idea at this point, and I would install Sprinter and test it over pronterface, but the new firmware may not be really necessary. Have you tried homing the axis, and if so what does it do?
I have a cheap Ramps board from ebay, too, and the (A9488) polous haven't given me too much trouble. (well, at least the two fried ones was my fault, not theirs!)

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James G-J
My power supply is from the back of an old desktop tower, it's a Power Man FSP300-60BTV
with a DC output of, +3.3V-28.0A , +5V-30A , +12V-15A, Max output 300W

While not related to your stepper issue, you will very likely have issues once you get your heated bed. It's a 300W power supply, but for what you'll be using, it's only 180 watts (12v * 15amps) if the manufacturer was honest in it's rating (probably not).

Typical heated beds will draw ~10amps, hot end typically 3-3.5 amps (40watt cartridge heater), and several amps for motors, electronics, etc. At best, you will be borderline and that might lead to a lot of fustration chasing down gremlins and phantom problems related to insufficient power available. If you can leave the heated bed off, you'll be able to commission your printer, but then that defeats the purpose of having a heated bed.

here is what i get for info on the motors. what concerns me is the voltage required to drive the motors .Voltage Rating: 6.4VDC (Unipolar Connection) / 9.0VDC Bipolar Connection


Specifications:

Series: Nema17
Type: Standart
Coil Type: 2-Phase Hybrid
Voltage Rating: 6.4VDC (Unipolar Connection) / 9.0VDC Bipolar Connection
Supply Voltage: Up to 12-36VDC
Rated Current: 1.2A (Unipolar Connection) / 1.0A (Bipolar Connection)
Resistance: 1.6Ω
Steps per Revolution: 200
Step Angle: 1.8°
Holding Torque: 60.2 oz/inch (418mN-m) Bipolar Connection
Rotor Interia: 0.31 oz/in² / 5.6g/cm²
Diameter - Body: Square 1.65" (42.00mm)
Lenght - Body: 1.540" (39.00mm)
Diameter - Shaft: 0.157" (4.00mm)
Length - Shaft: 0.630" (16.00mm)
Connection:


PIN1 -Red- A
PIN2 -Blue- B
PIN3 -Yellow- A-
PIN4 -Orange- B-
PIN5 -White- Common
PIN6 -Black- Common

So I've double and triple checked my wiring as well as trying the new wiring suggested by jamesdanielv with no luck still, the new wiring (leaving the fifth and sixth pins unattached) results in the motor locking up completely (regardless of the current adjustment) making the motor impossible to turn with a quiet humming....does anyone have any more ideas I can try out? because i/m completely out and this goes way beyond my knowledge of electronics.

GOOD NEWS! the motor is spinning and behaving somewhat like it should with the test code. YOU WERE ALL RIGHT, wiring issue, my fault. I went back to the basics and got my ohmmeter out again after trying all the possibilities but this time the readings made a lot more sense, since I'd been getting more and more familiar with the logic behind everything.

SO, the motor spins for a few rotations then spins back but it still stalls and hums sometimes and needs a bit of a boost to get it going again. I'm overjoyed so I'm not too concerned with that right now, though i know i'll have to deal with it sometime, just happy it's proving that it can work somehow.

I've tried reversing the polarization on one of the coils with a slight improvement but the stalling persists.

For anyone with similar issues try disconnecting the two outside wires from your six lead stepper motor (my two commons turned out to be pins 1 and 6)

Thank you for all the assistance and creative solutions you've all come up with to help me it was very much appreciated, feels so good to see it behaving like a motor for the first time

Hey again everyone,

So I have my printer fully assembled and wired and just finished sorting out my firmware and software, I'm running pronterface on my mac, and I'm running into a scarily similar problem again.

When I ask any of the axes to move a step they click and look like they may have moved but when I repeat it's clear there's no net rotation and the motor is slowly just shuddering in place.

When I ask them to move ten steps I get a quick high pitched whine with no movement, and when I try this with any of the micro stepping options this whine turns into a lower hum sound but still no movement.

I've tried adjusting all the pots on all the drivers with no luck as well as rewired one of my motors to flip the polarity of one of the coils but it behaves the same as the rest.

I also went back to the test code to double check and it works.

Any Ideas?

Have you tried to home it first?

I have and I get the same movement issue.

The motor just shudders around randomly and will sometimes start humming in place before catching itself.

I figured it might be an acceleration issue maybe asking the motor to change speed to fast and stalling it out but i've turned the acceleration waaayyy down and it doesn't seem to help.

I've also tried swapping the polarity of the one of the coils in one set of wires so I can do all these tests with both options but no luck.

http://cncsuperstore.com/index.php?route=product/product&product_id=63

Wow. You got some funky stepper motors.

Look half way down that page. Your pinout goes:

1 A+ (red)
2 B+ (blue)
3 A- (yellow)
4 B- (orange)
5 COM (white)
6 COM (black)

So, float your 5 and 6 (leave unconnected).

Match this to your RAMPS:

2B = orange
2A = yellow
1A = red
1B = blue

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"Never argue with stupid people, they will drag you down to their level and then beat you with experience."

It seems like your having the same issue I am... I uploaded a file and pressed print to see what would happen... everything moved to the (-) end and wouldn't stop so I shut off the power. I have posted my problem on here and it seeming like my end stops weren't configured right in the firmware. Maybe check out my post.

Thanks Hazer but my wiring is actually different to that, i have to float my 1st and 6th pinouts. I've got one of the motors to behave a little bit, i just had to spend hours tweaking the values for feed rate and acceleration to find my sweet spot and get the motor to spin and stop correctly. Though it seems like no one else has this issue with their motors (maybe every does so let me know) because my motors will only turn correctly with a feed rate of exactly 40 and acceleration of 300....so hopefully this will continue on to the next step in all of this and the motors will continue to behave once I hook everything back up and try running some g code through it

but then again, thats only to get a smooth rotation, it still won't make single steps correctly and sometimes seems to randomly pick a direction instead of showing consistency

whats the voltage on your powersupply?

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My power supply is from the back of an old desktop tower, it's a Power Man FSP300-60BTV
with a DC output of, +3.3V-28.0A , +5V-30A , +12V-15A, Max output 300W

and you're definitely using the 12v+ line ?

have you got a multimeter?

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yup I'm sure. All the electronics seem to be okay I'm thinking I might have got moody stepper motors. I hooked up my board to an oscilloscope too and all the wave forms look correct and are 12v.

Just a question to give me some direction here, has anyone else had to tune their firmware to their stepper motors to make them behave because mine are being very difficult and require very exact values and I;m worried once I get to the g code it won't be able to react to all the commands

I once had a problem with my steppers when I had a typo in the steps_per_mm setting, causing the setting to be different than what the motor can handle. What firmware do you have on your RAMPS?

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