no yeah youre totally right! Ultimately I did these tests because I had a feeling that the comments didn't really care about efficiency benefits or power density as much as "well it would have been EASIER to do steppers" -- and on that note, I wasn't entirely sure was true...

thank you for your support botFarm #8746! love to see it, we love robots

Well, I can't speak to every situation, but here's one way that can help: Consider running at max speed - the power supply is basically equivalent to back emf in this situation. Therefore the current through the windings is probably just enough to combat resistances in bearing, air, etc. This allows the motor to spin at this speed, but with nearly 0 current through the windings, and therefore nearly 0 torque. Ok now consider raising the voltage. Now, at that same speed we have the same back emf, but our power supply hasn't used up all it's available voltage yet. Therefore we have the ability to push some current through the windings, allowing us to actually use this speed under load (perhaps slinging the bed of a printer). Note that the current in this situation probably isn't hitting the driver chip's current limit! Therefore current through the windings could be the same as a lower speed and lower voltage system, but the effect is a higher speed in yours.

@EveryFlavorRobot ok so it's what I thought. It's allowing the motor to overcome the induction voltage..... like sliding the balance point farther up the speed scale. Side quest question then. What is the difference between current and voltage as far as the magnetic field is concerned. I'm asking about the field the windings create. Is the field stronger with higher amps, or higher volts if set at say 100w total power.

​@@JH-zo5gk Tricky question because it depends on what you are assuming. If you set wattage constant, and have a winding of copper floating in space - then apply a voltage to see a current determined by Ohms law. V = I*R. Most motors have very small resistances, usually low KV motors will have the largest winding resistances, but the most I've ever seen was 10 Ohms, and the least I've seen was 0.01 Ohms. This winding resistance will cause heat. This heat will cause meltage and is the limiting factor on your magnetic field. Now, If you put that winding in a DC motor, then you will find that the magnetic field will swell until the speed causes enough back emf causes it to shrink. OR still the windings heat up from Ohms law again and start to increase in resistance and eventually melt insulation to become one giga winding. NOW, If you add a circuit to limit the current such that the motors do not burn up due to Ohms law, then you will not see any difference in changing these things because you have already hit your maximum current. (that's why our max speed at torque was the same across voltages in this video) TLDR; Therefore, it is hard to answer your original question -- simply because voltage and current are linked! you cannot create a current without a voltage, and any limiting of the current is actually coming from a circuit that is switching on and off the electric field (voltage). I hope this helped! -- consider joining our discord where people love to discus things like this btw!

Very true, some day I will do a comparison of high end stepper motors because I am curious about them! I bet with thinner laminations and stronger magnets and smaller air gaps you can make some serious improvements! However that said, I WAS comparing them against bldc motors that I got from AliExpress for 3.99usd - so roughly the same price point as these (which I stole from an ender3)

Thank you!! (Love your channel btw)

@@EveryFlavorRobot Thanks!

Sorry about that, maybe we should do a video on understanding sound design because I do not get it 😭

Oh no 🤔🤔 maybe we will try out normal postings if a lot of people have this issue

Aw yeah you get it 🤠🤠🤠💪

@@EveryFlavorRobot it was honestly one of the best engineering related RU-vid videos I've watched in a while, you not only handled the criticism with grace, but came up on top after! respects!

@@skyslycer no you're on the right track. To give them the best possible chance, you would want to find the motors most efficient speed and gear the system such that you're using that speed. Ultimately we didn't go through the effort because we can see that the maximum power (assuming all was converted to perfect mechanical power output) was still not high enough to compete with our bldc motors. To do better we should use larger stepper motors, but at that point it becomes unsightly hahaha

@@xymaryai8283 there's tons of UFOs flying around unless you're one of those nerds who knows bird names

Stepper? I hardly even know her!

@@gizmoguyar good point, I could have summarized it better I think. For me I genuinely didn't have an intuition for what "high speed/ low speed", "high acceleration", or "small size" meant in quantitative terms so I just tested it out real quick. Then I thought it might be useful to show some maths for the upper bounds of motors in general. Thanks for the feedback, summary, and for watching!

Go for it! Sounds fun to me 👀

Ideally you would gear any motor down or up such that it's operating in its most efficient speed and torque. We didn't want to change the etch a sketch robot so we kept it at the reduction that was available to us 😅

@@zebedie2 our MotorGo board that runs the etch a sketch in this video is a custom BLDC controller that I made a few months ago! We are still developing it so that exact version isn't online yet, but everything we make is open source :))

@@thomaskletzl6493 so this is a bit I couldn't fit in the scope of the video - but there are two limits to the "maximum current/ maximum torque" 1) for stepper motors of this style and materials, you will reach something called flux saturation. Reportedly close to 2.5x the rated current of these style motors, though I haven't tested it. This is essentially when the increased current will not generate stronger magnetic fields at a useful rate. You also risk demagnetizing the magnets at this range. 2) as you mentioned the thermals are an issue, and with stronger cooling you definitely can push motors a bit past their "steady state". However, Nema 17 motors are traditionally closed off and your only cooling option is through the case. Ideally you could force convection through the windings themselves.

@@EveryFlavorRobot do you have infos on how much microsteps is usefull? My drivers could go to 256x currently im on 16x i have no idea what is usefull and what not

@@thomaskletzl6493 ok so this totally depends on what system performance you need, but let me try to give advice: Concern 1: noise - you will probably notice substantially quieter motors at 32 uSteps and probably won't notice much quieter past that. Concern 2: processor speed - if you need a max speed and have to set it with step and direction pins, keep in mind it will limit you if running on a slow microcontroller. At 256th uSteps that's 50k+ steps to command PER ROTATION so at high speeds that could get spicy for small microcontrollers without hardware timers Concern 3: accuracy, especially under load - stepper motors are designed to fall into "cogging" detents to ensure accuracy. Realistically as you increase uStepping you lose accuracy in exchange for resolution of electric field angle. What you will see is a lot of "magnetic backlash" as your motor will fail to move between uSteps. Because of this, I've never seen above 16 or 32 uSteps used correctly. BUT there are cases when you could find them useful. There are also stepper motors that are wound specifically for high res uStepping - these will perform differently because they are wound and designed to reduce cogging, which will reduce their powered off torque as a trade-off. Hope that helps! Good luck :)

What really is the problem with steppers though? Do you think if the commutation was just synchronised better and higher sample rate controllers did the switching at an appropriate timing, along with an adequately designed rotor/magnets and stator/coils would perform as good or better... Perhaps? Would adding another set of magnets and coils on the same axle, at an offset.. to compensate for the time the coils would have to be off. And evening out the duty cycle to occupy the entire spectrum make the torque more consistent? If so that's a pretty good idea ain't it?

Oh and I'm talking about axial flux, plus I'm thinking of using the entire stator worth of coils all at one, i.e commutating them. Then to smooth them out, just putting another set of stator and magnets on the same axle/stator/rotor. Just a small distance apart, slightly off a few degrees off phase. Such that 100% of the time.. a whole lot of copper would be used to turn the rotor? Would love to have a validation on this.

Stepper motors are overrated by hobbyists, and underrated by industrial engineers. That's the truth of it.

@@DUIofPhysics Not true. Typically experienced professionals tend to use horses for courses. However, industrial engineers do have a bias towards BLDCs (we call them PMSM). But that's because they do everything steppers can do but way better. In today's day and age, there is no reason to choose steppers except for high-volumes low-margin designs. In the past, we did not have the compute for closed loop commutation, so steppers were attractive.

@@TheaMakes interesting, perhaps we should clear up some misconceptions that we remember working through when learning those topics and maybe do some experiments to test some things we are still in the way to learning... I'm glad you liked our explanation of stepper motors!

@@LoganDark4357 did you know our bldc etch a sketch is a custom BLDC motor controller? Stay tuned, we will be releasing the design with our next video 🤠

@@samm7716 using stepper motors for closed loop is interesting! We did a little testing and didn't find a way to fit it in the scope of this video but we could do more in the future. Essentially however, this is a commutation improvement. Keep in mind that the max speed and torque will still follow Lorentz and Faraday's equations. Commutation can just help get closer to that! When we tested advanced commutation on steppers, like FOC. We discovered a few things: 1) you need extremely high precision encoders because the motors have effectively 100 pole pairs. This means that for each of those ~3.6° segments, you need enough data points to calculate the best field angle to drive. Only during those points calculated will you get improved performance. 2) you need extremely fast clock cycle on the computer driving the controller. This is because of how many field updates you need to send, unless you have a hardware generated sine wave. Our max speed was limited by our calculations which was disappointing and didn't do it justice. 3) the gains in efficiency aren't nearly as cool as in a low pole pairs motor, especially when considering micro stepping. This is because micro stepping is already approximating a sine wave quite well 4) most unfortunately, FOC commutation like SVM can sometimes make more use of the voltage range for a motor but not for stepper motors. This is because the phases are 90° out of phase and thus are already maximally using the voltage range. Tldr; we tried and it was disappointing and gave up, but may try again in the future!?!?

please do, I really liked the style and content of this video, and it felt like the topic of closed loop servos explained in this style would be a great video to watch, atleast for someone like, no one talks about, how bldc and steppers are kinda similar in this regard

Yes dude and you're so real for that

Thanks Wren!! Making this video taught me so much about them too 🤠

I'm so glad you found it useful!! I personally loved making this video

Williams Krater Charlotte Stevenson Benstein

And don't even get me started on the sketch sketches and the etch etches

@@EveryFlavorRobot They're all really sketchy tbh. Even a bit etchy

Motors are one of the topics that has confused me quite a bit coming out of FRC (where we are limited to like 5 motors) so more content would be nice. Also motor controllers would be good.

@@disastermaster7898 👍

thanks! I had a little fun in photoshop with it ahaha

Hahaha fair enough, back at this point I was missing some understanding on how RU-vid works - this video was more of a dev log on an ongoing project than a standalone video, so the pacing and information is sparse and weird. Thanks for the feedback tho! Noted