Years ago there was a Visible V8 model that had a starter that consisted of a can motor that turned a sun gear that meshed with 2 planet gears. The planet gears meshed with 2 internal gears with different tooth counts. One internal gear was stationary and the other one was connected to the starter pinion. The starter pinion meshed with the engine flywheel.
For years I have wondered how robots with compact reduction gear assemblies were able to work without backlash. I had always assumed there was a sun gear assembly inside, so it never occurred to me it was a "harmonic drive", which I heard of but didn't grasp the meaning. I learned so much today and it was awesome. Thank you very much, I needed that! :)
I had a great “Ah Ha” moment about 6 or 7 minutes into the video. I’m a now retired electronics technician who used to work in the production of printed newspapers. Equipment from a company called Ferag used harmonic drives and when we were trained on it the instructor told us what it did but couldn’t explain how it did it. To him it was a magical engineering marvel. In the years that followed we repaired them quite frequently. Usually the Flex Ring would crack and we disassemble the unit and replace it. I had a fair understanding of how it worked after working on them but you, my friend, brought it all together. I’m going to forward your video to my former coworkers who still have to deal with it. I’m sure they’ll appreciate it. Thank you.
A possibly belated, but no less heartfelt and sincere thanks for taking the time and effort of making this absolutely EXCELLENT video. Explaining a complex subject matter in a VERY clear concise and approachable manner. It is in my opinion "pearls" like this video that makes Y.T. worth while. Best regards.
Super great explanation. One would think that the flex spline gear would fatigue over a short time, but they're so widely used in so many applications that it must not be an issue. Thanks for the great video demonstration!
I subscribed because you talk slow enough for someone to follow what you are saying and you leave the video on what you are showing long enough for the viewer to follow it.
Considering buying a telescope mount that works on this principle and wanted to understand it. Your video helped a lot. The advantage of very low backlash in astronomical mounts is significant, as well as the reduced need for counterweights on the mount. Thanks very much.
Ha! We must be looking at the same new ZWO mount! There are also others on the market that now have me looking into this tech more. This video explained it perfectly.
@@lizards821 You're right! Check out the cloudynights discussion. It's the PEC that's inherent in these drives that convinced me to not buy it. Looks like a good mount for visual, but not for DSO astrophotography, which would be my primary use of it. Leaning toward the EQ6-R Pro when they come back on the market.
@@cmahar3 yikes yeah spending $2k for a mount that cannot really do dso is kind of a bummer, especially considering the eq6r pro is less than that. Cuiv the lazy geek here on yt also has some videos on his as well.
@@lizards821 Right? All DSOs aren't out of the envelope of this mount, just the small dim ones requiring focal length longer than 900mm. OTOH there are literally no EQ6R-Pro mounts available in the US or Canada right now due to supply chain issues, and there won't be for months.
Zero backlash & fixed timing... 2 great attributes for a gearbox... 🤨 a lot of people don't realise just how important backlash , or rather lack of it , is.. anyone with a milling machine who trys climb-cutting better have NO backlash in their table feed... 😰 Great description, the use of the straight racks initially helped greatly to understand the theory behind these rather exotic & quite expensive units... 🤗 😎👍☘🍺
When you say, "fixed timing" do you mean the input side is directly proportional to the output side? I saw cyclonial might have a problem in this regard ( because the input side to output side is not strictly linear because each teeth engaging is not directly proportional?)
Thanks for the explanation. When I took aircraft maintenance our instructor had us make our own vernier scale using two pieces of paper with marks on their edges. It opened our eyes to the concept of a vernier scale. Later we had to manipulate a vernier coupling to change timing which was very simple for us. This differential of gear teeth I instantly understood from that course I took over fifty years ago.
In the '70s, as a 12 year old, I had a Visible Wankel Rotary Engine model which was driven by a planetary gear harmonic drive. I always assumed that this was how it worked, I was never sure until I saw this.
This is the most amazing and useful video i have seen in a long time. Thank you for explaining this. I was really struggling to understand exactly how it works. You are an awesome teacher.
Thanks for the concise explanation. I can see that these drives have multiple applications beyond the world of robotics. As an astrophotographer who deals with backlash on a seasonal basis (ambient temperature variations) this technology would be exceptionally well suited to telescope drives. My impression is that this type of mechanism would be less prone to backlash due to temperature variation. Chhers!
Wow, you're a great teacher, your video is terrific and I now know something completely new about gear drives. Years ago I got a fanuc welding robot arm and was amazed at the zero backlash on the joints but never knew why it was possible until now. As for how to get 2 more teeth with the same pitch, it's hits me now that the outer ring is naturally LONGER than the inner one, hence can have 2 more teeth in its' path. However, sizing up the tooth depth to accomodate the mating, etc is a challenge.Thanks for this explanation and I'll look at more of your videos in the future.
Superb video! Thank you! Now I know why grease for our Yaskawa robot harmonic drives costs quite a dollar. Thare is a company Harmonic drive, that is making everythig around this technology.
Thank you very much for a very simple explanation of strain wave drives. One of the newer places that these drives are starting to be used is in astronomy, more specifically astrophotography. Astrophotographers are always looking for lighter weight, more powerful, more reliable and less power consumption in their gear, since often time hobbyist astrophotographers are out in the middle of some open field, far away from any power. For the most part, telescope mounts fall into two categories, Alt/Az, or Altitude Azimunth and EQ, German EQ which means German Equatorial mounts For astrophotography, EQ mounts are much more common, albeit much more expensive. You can align one axis to the North Star, Polaris, and the mount will rotate around that point in the sky, and since all the stars and things in space also rotate around it, once you've selected your target, the mount tracks around the North Star, keeping the object in the center of the scope. Strain Wave drives are now offered by two companies, ZWO and iOptron. Usually, a normal EQ mount requires a counterweight and shaft to balance the load on the 'Right Ascension axis, which is the axis pointed at the North Star. Having the system balanced keeps down tracking errors. The Strain Wave drive eliminates the need for the counterweight (up to a certain payload), thereby reducing the entire weight of the mount. It also tracks better and has zero backlash, which is something astrophotographers also are interested in. So, yeah, Strain Wave mounts are coming, and they are going to be the future of hobbyist astrophotography. Because of you, I know a lot more about strain wave drives now than I did 45 minutes ago!
They are starting to be used in astrophotography-mounts, that’s how I got interested in the topic. No backlash is the magic that‘s so important in this area. Great explanation, that’s why they are so,expensive
I can't thank enough to the person explaining very beautifully the concept of harmonic drive so good video ❤️❤️ love it it just instantly clicked in my mind how the mechanism works after seeing the demonstration
This is an excellent video . I was having serious difficulty understanding this drive and your explanation brought it all together for me. I commend this instructor profusely.
To everyone wondering if you can use spur gears on the bearings instead of a flex spline, the answer is: yes. I was curious about this as well, so I drew up a harmonic drive in Fusion and 3D-Printed a model that uses entirely 3D-Printed parts except the bearings, which are fidget spinner bearings. My tolerances leave a lot to be desired, which may hide the reason for using flex-splines instead, but it is a fully functional gear reduction that uses spur gears all round and no belt/compliant mechanism.
Jake, I would love to see your model. I would like to build a drive and am researching different methods right now. What you describe seems interesting....
Goog question. I guess with a more rigid flex it can engage more teeth. I also think the "real" harmonic drive do not use rollers inside but an ovoid slipping within the "belt" edit: it is an elliptic bearing: ruclips.net/video/bzRh672peNk/видео.html
Oddly enough when you were talking about that invention back in the 50s that explains probably why my father when I was a child was giving me an explanation how bigger gears than little gears if depending on what's going on with speed and motion you can probably run a car at 55 miles an hour with a toy motor it all depends on how you arrange the gears and that explains what he was trying to show me when I was a child he was trying to envelope a sense of science I guess when I was a child but it took off many years later it took off thank you
You give an excellent description of how the flexspline is a wedge that aligns the stator and output gears in the model but when you go to a real world application the stator and output are no longer wedged into alignment. Obviously they can't be as they are completely different gears. This looks like a similar but different mechanism. I would like to see a model that accurately represents the Fanuc robot drive.
Nice video! Looking at these drives I thought that instead of having the flexible gear to wedge the stator and output gears, why not have a plantetary/harmonic hybrid? It would be like a normal planetary setup, but instead of the drive going through the planet gears, the planet gears would only do the job of the flexible gear in a harmonic drive setup, becoming the wedging force to do the reduction, while transmitting the force/torque. There would no longer be a need for the traditional sun gear as in a plantetary setup, so it could be omitted. The difference in gear teeth needed for this to work as a harmonic drive could be achieved by making the outer part of the planetary drive (is it called the ring gear?), in two pieces with a different number of teeth. These two ring gears would act as the stator and the output respectively, connected by the aforementioned planet gears (which may need to be slightly elongated to allow for adequate meshing contact between the two ring gears). By using planet gears to do the job of the flexible gear, it negates the need for it to be flexible, removing the weak link. Also, if you adjust the teeth size to outer ring gear diameter ratio, you could have more than two spots where the teeth "harmonize" allowing for greater force transfer, while dispersing the load for better longevity. Just a thought...🤔
The gear wheels and bearings would be under a lot of load and subject to much more wear. I would guess that you would also need a brake mechanism if the bearings are freewheeling when not being loaded by a drive... But not 100% sure on that!
Your setup was so clear that it was immediately easy to comprehend. Good teacher.
Agreed, reminds me of the old Docs from the 40s explaining planetary gears transmissions and rear differentials
Years ago there was a Visible V8 model that had a starter that consisted of a can motor that turned a sun gear that meshed with 2 planet gears. The planet gears meshed with 2 internal gears with different tooth counts. One internal gear was stationary and the other one was connected to the starter pinion. The starter pinion meshed with the engine flywheel.
He started explaining, and I couldn’t understand why he had such a hard time understanding it in school lol. It was so simple.
That's the best explanation I've seen so far. Took a good deal of effort to setup.
For years I have wondered how robots with compact reduction gear assemblies were able to work without backlash. I had always assumed there was a sun gear assembly inside, so it never occurred to me it was a "harmonic drive", which I heard of but didn't grasp the meaning. I learned so much today and it was awesome. Thank you very much, I needed that! :)
I had a great “Ah Ha” moment about 6 or 7 minutes into the video. I’m a now retired electronics technician who used to work in the production of printed newspapers. Equipment from a company called Ferag used harmonic drives and when we were trained on it the instructor told us what it did but couldn’t explain how it did it. To him it was a magical engineering marvel. In the years that followed we repaired them quite frequently. Usually the Flex Ring would crack and we disassemble the unit and replace it. I had a fair understanding of how it worked after working on them but you, my friend, brought it all together. I’m going to forward your video to my former coworkers who still have to deal with it. I’m sure they’ll appreciate it. Thank you.
A possibly belated, but no less heartfelt and sincere thanks for taking the time and effort of making this absolutely EXCELLENT video. Explaining a complex subject matter in a VERY clear concise and approachable manner. It is in my opinion "pearls" like this video that makes Y.T. worth while.
Best regards.
Çok teşekkür ederim. Mükemmel bir çalışma. Onlarca video izledim fakat yeterince anlayamamıştım. Çok başarılı anlatım.
Super great explanation. One would think that the flex spline gear would fatigue over a short time, but they're so widely used in so many applications that it must not be an issue. Thanks for the great video demonstration!
We use these drives in our surgical robots. Love the clear explanation and linear props to illustrate the basic physics. Thank you.
Great explanation. Now I understand the mechanics behind my new telescope mount drive. Very impressive!
Best harmonic drive mechanical explanation I've seen (out of at least a dozen I've come across)
Man i wish i had a teacher like this guy, school woulda been great
I've read how this drive works multiple times but never were able to visualize how it works. It was a mystery to me up to now. Great teacher!
I finally understand harmonic drives. In 12 minutes. Man that's stellar.
I work for Harmonic Drive and it really doesn't surprise me that these things last. Much care an precision goes into making these.
I understand it immediately after your demo with those straight gear. Very clear explaination.
Shared this video to my robotics class. Far and away the best video explaining how these drives work from the 5 I watched before this.
I have never even heard of these mechanisms before but I'm super glad I stumbled on this video. That was fascinating!
I subscribed because you talk slow enough for someone to follow what you are saying and you leave the video on what you are showing long enough for the viewer to follow it.
Considering buying a telescope mount that works on this principle and wanted to understand it. Your video helped a lot. The advantage of very low backlash in astronomical mounts is significant, as well as the reduced need for counterweights on the mount. Thanks very much.
Ha! We must be looking at the same new ZWO mount! There are also others on the market that now have me looking into this tech more. This video explained it perfectly.
@@lizards821 You're right! Check out the cloudynights discussion. It's the PEC that's inherent in these drives that convinced me to not buy it. Looks like a good mount for visual, but not for DSO astrophotography, which would be my primary use of it. Leaning toward the EQ6-R Pro when they come back on the market.
@@cmahar3 yikes yeah spending $2k for a mount that cannot really do dso is kind of a bummer, especially considering the eq6r pro is less than that. Cuiv the lazy geek here on yt also has some videos on his as well.
@@lizards821 Right? All DSOs aren't out of the envelope of this mount, just the small dim ones requiring focal length longer than 900mm. OTOH there are literally no EQ6R-Pro mounts available in the US or Canada right now due to supply chain issues, and there won't be for months.
Hands down ...the best video I have seen on harmonic drive.
You Sir defogged my mind in 12 minutes on harmonic drives, THANK YOU.
Zero backlash & fixed timing... 2 great attributes for a gearbox... 🤨 a lot of people don't realise just how important backlash , or rather lack of it , is.. anyone with a milling machine who trys climb-cutting better have NO backlash in their table feed... 😰
Great description, the use of the straight racks initially helped greatly to understand the theory behind these rather exotic & quite expensive units... 🤗
😎👍☘🍺
When you say, "fixed timing" do you mean the input side is directly proportional to the output side? I saw cyclonial might have a problem in this regard ( because the input side to output side is not strictly linear because each teeth engaging is not directly proportional?)
goes from stories and anecdotes about harmonic drives to explaining them at 2:00
WOW What an amazing explanation. Thank you so much.
Thanks for the explanation. When I took aircraft maintenance our instructor had us make our own vernier scale using two pieces of paper with marks on their edges. It opened our eyes to the concept of a vernier scale. Later we had to manipulate a vernier coupling to change timing which was very simple for us. This differential of gear teeth I instantly understood from that course I took over fifty years ago.
In the '70s, as a 12 year old, I had a Visible Wankel Rotary Engine model which was driven by a planetary gear harmonic drive. I always assumed that this was how it worked, I was never sure until I saw this.
This is the most amazing and useful video i have seen in a long time. Thank you for explaining this. I was really struggling to understand exactly how it works. You are an awesome teacher.
Thanks for the concise explanation. I can see that these drives have multiple applications beyond the world of robotics. As an astrophotographer who deals with backlash on a seasonal basis (ambient temperature variations) this technology would be exceptionally well suited to telescope drives. My impression is that this type of mechanism would be less prone to backlash due to temperature variation. Chhers!
Wow, you're a great teacher, your video is terrific and I now know something completely new about gear drives. Years ago I got a fanuc welding robot arm and was amazed at the zero backlash on the joints but never knew why it was possible until now. As for how to get 2 more teeth with the same pitch, it's hits me now that the outer ring is naturally LONGER than the inner one, hence can have 2 more teeth in its' path. However, sizing up the tooth depth to accomodate the mating, etc is a challenge.Thanks for this explanation and I'll look at more of your videos in the future.
Thank you for the clear demonstration of the harmonic drive!
I appreciate the clear explanation and effort of building the demo rigs.
This is the clearest demonstration and explanation I've seen in a long time. Thank-you.
I have heard of this but had never had an explanation. You provided a very good explanation.
Superb video! Thank you! Now I know why grease for our Yaskawa robot harmonic drives costs quite a dollar. Thare is a company Harmonic drive, that is making everythig around this technology.
Thank you very much for a very simple explanation of strain wave drives. One of the newer places that these drives are starting to be used is in astronomy, more specifically astrophotography. Astrophotographers are always looking for lighter weight, more powerful, more reliable and less power consumption in their gear, since often time hobbyist astrophotographers are out in the middle of some open field, far away from any power.
For the most part, telescope mounts fall into two categories, Alt/Az, or Altitude Azimunth and EQ, German EQ which means German Equatorial mounts For astrophotography, EQ mounts are much more common, albeit much more expensive. You can align one axis to the North Star, Polaris, and the mount will rotate around that point in the sky, and since all the stars and things in space also rotate around it, once you've selected your target, the mount tracks around the North Star, keeping the object in the center of the scope.
Strain Wave drives are now offered by two companies, ZWO and iOptron. Usually, a normal EQ mount requires a counterweight and shaft to balance the load on the 'Right Ascension axis, which is the axis pointed at the North Star. Having the system balanced keeps down tracking errors. The Strain Wave drive eliminates the need for the counterweight (up to a certain payload), thereby reducing the entire weight of the mount. It also tracks better and has zero backlash, which is something astrophotographers also are interested in.
So, yeah, Strain Wave mounts are coming, and they are going to be the future of hobbyist astrophotography. Because of you, I know a lot more about strain wave drives now than I did 45 minutes ago!
Easist tutoial that I 've ever got.
This is how the Sumitomo Cyclo drives work. Very interesting and well done
This was fascinating. I've seen it explained a dozen or so times but this is the first time I've actually understood it.
Thank you!
Very clear, well done, finally grasp it thanks to the linear version. Thanks!
They are starting to be used in astrophotography-mounts, that’s how I got interested in the topic. No backlash is the magic that‘s so important in this area. Great explanation, that’s why they are so,expensive
thank you for an excellent 👍 class, I have never seen a harmonic drive in rl, but now I know what it is. greetings from Cape Town South Africa.
I can't thank enough to the person explaining very beautifully the concept of harmonic drive so good video ❤️❤️ love it it just instantly clicked in my mind how the mechanism works after seeing the demonstration
This is an excellent video . I was having serious difficulty understanding this drive and
your explanation brought it all together for me. I commend this instructor profusely.
Fascinating. Great explanation. Harmonic drives are showing up in telescope mounts and I wanted to see how they worked.
To everyone wondering if you can use spur gears on the bearings instead of a flex spline, the answer is: yes. I was curious about this as well, so I drew up a harmonic drive in Fusion and 3D-Printed a model that uses entirely 3D-Printed parts except the bearings, which are fidget spinner bearings. My tolerances leave a lot to be desired, which may hide the reason for using flex-splines instead, but it is a fully functional gear reduction that uses spur gears all round and no belt/compliant mechanism.
Jake, I would love to see your model. I would like to build a drive and am researching different methods right now. What you describe seems interesting....
Thank You! I was wondering 😊. I love your simple description. You haven't by chance posted your STLs somewhere? 😊
Terrific illustration. Thanks for posting the video.
man this was a perfect explination, very good job! amazing drive motor design... the minds that come up with these things
That was SO well explained, even a thickie like me got it.
It looks like a perfect job for a wire EDM machine. Great explanation. Thank you.
This is the best explanation of this mechanism I've ever seen. Thank you!
Love it!!! I need to make some of these but specialized use.
Brilliant explanation, thank you for the clarity! This concept is really flexible (pun intended!)
Best explanation I've ever seen!
This guy is a great explainer. Thanks for the video.
Your explanation was very easy to understand. Thank you
OMG THANK YOU… this actuator type has been _wrecking_ my brain for the last two weeks!
Fantastic explanation and the hardware was really good. I now know 'Harmonic Drive' has nothing, at all, to do with music.
Awesome Demonstration, you wrapped up the idea in a beautiful simple was with many tools
Great explanation. Factories replacing every year or few years would explain cheap used robots.
Fasting drive and very clear explanation thank you!
This is the best explanation I've seen. I'm wondering why use a flex instead of just smaller gears.
Goog question. I guess with a more rigid flex it can engage more teeth. I also think the "real" harmonic drive do not use rollers inside but an ovoid slipping within the "belt"
edit: it is an elliptic bearing: ruclips.net/video/bzRh672peNk/видео.html
and with the right number of theeth maybe have more points of "harmony" in the gears?
Because the teeth only match up in 2 places, so the inner "flex" gear can only be in contact in 2 places
Oddly enough when you were talking about that invention back in the 50s that explains probably why my father when I was a child was giving me an explanation how bigger gears than little gears if depending on what's going on with speed and motion you can probably run a car at 55 miles an hour with a toy motor it all depends on how you arrange the gears and that explains what he was trying to show me when I was a child he was trying to envelope a sense of science I guess when I was a child but it took off many years later it took off thank you
The best explanation of this drive. Point!
Greetings from Munich, Tom.
Glad to see you up and running again. Be well.
I must subscribe to the channel. Immediately and deeply attracted by the awesome demonstration and teaching. Thank you!
Most detailed and easy explanation of harmonic gear i've ever seen
This is a great explanation - well done!
Cool video! Wanted to buy one of these robot arms recently but than I looked at the price...
Now I’ve decided to just build one!
You give an excellent description of how the flexspline is a wedge that aligns the stator and output gears in the model but when you go to a real world application the stator and output are no longer wedged into alignment. Obviously they can't be as they are completely different gears. This looks like a similar but different mechanism. I would like to see a model that accurately represents the Fanuc robot drive.
You explain extremely well!
And your pronunciation is so clear. Cheers mate!
This video is incredibly well presented.
Best explanation and drive model ever!
Clear explaination and great video. Thank you
It's so excellently explained! God Job!
Great model and explanation.
Great teaching! I have learnt a lot. Thank you.
that was interesting. never heard of a harmonic drive but could see how durable and long lasting it could be. thanks for the info!
New subscribers earned ! Much love from 🇺🇸and 🇨🇦
One more thing I never knew I wanted to know.
Thanks random smart dude on the internet.
Excellent, thanks for taking the time to make this!
The explanation is so clear and fantastic, thank you!
Anyone watching this might want to actually google Ian Juby before deciding how much you trust his teaching, or want to support his business/videos.
Outstanding it is Crystal clear now
Nice video!
Looking at these drives I thought that instead of having the flexible gear to wedge the stator and output gears, why not have a plantetary/harmonic hybrid?
It would be like a normal planetary setup, but instead of the drive going through the planet gears, the planet gears would only do the job of the flexible gear in a harmonic drive setup, becoming the wedging force to do the reduction, while transmitting the force/torque. There would no longer be a need for the traditional sun gear as in a plantetary setup, so it could be omitted.
The difference in gear teeth needed for this to work as a harmonic drive could be achieved by making the outer part of the planetary drive (is it called the ring gear?), in two pieces with a different number of teeth.
These two ring gears would act as the stator and the output respectively, connected by the aforementioned planet gears (which may need to be slightly elongated to allow for adequate meshing contact between the two ring gears).
By using planet gears to do the job of the flexible gear, it negates the need for it to be flexible, removing the weak link.
Also, if you adjust the teeth size to outer ring gear diameter ratio, you could have more than two spots where the teeth "harmonize" allowing for greater force transfer, while dispersing the load for better longevity.
Just a thought...🤔
I appreciate the effort you put on to explain. Well done!
Sir, you are a life saver.
Been wondering how that works for a while. Thanks for making the video and explaining it
Awesome explanation. Nothing to say other than many thanks !
Talk about gear reduction for precise and extremely fine movements....fantastic design, never thought about such an idea.....until now.......
Very well demonstrated. Thank you
Very nicely explained.
Great presentation!
Great explanation.
Thank you. I learned something new today.
Such an amazing demonstration!
Never heard about harmonic drive until recent, when Trek introduced their e-bike with harmonic-drive ))
Excellent demonstration! Thank you so much!
Excellent explanations !!!
Never heard of it, very interesting.
I wonder why they don’t just use 2 opposite gearwheels instead of the flexspline?
The gear wheels and bearings would be under a lot of load and subject to much more wear. I would guess that you would also need a brake mechanism if the bearings are freewheeling when not being loaded by a drive... But not 100% sure on that!
You are a great teacher, thank you.
Amazingly educational, I 100% get it now