Electric Bike 4.0 - Pulley Failure

[@impuls60]

People learn a lot more from these fail videos than just watching you riding a finished bike. I certainly have :)

[@tin2001]

impuls60 Yep. Mistakes teach important lessons. You can be taught the right way to do things. But without seeing the wrong way fail, you never really learn why the right ways are right.

[@feha92]

In regards to mistakes, I enjoy that you include them. They tend to be the most interesting parts imo.

[@TheManShel]

I completely understand that you want to change your video upload schedule to maximize your workflow. However, I will say that I love to see these weekly updates, failures and all. The biggest thing I have gleamed from your work is that when something goes wrong, not to get frustrated, there is usually a good way to engineer around the issue. All in all, keep up the amazing work. I always look forward to watching your videos!

[@nicolasescobaravila7910]

TheManShel Yes! the attractive of the weekly videos has exactly been that, but I reckon that it would be significantly easier to edit just one long video than two short ones. So maybe he could do that, a long video not only to show a project working, but the issues he found on the way and how he solved them.

[@hamdan7210]

Yup right there with ya!

[@saifaddeenal-manaseer6325]

You'll go a long way in life if you have the mindset that there's always a solution, because there is. That's the point of being an engineer, solving problems. In fact this is true for many other disciplines, such as programming, research, and even machining.

[@USWaterRockets]

Is it possible that the modification you did shortening the motor with the lathe has messed up the balance of the motor?

[@TomStantonEngineering]

Yes I reckon that was the probable cause, so I'll have to re balance the motor and hope it solves it.

[@kiserleti4d4s]

maybe you can remove some mass from the pedal winch?

[@Robert-qm7yi]

Tom Stanton That doesn't make sense, unless what you cut off wasn't symmetric. If you trim the end of a rod it doesn't mess with the balance

[@buhatkj]

brushless motors are balanced after they are manufactured, even though they are generally symmetrical too, at high enough RPM i guess maybe just small variations in metal density matter. just like a car tire i'd think. hopefully he can use a RC brushless motor balancer and a little epoxy putty or some such to pretty easily re-balance it.

[@iwantitpaintedblack]

it might also be the clamping force of the lathe chuck squeezing the stator and the rotor together thus creating a grind,or knocking a neodiddlium magnet loose, it looks like the spoke that broke off, tore alonge its extrude/rolling direction, you can try some thermoplastics and bend them using heat, or a punch die cut continuous disk,

[@rens2998]

cant wait for you to hit one million, it feels far away, but its probably gonna be faster than you think

[@TomStantonEngineering]

Haha possibly one day! Thanks

[@rens2998]

Mikkelen haha well, in 2-3 years he'll probably be there

[@FusionFiber]

Sure it'll happen. This is some quality content you're putting out!

[@lescarneiro]

Man! Don't be sad! I think that the "failure" videos are the ones that teach the most! And you are very good in your crafting! I Being no mechanical engineer, I loved the Fusion360 part and your explanation on the case. For me, the showing of the steps is the most teaching and entertaining part of the projects, kinda like how the "one day builds" from Adam Savage (that are not built in one day quite often). So, congratulations on how far in the project you have reached so far, I loved the video! Keep up the good work you've being doing!

[@Enthropical_Thunder]

Yeah but as an engineer he could have just calculated the needed material, it is very basic. I would be very interested a video of him, demonstrating those calculations, so that people can solve problems without the need of a simulation program ;D.

[@Lasseu]

Mandernach Luca didn't he replicate it IRL with the weights? Fusion360 is free for anyone.

[@Enthropical_Thunder]

Lasse U I thought about actually showing how to calculate the needed material ( the needed radius for the whole, to withstand the pressure), with this formula everyone could calculate the needed material strenght without the use of any program or computer in general ;D.

[@Lasseu]

Mandernach Luca I would like to see it :)

[@rizalardiansyah4486]

That pulley analysis actually is very awesome! I'm a mechancial engineering student, and that calculation gives me an example of how and when calculations are used and how important they are in a design process. Thank you for including that!

[@Guysm1l3y]

I know it's frustrating but when you learn from failures like you show here that experience is priceless.

[@robertpearson2143]

Have to say I love the failure analysis. It’s great to watch your thought process. Your bikes are great and I have shown your Norway drone video to a lot of people because not many people know how fast and agile they can be and the scenery, video quality, and music are awesome. Your ability to get great 3D prints is also impressive. I don’t think I’ve seen much on how you get such good results. If you could add a suggested link to resources you found helpful or if you think it’s just the machine or filament. I have access to an Ultimaker 3 but have never gotten really great results on big parts and have tried numerous things to get big parts to print. The corners of the prints tend to pull up. I have tried a lot of different rafts, boarders, bed adhesives, and filament materials and brands. I wish you the very best and thank you for all that you do.

[@smad333]

Try increasing the Bed temperature and decreasing the Nozzle temperature to improve adhesion and reduce warping. On my CR-10s I am using 70 bed temp and 195 nozzle temp for PLA

[@robertpearson2143]

Adam Ladd Will definitely try it! Thanks!

[@smad333]

Oh and also another very important point is that new rolls print a lot better than old rolls that have absorbed moisture over time

[@Anonymouspock]

Robert Pearson What material? Also the Ultimaker uses a glass bed, which I've found with my similar bed, isn't perfectly conducive to sticking. Try some glue stick. Careful that it doesn't get permanently stuck in there though or else you might have to stick the whole bed and print in the freezer.

[@mbainrot]

with glass beds (having sworn by them prior to making the jump to PEI) there are four rules Assuming your running PLA 1) Clean enough to do surgery on - Go over it with IPA to remove fingerprints, etc then over it with soapy water (obsly being careful not to flood the printer), the soapy water will remove any residue the IPA can sometimes leave behind 2) Flat flat flat flat flat - For glass to work properly it must be very very level 3) You wanna **squish** the filament into the build platform, the way it works is it holds on via suction. Though if you move to PEI, ****do not**** do this, otherwise you will permanently bond whatever it is you're printing to the build platform and it's a nightmare to resurface thanks to the 3M adheasive :) 4) Slow and steady wins the race, fast and greedy gets pie in your face (sorry was in a ryming mood today lol) - You want your first layer to be decomposing food slow, like, 5mm/s slow, reason being is the first layer is the most important layer of the entire print. The absolute maximum speed that I can personally recommend (on point #1 clean PEI) is 15mm/s If you're using a plastic that shrinks a lot (ABS) or a bit (PETG) then you will want a higher air temperature around the print, atleast 25C though 40C is much better, particularly for the likes of ABS

[@anthonyrobertson1787]

You Doing a nice Job Tom, you may having a few problems, but your heading in the right direction 🖒

[@smad333]

Great video Tom, really enjoyed the spoke analysis

[@TomStantonEngineering]

Thanks Adam!

[@smad333]

I have been using a Turnigy CA120-70 150kV motor on a project, presumably the bigger brother to the one you have? It's very scary

[@MrWobling]

Me too - as a software engineer by trade, I dig the methodical approach.

[@benji376]

Love your high-quality videos, Tom!

[@elitedavidhorne8494]

The fails and how you deal with them are the best bit. Learnt a lot more from your fails than your triumphs.

[@thiagov6123]

As a mechanical engineering student, its awesome to see many things I study being applied to real world problems. Calculating the torque on the pully hub is a typical "Dynamics" problem, and verifying if it will resist or not the torque is a typical "solid mechanics" problem. Its literally something that I would have to do on a test.

[@BernardSandler]

I'm loving the iterative test/fail/succeed cycle. Learning so much about how you approach problems, diagnose issues, and resolve. Don't ever feel you need to do less of it!

[@jasonpan4]

this is rare stuff... to put all of your effort and don't hide your fails in the process in the video is remarkable and truly appreciated!! i have to sub now... cheers from Greece

[@TuckerJohnson7]

I really love seeing the design process, and your thoughts throughout the project

[@matt_metcalf]

I honestly like watching the failures and pit falls. That's really life and in a social media world where we just see polished, perfect products seeing the struggles is refreshing

[@joaoruibarrosmatos]

The project is awesome!! Please don't shorten the mistakes, those are the best parts of this videos.. that s how we all learn!!

[@smokin0137]

Please stay weekly, at least with updates. Thanks for the quality family entertainment.

[@jankarsch4935]

YEEES finally the full projektvideos are coming back. I Like the idea of getting surprised once in a while with a well thought through project. Thanks for changing it back :)

[@vincevht]

Hey Tom! Keep up the great work! You've inspired me to build my own electric bike. Based on the failure of your spokes, it looks like they failed with shear tear out. I’m not a huge fan of FEA analysis to predict those kind of failure modes so it’s something you can do with hand-calculations. I work as a stress/dynamics analyst and to predict those kind of failures, you can just do some basic hand-calculations and not rely on FEA. What you basically have here is a cantilever beam that creates a moment at your fixed end. You can calculate the force from the couple that is induced at the fixed end. You did a great job with a redesign to reduce the force at your bolt location and thus reducing your shear tear out stress. 1) You increased the vertical distance between the bolt and 2) you added more material from the center of your bolt to the edge of your part.

[@vincevht]

If something breaks and you have data, it's not a failure. It's science.

[@didu888able]

I like your videos! To see the entire design process including all the failures makes it much more sympathetic and relaxing to watch! I like the weekly video format! 👍😊

[@simr6493]

I love the way you can make sense of complicated problems and explain them to us noobs.... Keep up the good work!

[@davec200i]

Tom, would be happier to see the fails. They are interesting. Also no problem with the short videos, they are great to watch when I have a spare 10 minutes or so

[@coxsj]

Hey Man, mistakes are what engineering is all about. No mistakes, no learning!! Keep em coming, mistakes and all, they contribute to the overall interest! Thanks!!

[@VineethMuthanna]

You're doing great Tom ! Please take your time and do the best, we can wait. Can't wait!

[@benjaminervin3997]

Looking forward to your future videos! Watching you make mistakes and your analysis of them is the best part.

[@nicolasescobaravila7910]

I will tell you Tom that this failures, and how you solve them, are one of the best parts of your videos, you're a great explainer. I reckon it is easier to edit one long video every two or three weeks than a short one each week, so you could do that, maybe? a long video not only showing like a tutorial on the project, which is the best definition I can find, but an explanation on a couple issues that you consider you could offer some engineering insight.

[@jonnk7347]

I'm in my third year of mechanical engineering, and I absolutely love that you're making proper science out of shed projects! You should team up with Colin Furze

[@EdgePrecision]

I know you have already solved you spoke problem but consider this. What if the spokes came off the hub tangentially instead of perpendicular. Look at the way the wheel spokes are laced on bikes wheel hubs. If you slant them in the direction of the force it puts the load on both the fasteners the same way. I don't know how that would be for the regenerative breaking from the motor though.

[@oldrageface8706]

On the same note: look at how the spokes of disc brake discs are designed. Good idea! :D

[@RoelofH]

Great shots of you zipping past the trebuchet. I love the build so far. Stick to the double pulley. Take your time, you'll get there!

[@awo1fman]

It's fascinating watching this series and your analysis and approach as problems arise. It gives me a little more respect for the people who develop and manufacture products like this as well. I hope you are able to solve this vibration issue without to much trouble - it seems like it could be a showstopper.

[@williamwelmans3026]

An excellent video with real experimental engineering to boot. Hopefully you start a summer school workshop with all the engineering science behind ebikes!!.... I would certainly attend!

[@billrea4841]

Don't feel bad about the fails. The fails, and your clever solutions, are arguably the most important part of the process.

[@KURDinEXILE]

A single man full product evolution. Respect

[@mr2octavio]

You have a great way to run through the steps of the engineering input you do into your projects, keep it up!

[@schonnj]

Huzzah for the ups and downs of the creative process!

[@kustomweb]

I need a trebuchet in my backyard, you never know. Love this kid, a superstar for sure.

[@oskarkrogsgard3014]

I think the broken pulley part was really interesting to watch. Cheers mate! Keep it up :)

[@JohnDoe-rl9pp]

So far as the pulley goes, I'd say your #1 problem was thinking a safety factor of 2 was anywhere near enough. Heck, even Fusion 360 was giving you a big old warning about that.

[@sphericalsphere]

Today I learned that fixing the sidewall of the hole is a terrible approximation of a screw mount of the screw mount itself might be a failure point. Great stuff!!

[@arrowstheorem1881]

One of my favorite channel and KZbin. Keep on your good work!

[@vinnychoff]

Great to see you pick up on each issue and work on it to fix it. Look forward to the end result. I am interested in an eletric bike. Not sure about building one though. Great to see your build.

[@hamdan7210]

I'd rather see the weekly updates, regardless of fails or not. I like seeing how you're problem solving and moving forward.

[@AlvaroQF]

Typical problem when the bolt is not tighten enough, that’s why the constrains that you inserted firstly don’t match with reality. The second way to do it is much easier to be mounted. Loving this videos because you show the prototyping procedure, keep going on!!

[@carlandj]

Please keep the fails. The explanation of the torque calculation and FEA (Finite Element Analysis) simulation was incredibly insightful.

[@ianmontgomery2862]

I came back to this video for inspiration. Keep up the good work.

[@robinlovell1617]

Great series.

[@christopherpardell4418]

The pulley is not monolithic. That is, not cast nor milled out of a single material... it is an assembly, and the forces acting on its parts are therefore discrete, not shared. That is, the force of the motor is NOT distributed evenly thru all the spokes, because each is hinged and because the belt is somewhat elastic, it PULLS on the the top of the pulley but not on the bottom. (under drive, the bottom of the belt is slack ). The spoke on the bottom of the pulley is NOT under load, and as it swings back and up to the top, the load increases to its peak as the belt teeth disengage. 80% of the torque of the motor is therefore concentrated on just ONE QUARTER of the circumference. Thus a properly designed pulley assembly will require EACH spoke to handle the FULL power of the motor. And Then some. Because each spoke is discrete from the rim and each other, each Can and Does move independently... and can not transfer meaningful load to the rest of the assembly. As it drives, it is Not really pushing down on one screw and up on the other. Rather, it is turning the leading screw into the fulcrum of a lever arm as long as the spoke, acting on the trailing screw. Therefore, you can calculate the load on the screw hole by Multiplying the force of the motor by the mechanical advantage of the Leverage the spoke exerts on the screw hole... that is, if the distance from the leading screw hole to the rim of the pulley is 4 times the distance from the leading screw hole to the trailing screw hole, you are multiplying the motor’s force by FOUR TIMES on the trailing screw hole. That is why the trailing hole failed, while the leading screw hole just got enlarged. The reason most lightweight chainrings and cranks have angled spokes is to combat this leverage... to either put the entire spoke into compression, or tension, rather than shear. (Inclined at an angle closer to the vector of peak pull ). If you are going with an assembled pulley... then you should cut the spokes to angle backwards against the pull of the belt... and if possible, make the center collet with a shoulder against which the entire inner edge of the spoke abuts... so that it can transfer load across it’s entire edge area rather than just half the edge area of the holes.

[@hashemamer8515]

I just love and enjoy watching your progress on each and every project you work on.

[@omer531998]

I Actually like the weekly videos, even if they are not finished... I think an upload schedule is really important. anyway, ur videos are great!! i really look forward for the weekend to watch them! keep up the great work.

[@LordDecapo]

after telling myself i was gonna be a patreon and forgetting to for like a month, i finally did it xD keep up your amazing work tom!

[@bigfilsing]

All good stuff. Watching the failure vids is very informative! Just a pity they take so much of your time. Seeing the failure assessment and the following development is really interesting. Keep up the great work. Cheers

[@antor_khan]

I love when things fail! Plz keep making videos on them.

[@erwanbosh3246]

Love your videos, I learn a lot and you really have a talent for explaining something complicated really well

[@martindinner3621]

Honestly, I love to see the failures. We learn as much or more from how things fail!

[@MCsCreations]

Great work, dude! Looking forward to the next video! 😊

[@Tomasxt25]

Always look forward to these videos!!! Good job Tom.

[@slartibartfastm9714]

I really enjoyed this video. I like that you put your wins and fails in the video. Keep it up!

[@Viscontiorama]

Excellent video the excitement of making one and wanting to ride is real. I went the simple way with a hub Motor and tried to ride it without torque arms and spun in the dropouts, severing all the phase wires and halls but i learned a lot rebuilding it. Its never really a failure just a learning experience.

[@christopherpardell4418]

To be extra clear... the spoke is acting like a cantilevered beam subjected to a periodic loading and unloading... like a diving board. The leading edge of each spoke in compression, and the trailing edge in tension. The downward force you cite on the leading screw is prevented from going anywhere by the hub around which the spokes are arrayed... ergo- it has a bearing against which to thrust... but there is nothing to prevent the trailing edge of the spoke in tension from moving away from the hub. With the lead screw hole unable to go very far down, it becomes the pivot point around which the forces impart a moment onto the trailing screw hole... yanking several times the motor’s force on each spoke in turn and then releasing with each revolution. The material you made the arms out of is stronger in compression than in tension and has a low elasticity... such that It deformed plastically under the periodic loading. Your calced safety factor is not there because you assumed the pulley assembly’s members shared the load evenly. They don’t, even in a monolithically cast pulley... but in a pulley made of bolted together parts... load really just can not be counted on being distributed fully thru the various connections.

[@BaselineNL620]

love your video's Tom. Of course I'd like to watch a video every week, but I'm also looking forward to watching more detailed project videos. Keep up the good work!!!!

[@JonPrevost]

Torque for a motor is generally a straight slope. Highest at stall, zero at no load top speed. Hence the perfect parabola HP curve. The brushless motor designs are typically torque limited by the ESC so instead of a perfect slope it looks more like a table that then drops off into a slope. Look at your motor specs for radial and axial loads. You might have damaged the bearing by putting a lot of torque by tensioning the belt. Either support the shaft into double shear, shorten the shaft (unlikely) or completely unload the motor bearings from seeing any radial loads (use a shaft coupler with misalignment or install the motor on elastic mounts. Best of luck! Love the videos.

[@thinkhelpservice]

Thanks Tom for another great video - it’s an honour to be a patreon of your channel

[@marcelcaratus3957]

I love your projects and your approach to problem solving!

[@justtestingonce]

The structural analyses was gold.

[@ARepublicIfYouCanKeepIt]

Hey Tom, it's your channel, so do what works best for you. Those who subscribe and request notifications will eagerly await your next video, as well as all those that follow. Your awesome, so keep up the great work.

[@typxxilps]

It's pretty great to follow your adventures with all its ups and downs or even "flash backs" when you incidently come across reliquies of previous adventures - like that tribochet. Then I was instantly in your previous videos in my mind and how you calculated, measured + improved that tribuchet. And now back in the ebike business until that rc parachuter comes along or whatever adventure. Take your time you need to create the next episode of any of your adventures. Don't hurry, just try to establish a regulary schedule of every 2 weeks or so and if your running out of time just create an improvision , just a simple update video what has happened. Good luck.

[@darren990]

great video tom .a fail is a learning kerv witch only makes you succeed in the end

[@johndoyle4723]

Really appreciate your engineering. Content beats presentation all the time, not criticising your presentation, just saying the content is superb. Some of this should be compulsory viewing for schools, we need to elevate the status of engineers, and you are part of this. Thanks, I have subscribed.

[@The85Maxim]

Your videos have really improved, nice work

[@wangchi623]

I thoroughly enjoy watching the failures as much as the successes. Even more so honestly. Failures make us who we are, but to achieve success without any failures is to achieve nothing at all.

[@Mr-nt8mz]

Thanks so much, Very well detailed and great advices. I've seen all your projects and there are more and more findings each time. Keep going, you're doing something great!

[@BillySugger1965]

It broke? No shit! Keep going Tom!

[@FPVSlacker]

On quadcopters, changing the ESC PWM frequency can move the resonant RPM out of the useable throttle range.

[@sanches2]

Aaand that's how you learn engineering the hard(better) way;) one of the first acronyms we were told while studying FEM analysis was GIGO Garbage In-Garbage Out;) Congratulations on your build!

[@williamwelmans3026]

When in production ' Stanton' would be a good name for your bike !

[@i1cool]

I have really enjoyed this format of video on your ebike. I like seeing how your design changes as you hit problems. It would be sad if you started only doing finished build videos without showing the process in detail.

[@Gribbo9999]

Thanks Tom! Another interesting exercise in practical engineering design.

[@oliverer3]

Yeah don't stop showing the fails they are among the better parts of the videos since those are what you can learn the most from and understand why many elements in the final design ended up as they did.

[@tullgutten]

for future projects might be good to use a tension pulley on the compression side of the belt, not the tension side where the motor pulls on the belt. and have the tension pulley to be moving freely but having a big spring to apply constant tension on the belt as it stretches under load

[@Orbis92]

Very nice build so far :) Maybe a (steel) back plate for those two bolts might helped to clamp the spokes to the ring, so that the forces are transferred through the surfaces instead of the bolt and one side of borehole?

[@keantoken6433]

Try using countersink screws. It mounts flush and it leaves no gaps in the material around the joint, so it's stronger and it won't shift under load. The load is more evenly distributed around the hole so it's stronger.

[@walkerward]

I suggest utilizing hex shaped shafts for applications like this as well as hex bore bearings and pullies to prevent issues with the set screws (grub screws)

[@DylanEdmiston]

You can determine the torque your BLDC motor is producing if you know the Kv and the amps you are applying. Do this by deriving the Kt and multiplying by the amperage. You can derive the Kt from the Kv using the formula KtKv=1 in SI units.

[@halnywiatr]

@ 7:50 Stainless steel fasteners, under pressure, are subject to "galling": a form of cold-welding. One has to use anti-seize compounds, or switch to another material.

[@Scientist9221]

I think the vibration is caused by the mass of the whole thing (motor, bracket) plus the clamping of the mount on the bike frame. M and K, the motor spindle output is the excitation source.

[@rabbitphluff]

You could try calculate the motor torque from kv kt. Provided your motor controller can give you some measurements of the motor current.

[@musicauthority7828]

One of my other favorite channels Trogly's Guitars Show. ran into the same issue with schedulling his videos. until worked out a schedule of no more than one video a wee. which seems to be the best schedule for making You Tube videos.

[@Faith_Family_Firearms_Freedom]

Hang in there. You've come this far, you'll get it.

[@kehnyalexandre5248]

The efforts analysis were very interesting :) Good job !

[@micgent]

Im thinking the Motor Shaft Vibration could be due to the ESC (Electronic Speed Control). It could be resonance but derived from the pulse width switching frequency. Many Variable Frequency Drives have a parameter called Skip Frequency. If for example you experience resonance at 40hz you can program the VSD to avoid that frequency.

[@andrewsnow7386]

It looks like you solved your spoke problem, but if you need more strength here's an idea: In your stronger design, each spoke has a flat on each side where it touches it's neighboring spokes. Instead of a flat you could put a protruding tooth on one side and a corresponding indentation on the other. If the spokes are accurate enough, this toothed connection between spokes would take a good bit of load off of the bolt holes. Unfortunately, the wider bolt spacing on your stronger spokes leaves you with no room to add an indentation. So, let me give you one more idea. I assume that toque on the pulley in the reverse direction (caused by regeneration) will be small compared to the maximum torque in the forward direction. If this is true, then the "tooth" I mentioned above could just be a small triangular addition to the trailing corner on the inner end of the spoke. A corresponding chamfer would be made on the other inner corner of the spoke. This would only help with torque in the one direction, but if kept small would probably not hurt when torque was applied the other way.

[@erlinghagendesign]

thks Tom. Very good explanation, simulation & testing.

[@bertusbertus4657]

Love youre video’s, I am and will always be a loyal viewer 👍🏻 Keep up the good work

[@gusos234]

Nice! Good job. Love your engineering approach.

[@theodornitu]

Keep the failure videos mate! Its all about learning!

[@13ahab]

Maybe soft mounting the motor will stop the vibrations or reduce it

[@Hoggdoc1946]

Too much torque for that idea.

[@alibro7512]

More nice work and fault analysis, liking the new pulley design. I'd have just clamped the larger pulley to the spokes. But then again I used a car alternator to build my ebike so whatever you do don't ever listen to me. Keep up the good work.