Introduction to Stepper Motors for 3D Printing - The Basics you probably need to know - Episode 1
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- เผยแพร่เมื่อ 11 พ.ค. 2024
- Part 2 is here: • Let me explain microst...
Stepper motors! Pretty important for 3d printers, right? But does anyone understand how they work?
Me neither, but armed with a little knowledge and a lot of Wikipedia, and maybe some long nose pliers - we'll get to the bottom of this.
Join me on a 3 part voyage of discovery into what's inside them, what makes them tick (hah), how you drive them, and eventually we'll get on to how you shut them up!
Part one (this part) is about what they are, why they are, and taking them to bits and watching them move. Fascinating.
Any comments please let me know, I'm sure I've missed points, made mistakes on this one, corrections will go here or be picked up in the next episode.
Join us on Discord! There are many of us now! Hundreds! (okay, one hundreds but that's still a quantity of hundreds!) / discord
Waste: None. Nothing.
No steppers..okay maybe one stepper was harmed in the making of this video. For science.
www.lostintech.co.uk/waste/
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What about microste.....oh, ok
😛😂
what about backlash in the cheapo steppers?
I believe the cheap steppers are readily available and... dirt cheap because their intended application is driving the fins/blades on air-conditioning units. I imagine their backlash will be terrible as they don't have to be great for this purpose.
excellent explanation, those close up shots were great
More to come, most of the macro shots were of microstepping 👍😉
I was a bit surprised to learn a few things from this video. I thought that I knew a lot about motors since I used to repair AC and DC drives. TIL that I didn't know much at all about stepper motors and found the presentation interesting. Excellent job keeping it interesting and approachable.
Such a nice video, i was currently deep diving into the tech of my motors etc. so you helped me out a lot.
Somewhere in this series, can you mention that stepper motors almost never "break"? If it isn't working properly, it is almost always a broken wire, or sometimes a fried driver. I see all the time on reddit people said "my motor wasn't turning properly so I got a new one, but it still isn't working"
Eventually, the bearing in the motor is actually shot if you have it under too much lateral load. But you can just rebuild them.
Also it can sometimes very rarely happen that there's a latent defect in the terminal PCB assembly, so connections can break internally. Shouldn't really happen.
But normally yes you should always suspect the wiring first, it can be moving and breaking internally and garbage crimping quality is not out of the ordinary either.
@@SianaGearz Especially regarding their very slow speed compared to say a 2 pole AC motor spinning att 3000 rpm and those motors also last forever if their bearings are properly loaded and lubricated. So unless u tension the belts like crazy the bearings are unlikley to ever fail in these motors.
8:18 The printer knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or a deviation...
But if you don't know where you're not, your not going to not know where you aren't, so even if you subtract the difference from where you are not, to where you know you're not, then you only know were you are (not) if you knew where you are (not) before you knew were you are not now.
Hm. Rentaspoon said exactly the same thing.
That is incorrect. The driver counts pulses, but it has no idea if the stepper slipped or if it isn't told where it is at the start. A stepper motor is a relative motion.
You must have it find a stop switch to find the home position.
excellent explanation!
hello familiar face
Good info. Looking forward to more.
Looking forward to the next video. Great stuff, I'd like to hear your take on voltages to the steppers and why they are different for x,y,z and e. \o
Again, great vid.
Hey this is such a cool and entertaining video. I’m a student working on a stepper/laser project and algorithm gifted me this gem. Excited for next vid!
A stepper and laser project sounds really interesting 👍
Yes! Magic ✨
youtube recommended me this video, and i must say that you are great
Thanks, and welcome 👍
It would be a bit more accurate to say the printer has an unreasonable level of confidence that it knows where the print head is regardless of reality. There is no feedback in the act of driving the motor so, if something prevents the motor from stepping, you'll get a layer shift.
Great explanation of how they work.
I installed a lot of stepper motor assemblies back in the early '80's. This technology replaced magnetic particle clutches in highspeed impact printers. Impact printers were replaced by laser printers. The stepper motors were for paper feed. The iron powder in the particle clutches would not always demagnetize, for some reason, and the clutch would seize.
A motor with brushes will self destruct if it spins too fast. Robert Bosch dealt with this by having two shoes on a shaft that went through the rotor shaft. The faster the rotor spun the greater the centrifugal force on the shoes against cylindrical case which in turn limited the RPM's of the starter motor. Cf, the Bosch logo.
Another way is to have a switch in series with the brush circuitry. Centrifugal force will cause the switch to open. This is how a Teletype motor RPM is regulated on board ship where power is unreliable. Calibration was originally done by looking through a slit on a piece of sheet metal welded to a tuning fork at a dot on the motors fan. Later the tuning fork was replaced by a Strobotac from General Radio.
damn dude, this is an extremely good video!
Thanks!
Hi, if I use M82 command to use the absolute mode for the extruder, how the E number relates to the steps or the rotation angle of the stepper motor? I'm thinking mod the extruder motor to let it drive a rotary stage. Thank you!
After watching this video I knew I had to use the sub button.
Unrelated -new lifehack! my all metal hotend got badly jammed and I was too lazy to strip it so I turned off the heatsink cooling fan for 2 minutes which softened the filiment in the heatbreak(via heat creep) enough for me to push it through with a piece of wire
Yeah that's definitely a good time saver! 👍
Trinamic druvers can do a dual sensorless endstop detection🤔
i'm curious why the NEMA has 4 cables while the cheap has 5?
Ah, I didn't want to go into that, but the answer isn't too complicated, the cheaper one is unipolar, it has a middle wire between the coils (it's 6 wires internally, but middle is ground), so it doesn't reverse the voltage, it just switches one side to the other. I could cover it in episode 2 if enough people ask :)
@@LostInTech3D i second that
@@muffty1337 The NEMA has 2 separate coils. Each coil is wired separately, it can be powered normally or in reverse.
The cheapie has each coil wound twice, wound in opposite direction. So one coil powered gives the opposite magnetism of powering the other coil.
Now one side of all those coils goes to a separate wire, the common.
Which means that 4 transistor can step this thing. No H-bridges needed.
@@LostInTech3D Fun fact: these tiny cheep ones have a tiny pcb under the blue hood on the side. There you can scratch away one of the traces and then use it as a four wire stepper.
You are Genius
haha thanks
I'm doing a project basically to run a floor wiper that is connected to a motor, so the movement of the motor would just to forward-reverse for like 7 times. Am I doing it right by choosing stepper motor over any other motor like servo or even an AC motor ?
Good question, I don't know, but it probably also depends on your budget!
Hello. Nice Easter egg. Still watching the video...
2:52 "the spinning speed [of brushed motors] reaches a natural equilibrium of voltage vs friction i guess" - it's a bit more interesting and determined. With no friction, the motor spins up to the speed where the voltage it generates equals the supplied voltage. If there is friction, it will slow down, that is mostly because the effective voltage reaching the coils is reduced because now some of it is lost to the resistance of the windings, because now there is current. This is an oversimplification of course, but by compensating that voltage drop, the speed of brushed motors can be fairly accurately controlled. This is how it's done in most cheap audio-cassette decks.
Brushless motors can have magnets on the outside or inside. Just depends on what’s the rotor and what’s the stator typically.
For example brushless drill motors typically the rotor and permanent magnets are in the middle and the stator and coils surround it. More torque less speed is typically the trade off I think but I could be wrong in that last part.
I think you're right, the torque is higher, not sure about the speed either.
I should get a square wave from my driver then?
I have one that seems to grind, but doesn't. I can push it either way under power.
not necessarily a square wave, no, that part is coming!
seems to grind but doesnt? what do you mean? Being able to push it under power isn't a good sign unless you're using a lever of some sort.
@@LostInTech3D It has this awful chatter at random times.
It shakes violently back and forth and makes an almost grinding like noise.
At 1st I thought it was stripping the belt, but no.
Seems like you need a new stepper, I'm sorry to say. There seem to be some dodgy ones out there at the moment.
@@charlesurrea1451 that sounds like a bad cable really or your driver going into reduced current emergency mode due to overheating.
now I wonder how does my Prusa know where it is since they do not have limit switches, X and Y just go to the end of their travels and tap against the stop. Is the board just reading the change in current load on the motor or something to know its stopped?
Next episode 😉 but yes you are correct.
As I understand it: Yes. It sets the motor to a low current, drives it until it hits one end of the axis, detects the change in load, and then does that a few more times to check.
"It's all in the nex stepisode"
brb editing subtitles 😂
woopi woop di doot stepper time
But what about micro stepping, etc? Whatever that means. Seriously though, you understand this way more than I do at least!
It's just more time spent on Wikipedia 😂👍
Nice explanation. Not so sure about your comment that the larger stepper motor controller is much more basic than the ones on a 3d printer board. They are certainly more powerful, but why do you think they are less sophisticated? As far as I know, they can do just the same thing as any single axis controller on a printer board, but driving a much bigger motor.
I took it apart, it was just a bunch of optoisolators and random other stuff, including the 555 timer. It is way less sophisticated than printer drivers, yes. Not least because it only throws out dirty square waves, so dirty in fact I didn't even show them on the scope. All will be revealed later though.
These box drivers are fully analog as far as i know- I think Even the cheapest basic allegro drivers are digital- have negitive feedback loops for monitoring and have thermal cutout and I think over current protection too
Yep I looked for a driver chip and either it was hiding, or absent! 🤣
@@LostInTech3D the stepper motor controller boxes are basically just the part that handles the high current to actually drives the motor, the control electronics is separate. Think of them as being analogous to an amplifier, which doesn’t generate the music but idrives the loud speakers.
@@LostInTech3D I think you were careless with the disassembly of the box driver and let the microhamster escape😜🤣🤣
Hmm, I guess it's the next episode for magic numbers? Or maybe the third one ;)
😒 maybe
For those wanting to disassemble your own stepper motor because you are curious; do NOT do it, unles it's a junk motor. The magnetism in the rotor will be drastically reduced when you pull it out of the stator.
Interesting! Well, anyway nobody should want to open theirs, now they've seen inside one.
That makes no sense, why would magnetism be reduced? You are just making this up arent you?
I thought that, so I googled it, and I did get some mixed results. The theory, I think, is that removing it pulls it against induced magnetic from the coils (ie why it's hard). This would be pulling it through a field. But as to whether there's any truth behind it, I have literally no idea.
I could test for it, I guess. Hold torque before/after. But that motor has no before and was already a bit dodgy.
It for sure does. I pulled a spare one apart and when I put it back together it was almost free spinning, I could just barely feel the steps. Very weird!
@@Makex_sweden I'm afraid not 😕
i kinda want to write my own marlin at that point :P
Haha, I mean it's not impossible...but it's beyond my skill level, especially getting everything to work at the same time in real time!
@@LostInTech3D I already changed a FAN pin on marlin, how hard could it be :P
I mean, the basis is very simple: move stepper x steps for each axis with information from gcode. The difficulty comes from supporting a lot of hardware configurations and fancy stuff like interpolation, pressure advance and other extra features.
while simultaneously PIDing the hotend and bed. It boggles my mind how an atmega can do all this.
@@LostInTech3D it is running at 16 MILLION operations per second, so I think a lot of people underestimate how many calculations these tiny things can do. Where they break down is when dealing with bigger numbers, e.g. an 8 bit chip calculating 32 bit floats will tank performance. But just adding, subtracting and multiplying is pretty zippy.
Am I the only one who was looking all over for episode 2 before realizing this was released a day ago? 😂
Haha you never know, I could have released them in star wars order
Hope you eventually cover vfa artifacts, it’s the only thing I have left quality wise that I cannot fix even with 0.9 steppers and info online is almost non existent/not helpful.
from what I gather, most people just seem to think they're resonance artifacts and changing print speed fixes them. I take it you've tried that though?
@@LostInTech3D yes a few times and also with acceleration. I don’t have much ringing but the vfa continue along the whole print evenly at around 2mm which makes me think it’s the belts but there’s 0 results when I try to search online with “2mm belt artifacts” and the few forums on vfa only mention steppers as the issue. Tried smooth and teethed pulleys and different belt tension to see if that helps but same result. Not an issue for functional parts but unless I print very low temp so the plastic is not glossy I can’t get quality objects without vfa. I will be trying klipper with input shaping when I get the time, maybe might help with vfa.
@@user-il8gt2ev9d I heard of extruder gears causing patterning. See th-cam.com/video/UWuSsYKI-YM/w-d-xo.html and th-cam.com/video/32dTLRNIYmw/w-d-xo.html
hop into discord if you want to bounce some ideas around, I imagine we won't have anything you don't already know but we have a lot of knowledgeable people in there.
@@user-il8gt2ev9d Do you have toothed or smooth idlers in contact with the belt teeth??
Smooth idlers would cause uneven curves when the belt teeth run over it, albeit I would consider this insignificant, it still _is_ something that might give very fine artifacts in the end.
Attached an encoder on the end and you get a servo
watch this space (assuming it arrives in time)
Which nerf blaster did you sacrifice for the 130 motor?
haha, I actually bought these off ebay! Not for this purpose though.
Part 2 when?
I have a TPU vid to do, and a pi screen vid to do, then part 2 👍 Hopefully < 2 weeks, if I actually put some work in 😂
@@LostInTech3D aah cool
555 timer!!🤣 what?they couldn't find a tiny hamster+ cammed hamster wheel to generate questionable clock/ timing pulses
Loved the content of this video but there is something wrong the for focus at many points in the video, I am not smart enough to know what it is but sometimes i found it uncomfortable to watch.
I guess it's the narrow depth of field with the macro lens, a trade off, if you want to be super close, you have a real hard time getting everything in focus and keeping everything in focus.
Anyone else find the Easter egg?
That didn't take long did it, I'll have to hide them better in future :) (or....are there more?)
@@LostInTech3D I did notice it as well!
Huge thanks for the extra effort! I'm really dependent on subtitles since English is not my native language and I've hearing aids...
0b1111001 is the only hint I'll give
what? 😂
you are welcome, I always make sure subtitles are on the vids and will carry on doing so! 👍
The stepper motor knows where it is at all times. It knows this because it know where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is, whichever is greater, it obtains a difference, or deviation
wow
That is incorrect. The driver counts pulses, but it has no idea if the stepper slipped or if it isn't told where it is at the start. A stepper motor is a relative motion.
You must have it find a stop switch to find the home position.
It's a copypasta, it's something from a video about a missile 😉
@@LostInTech3D Oh. Well, it is wrong, but getting upvotes.
I think most people recognise it as a meme, I'm not too worried