Strange, I am following along perfectly. Though I do have problems following along with all the jargon for code, and coding programs. This is a breath of fresh air for me, compared to the other videos.
I started out in the computer industry as a field service engineer in 1970 and some of the mechanical contraptions around then were unbelievable, I found electronics much easier to follow. Here we are over 50 years later and I'm still discovering these amazing mechanical devices.
correct, I see no reason why this should not work more perfect with real gear tooth design instead of these round teeth. But certainly much more efforts. I have seen this only once. All other designers do it as you do (with the half circles as teeth)
I’d like to to point out that this is not an actual cycloidal transmission, even the animation doesn’t not show it correctly. The cycloidal disc has a specific shape to it which can’t be designed with a basic cad sketch - nonlinear. It has to be calculated and interpolated (e.g. matlab to dxf to cad). I built a full metal version for a robot link myself (video..), there is no room for shape imperfections :) The actual shape will improve output speed consistency, load distribution around the circumference. In addition: Multiple disc will help to reduce load induced eccentricity and vibration..improve the efficiency (back drivability). As a hint: every roller has contact to the cycloidal disc at any position in rotation. Might seem difficult, it can be described - for “each“ position - by means of ruler and compasses though
Is there a technical name for this type of 'cycloidal' variant, or is it just a bastardized version that only works if the materials are somewhat compliant or have large tolerances?
@@rdyer8764 I‘m not aware of a suiting name. It somehow appears as a cycloidal without being a cycloidal :) The cycloidal itself defines a specific shape that’s created by rolling one shape in relation to an other one and tracking a point one the moving element- e.g. circle over circle or circle over a straight line.
@@rdyer8764 Hah. Unlikey, I just happened to have been working on an anti-backlash variant of Paul Gould's work after printing his version last week. In fact, Paul Gould includes his inventor files and the equation is embedded in the defining profile for the disks. I ended up looking up and re-doing it myself because I don't like using equations I don't understand (also - I couldn't get the ratios I wanted to work correctly, and wanted to understand why!).
Yes yes yes, i love seeing These cycloidal bois popping up all over TH-cam. I am currently working on an actuator where i integrated a 16:1 cycloidal gearbox into the stator bore of a 8108 BLDC motor to make it super compact.
I don't know if I can hear it because of having young ears, but I love the high pitched sound that the motor makes when you were initially testing it - very cool.
A cleverly designed 2 stage belt system can be very compact and strong. The trick is to use a very small difference in cog diameter, have the second stage coaxial with the first stage, and then spin the casing that holds the cogs. So the casing becomes the input shaft, one of the cog shafts becomes the casing, and the other (coaxial) cog shaft becomes the output shaft.
I recently experimented with cycloidal drives myself because I find the principle really fascinating. I didn't do it with such a high-torque or clean design but here's two interesting things I discovered: If you use a correctly calculated cycloidal shape with well-tuned tolerances you can *drastically* reduce the eccentricity(wobbling movement). This not only reduces the strain on the motor and other parts, it also allows for more compact designs as - like you showed in the video - the holes for transmitting the movement from the gear to the output shaft depend heavily on the eccentricity. The drawback of this is of course that tolerances become more significant. The second thing is probably not as relevant for your project because it's more suited for high gear ratios and hurts the ability to backdrive the mechanism, but double-staged cycloidal drives can be simpler to print and build as the output is automatically a non-wobbling rotation without the need of this transmission via holes in the cycloidal disk. So it can again be made smaller. I combined those two aspects to print a tiny double-stage gear with a ~1:1000 reduction, with an eccentricity of just 0.6mm! It's not very practical but it was more of a quick feasability experiment and a lot of fun to make, and interestingly works more smoothly than my failed first try using a single stage.
Absolutely fantastic engineering. This is the kind of video that inspires people to learn... well everything, physics, math, statics, dynamics. It's amazing what youtube brings to the world through intelligent creators like you.
I especially liked this video, James! The way you walked through the problem, iteratively introducing each part of the solution was very informative and satisfying.
Hey, I did a version of a Cycloidal Gearbox with all printing files available and a Fusion 360 script which lets you create the reduction ratio on the fly... it is backdrivable! I am a big fan of Cycloidal Drives! Keep it up!! 😀
Thats nothing xD I saw CNC-machines that shook the building they stood in because they accilerated and stoped so fast^^ The building was checked regulary to withstand it but it was crazy. They once tested a machine not bolted to the floor and it moved like an arms length in a few minutes.
@@JL-pc2eh Your run of the mill Haas has to be anchored to the concrete beneath because the rapids produce enough inertia to rock the machine when it comes to a stop. It is one of their huge downsides. Higher quality machines built with larger and heavier frames don't suffer from the same rigidity issues. Even if the Haas is anchored, the vibration from the lack of dampening will translate into surface finish issues on the part being machined.
I got interested in these Cycloidal drives to use for a self built CNC lathe for the C-axis. It would have to be clutched to the spindle when activating C-axis. I think you could use the same motor for normal spindle drive (high speed) and mechanically shift to C axis mode (high rigidity, low speed positional control). The reason to use a cycloidal gear is that it has almost no backlash and you can get very high reduction and rigidity (if made from something like steel, not PLA, and with tight tolerances). The point is however, on a lathe you often want a through spindle bore. The cycloidal gear would need to have a hole in the middle and I think I have found a way how to do it. Take a look at the output shafts. They basically are excenters aswell, so you could lose the excenter in the middle. Also those output shafts (that are the input as well) don't have to be inside of the cycloidal disc itself, but imagine a disc that does the exentric wiggly thingy (not actually rotating) and the cycloidal disc is "glued" onto it. Then the outer case actually becomes the driven output. Just some ideas. First idea works well in CAD, second one I'll have to dive in to and do some designing.
Cycloidal drive is basically a lob sided subset of planetary gear drive method. Planetary gear set so much stronger, balanced, tighter, efficient and reversible.
It's time people switched to bearings pressed onto dowel pins. They're mass-produced precision parts, and all they need is a reamed hole in the plastic parts to receive them for repeatable interference fit
CNC mill a version of it out of metal when you have a model that works like you want and use that to make it both smaller and more solid. Epic cycloidal gear by the way :D
@@santosvella It's good if you want to do testing. One you have something that works, then you go for the milled metal parts. If that works or not, you tweak it, rinse repeat and soon you have your working device or prototype.
@@santosvella Maybe one day soon we'll get new 3D printers that are able to do multi materials that include ceramics and metals. I know we can do that now with some really expensive gear, but imagine what we could try with 3D printers that could created items of durability. I saw this demo of a very very custom and very advanced 3D printer being researched that more or less could do any material. It could even do 3D milling. It was insane and the cost was in the millions. But we'll get there one day.
That's really neat! I'd never even heard of a gearbox like this, I just thought it was going to be a planetary gearbox. Thank you for introducing me to a different type of drive that can be 3d printed, and looks so interesting when it's running!
Since I recently got a 3d printer, I now fully realize just how much you are able to get done on one within a week. A lot of my prints have averaged at 24 hrs per print. But even with smaller prints, they take longer than I thought. You have several printers now to help you get more done, but even with 1 printer, you seemed to work fast.
Try 1mm nozzle and either .25mm or .4mm layer height, 45mm/s, 210-220C for PLA. Thinner layers allow steeper unsupported overhangs. Supports can add a lot of print time and material use, so design to minimize them. If you have something high up on a model that needs support, see if you can build one in that angles up at 45 degrees from a nearby surface. Much more efficient than a tower all the way from the build plate.
Hi James, you can totally get to 10:1 reduction if you use a pulley force multiplier. Essentially if you replace a big pulley with a large bearing fix one end of the belt back on the body while putting an idler on the leg so that for 2 times the movement of the belt you will have 1 time the travel of the leg.
For a similar result, but with everything running perfectly "round" have a look at "Split-Ring Epicyclic Gear" (or "differential epicyclic gearset", "compound-planet epicyclic", lots of names for the same device). It is also back-drivable (but there is more friction). You might also consider the "Strain wave gearing" that is also compact, has massive reduction-ration and no backlash (and is supposed to be back-drivable, even if this doesn't seem obvious) ; it is 3D printable but requires one "gear" to be printed with TPU or equivalent, because is relies on deformation to transmit the motion.
Fantastic video! This is a brilliant explanation of both the function of a cycloidal drive AND your thorough design and iteration process. Really like it - looking forward to seeing v2!!
You can use M3 of M4 bolts of 12.9 steel quality instead of M6 overkill bolts. Smaller bearings would also allow you to make the device much smaller and lighter for a better impulse response. Looking forward to see it in action!
Im no engineer James but I am a mechanic and we use molybdenum disulfide grease for CV shafts, diff installs and I rebuild my old tools and use it on the sintered gears. My theory is because of the nature of that shit, moly grease should be perfect for a 3d printed gearbox if you use hard-wearing plastics because it'll soak up into the print lines and it sort of embeds the gears with a harder metal so they last longer. I don't understand this as I say I am a humble mechanic and I know near to nothing about 3d printing but I hope that this may help in future. Love Owen.
Since you're sticking the shaft through the center with a cam To stop the vibrations you could mount a weight on the shaft that matches the weight of the gear and stick it 180⁰ out of phase. That way you don need a crank that has to go through two gears. Though getting them balanced perfectly would be difficult. (but you do have the sauce for that in the current design due to the cutout hole)
Make the cam shaft out of metal. Instead of a straight pole off center, make a centered pole with a kink. This will also make it simpler to secure on the other end. The craftsmanship is good enough as is for the rest to hold up to higher torque.
I am so glad you are designing and testing these types of gears. Dare I say you are putting the ole Bruton spin on it (pun intended). Looking forward to next version!!
I thought that cycloidal gear reductions couldn't be back-driven, but I was reaching that conclusion based on OskarPuzzle's "11 million to one gearing". It's nice to be able to update my mental models.
James, I am just sharing my input, take it as my opinion and nothing else, You know I have been following your channel for a very very very long time, this video and last few for that matter, the way you have been producing (and or scripting) them, they are sounding more and and more like a Tom Stanton video's, There is nothing wrong with Tom's videos he has his own thing going on, he is just not everyone cup of tea, you have almost 1M subscribers because of your energetic energy and your brilliant approach to accomplish the project at hand, which was reflected in the way you made your video's, that is why we are all still subscribed to you, you are so close to the 1M, now is no time for to change. I and the many thousands of us, that have been subscribers before you had even 100k subs, all want to see you hit that Millon sub.
@@jamesbruton It is none of my business to suggest anything, as you have already surpassed our expectations and then some, James, you have shown us years ago how brilliant, you and your approach is, you have nothing to prove to us, we already know all that about you. I do understand your point, So perhaps the answer you seek is in the past, as of late, your average view count per upload, has been somewhere between 50k to 90k some a little more some a little less, however, go back 2 or 3 years it is more like 90k to 200 plus k, Perhaps it's not your "balance" but the projects? don't forget most of us AKA the loyal subscribers that have been around for the last 7 or 8 years, are old dogs, we need to be stimulated with diversity loll Take Collin, for example, none of his video's features the same project more than one or two video's, sure he will go back and revisit them now and again. IDK Perhaps bring back that Arty hottie maker friend of yours, on videos more often, mix it up a bit, nothing brings views like a hot maker chick as an assistant haha. JS, James, your videos will always get a like from me.
I look forward to seeing version 2. I certainly think once you sort out some of the bugs and create a good design it will work well for lots of your projects.
You previously had issues with the motors in Opendog 2 heating the plastic, so you fitted those metal plates to dissipate the heat. Might be worth doing similar again.
Really cool project and your explanation (step by step) is 10/10 !!!!! Just one recommendation. Throw this 3D printer in the thrash and get a cheap Creality Ender 3, you won't believe how much better it is :)
This is so cool! I've been thinking that cycloidal drives would be perfect for OpenDog for a while, but I always figured either there was some missing feature or you'd get around to them eventually. I'm really excited to see V2!
This japanese invention used in Hajabusa blanes. Usually has two inner teeth in 180° ankle from each other to reduce resonance, and tear when there is allways atleast 2 inner teeth touching outer teeths in opposite sides. The durablity is better.
While the cycloidal drive option is a really nice one, I'm personally not convinced that you couldn't reach the same goal with a planetary gear set. Regardless though.. I love the solution :)
Think this could use some M10 smooth rod: - Ditch the exterior bearings and run the rotor directly up against the rod. Rotot on steel + silicone lube should be fairly low friction - Same for the bearings inside the rotor: just put small smooth rods through each hole - Finally, even the centre axle could be replaced. Then add a 3D printed cam and drill a fixing bolt through the rod = smaller, fewer parts by ditching all the bearings and easy enough to build if you have a rotary tool with a cutting disc
You could save a lot of space by replacing the ball bearings on the ring and the output disc with plain bearings (aka bushings) running on smooth steel shafts. They can be 3d printed from nylon or graphite filled pla. Obviously this arrangement will have a shorter service life and more friction but the cost, size and weight savings may outweigh that, especially since well designed plastic plain bearings actually last a really long time.
I'd be interested to see James design and build his own version of a 3D printed quadcopter based on the Arduino platform and code. Maybe the challenge could include the delivery a payload, a speed test, the navigation of an obstacle course, endurance flight? Although there are a few such builds on YT, it would be interesting to see Jame's approach having enjoyed his builds to date.
The cycloidal drive gets it's name from the shape of the gear teeth, a cycloid. One of the big perks of this type of gear is that there is pure rolling contact between gears of this type, rather than the sliding that occurs with involute gears. This means that those outer ring bearings should be redundant, and the fact they are turning is a sign the tooth profile is not correct. Glad to see you considering these though, maybe also look at 3D print+belt "strain wave gears", I don't personally like them because they work by fudging some of the tolerances and clearances more than the more industrial version but they seem to work. Also, you can "invert" the drive and have the outer gear as the output, if you stationary fix those pins that go through the inner cycloidal gear.
Really? I thought it was the opposite, that involute gear teeth have theoretically perfect rolling contact, and cycloidals always have some amount of sliding. How are you generating your cycloidal curves? I've been using these equations, but I'm not sure how to analyze the exact amount of sliding that happens and/or whether there's an ideal pin radius to minimize it. x = R * cos(t) + e * cos(N * t) y = R * sin(t) + e * sin(N * t) Then inset by pin radius R = ring radius N = number of pins e = eccentricity t = 0...2pi
@@dekutree64 It's been a while but I wrote an openscad script to generate cycloidal gears. Essentially you are tracking a point on the circumference of a circle as it rolls on another circle. But it's the other way around, cycloidal gears have pure rolling contact and a variable pressure angle (goes from 90 to 0 if memory serves) which is what makes them bad for power transmission, but good for low friction and wear, so they are sometimes used in mechanical watches. Involute gears have a constant pressure angle, which makes them good for power transmission but there is sliding contact. en.wikipedia.org/wiki/Involute_gear There is rolling contact, but only for the instant where the line of action crosses the line connecting the two gear axles. involute.pro/fileman/Uploads/sliding%20velocity.pdf this also describes it in more detail
@@H34... But does generating the curve by rolling a circle mean that you have rolling contact against stationary pins as in a cycloidal drive? Seems like the pins would need to roll like the circle that you generated the curve from. i.e. the perimeter length of each disc tooth is equal to the pin circumference, so in a theoretically perfect machine where the disc maintains constant contact with all pins at all times, the pins would make one revolution for each turn of the input shaft/advance of one disc tooth. In a real machine the disc is only in contact with ~1/3 of the pins at any given time, but they should still be rolling at the same angular velocity as the input shaft during that time... unless I'm failing to visualize it properly (which is possible)
@@dekutree64 yes, you have rolling contact against a stationary pin. Imagine a fixed pin, and a pipe (loosely) sleeved over it, you can roll the pipe around the pin without sliding them against each othef and it sort of orbits and rotates, which is exactly what cycloidal drives do.
@@H34... Hmm, I guess the problem with my mental simulation was that when rolling the cylinder to create the curve, the disc is stationary, whereas in the working machine the movement of the disc is equivalent to rolling the pins in the opposite direction. So then are the roller pins in some professionally made cycloidals just to reduce cost by allowing for lower precision machining of the discs, and to compensate for other sources of imperfection such as deformation under load, thermal expansion, wear over time, etc.? Thanks for the help! I'll have to compare the curve generated by those equations I posted to one generated by cylinder rolling and see if there's any difference.
Looks like the cam sheared at the layer lines. A high stress part like that might need to be printed at 100% infill and remelted in salt to get uniform shear tolerance.
Version 2 of my Cycloidal Drive is coming up in a couple of weeks!
hype is real
Genuinely really looking forward to it James, I love videos like this where you're experimenting and innovating with robotics.
Crazy thing :) you are amazing ! Have you seen this guy robot arm with cycloidal motor th-cam.com/video/4IfH93HYcpo/w-d-xo.html
Why not a "normal" planetary gear?
Great
This is becoming increasingly challenging to follow. I like it VERY much.
Strange, I am following along perfectly. Though I do have problems following along with all the jargon for code, and coding programs. This is a breath of fresh air for me, compared to the other videos.
I started out in the computer industry as a field service engineer in 1970 and some of the mechanical contraptions around then were unbelievable, I found electronics much easier to follow.
Here we are over 50 years later and I'm still discovering these amazing mechanical devices.
If you optimize your teeth design you can make it contact 100% around the cycloidal disc, that's where the real benefits are with this type of drive
correct, I see no reason why this should not work more perfect with real gear tooth design instead of these round teeth. But certainly much more efforts. I have seen this only once. All other designers do it as you do (with the half circles as teeth)
I’d like to to point out that this is not an actual cycloidal transmission, even the animation doesn’t not show it correctly. The cycloidal disc has a specific shape to it which can’t be designed with a basic cad sketch - nonlinear. It has to be calculated and interpolated (e.g. matlab to dxf to cad). I built a full metal version for a robot link myself (video..), there is no room for shape imperfections :) The actual shape will improve output speed consistency, load distribution around the circumference. In addition: Multiple disc will help to reduce load induced eccentricity and vibration..improve the efficiency (back drivability). As a hint: every roller has contact to the cycloidal disc at any position in rotation. Might seem difficult, it can be described - for “each“ position - by means of ruler and compasses though
Aforementioned video link th-cam.com/video/pzTwEX9iBq4/w-d-xo.html
Is there a technical name for this type of 'cycloidal' variant, or is it just a bastardized version that only works if the materials are somewhat compliant or have large tolerances?
@@rdyer8764 I‘m not aware of a suiting name. It somehow appears as a cycloidal without being a cycloidal :) The cycloidal itself defines a specific shape that’s created by rolling one shape in relation to an other one and tracking a point one the moving element- e.g. circle over circle or circle over a straight line.
@@antitriangular2828 That's pretty damn cool! I think that equation gave me a mathgasm! I love seeing stuff from people way smarter than I.
@@rdyer8764 Hah. Unlikey, I just happened to have been working on an anti-backlash variant of Paul Gould's work after printing his version last week.
In fact, Paul Gould includes his inventor files and the equation is embedded in the defining profile for the disks. I ended up looking up and re-doing it myself because I don't like using equations I don't understand (also - I couldn't get the ratios I wanted to work correctly, and wanted to understand why!).
Im glad to see you working on the robot dog again
I am in my 30s with absolutely no engineering background and yet I've somehow stumbled into Gear TH-cam and I can't stop watching
Yes yes yes, i love seeing These cycloidal bois popping up all over TH-cam. I am currently working on an actuator where i integrated a 16:1 cycloidal gearbox into the stator bore of a 8108 BLDC motor to make it super compact.
excellent project 👌😎 very curious about V 2
Yes it is , ... *** family guy characters staring in your eyes ***
th-cam.com/video/tgEOpl880KM/w-d-xo.html for V 2
This has got to be one of the best example of a 3D printed cycloidal drive already. definitely excited for two cycloidal discs and more bearings!
Thanks, it's coming up in 2 weeks
I don't know if I can hear it because of having young ears, but I love the high pitched sound that the motor makes when you were initially testing it - very cool.
I can definitely hear it, and it sounds awesome. If you can hear the high-pitched whine of a CRT TV, you can hear this.
the shift going from the small inner gear to the 10-leaf-clover was very easy to follow. well done mate
A cleverly designed 2 stage belt system can be very compact and strong. The trick is to use a very small difference in cog diameter, have the second stage coaxial with the first stage, and then spin the casing that holds the cogs. So the casing becomes the input shaft, one of the cog shafts becomes the casing, and the other (coaxial) cog shaft becomes the output shaft.
I recently experimented with cycloidal drives myself because I find the principle really fascinating. I didn't do it with such a high-torque or clean design but here's two interesting things I discovered:
If you use a correctly calculated cycloidal shape with well-tuned tolerances you can *drastically* reduce the eccentricity(wobbling movement). This not only reduces the strain on the motor and other parts, it also allows for more compact designs as - like you showed in the video - the holes for transmitting the movement from the gear to the output shaft depend heavily on the eccentricity. The drawback of this is of course that tolerances become more significant.
The second thing is probably not as relevant for your project because it's more suited for high gear ratios and hurts the ability to backdrive the mechanism, but double-staged cycloidal drives can be simpler to print and build as the output is automatically a non-wobbling rotation without the need of this transmission via holes in the cycloidal disk. So it can again be made smaller. I combined those two aspects to print a tiny double-stage gear with a ~1:1000 reduction, with an eccentricity of just 0.6mm! It's not very practical but it was more of a quick feasability experiment and a lot of fun to make, and interestingly works more smoothly than my failed first try using a single stage.
Absolutely fantastic engineering. This is the kind of video that inspires people to learn... well everything, physics, math, statics, dynamics. It's amazing what youtube brings to the world through intelligent creators like you.
I especially liked this video, James! The way you walked through the problem, iteratively introducing each part of the solution was very informative and satisfying.
Been watching Paul for months. Fantastic upgrade
The best revolution in James Videos!
I see what you did, there. It's a joke.
Hey, I did a version of a Cycloidal Gearbox with all printing files available and a Fusion 360 script which lets you create the reduction ratio on the fly... it is backdrivable!
I am a big fan of Cycloidal Drives! Keep it up!! 😀
I was a vibration analyst in a previous life and these things are my worst enemies.
Thats nothing xD
I saw CNC-machines that shook the building they stood in because they accilerated and stoped so fast^^
The building was checked regulary to withstand it but it was crazy. They once tested a machine not bolted to the floor and it moved like an arms length in a few minutes.
@@benjamin4321 veritasium has a video or two on vibrations
@@JL-pc2eh Your run of the mill Haas has to be anchored to the concrete beneath because the rapids produce enough inertia to rock the machine when it comes to a stop. It is one of their huge downsides. Higher quality machines built with larger and heavier frames don't suffer from the same rigidity issues. Even if the Haas is anchored, the vibration from the lack of dampening will translate into surface finish issues on the part being machined.
industrially they are built with multiple stages out of phase to counteract the imbalances, which he mention around 10:50
@@samrevers742 Found it. th-cam.com/video/rEoc0YoALt0/w-d-xo.html
It was Steve Mould
I got interested in these Cycloidal drives to use for a self built CNC lathe for the C-axis. It would have to be clutched to the spindle when activating C-axis. I think you could use the same motor for normal spindle drive (high speed) and mechanically shift to C axis mode (high rigidity, low speed positional control). The reason to use a cycloidal gear is that it has almost no backlash and you can get very high reduction and rigidity (if made from something like steel, not PLA, and with tight tolerances).
The point is however, on a lathe you often want a through spindle bore. The cycloidal gear would need to have a hole in the middle and I think I have found a way how to do it. Take a look at the output shafts. They basically are excenters aswell, so you could lose the excenter in the middle. Also those output shafts (that are the input as well) don't have to be inside of the cycloidal disc itself, but imagine a disc that does the exentric wiggly thingy (not actually rotating) and the cycloidal disc is "glued" onto it. Then the outer case actually becomes the driven output.
Just some ideas. First idea works well in CAD, second one I'll have to dive in to and do some designing.
Cycloidal drive is basically a lob sided subset of planetary gear drive method. Planetary gear set so much stronger, balanced, tighter, efficient and reversible.
I knew you would get to cycloidal drives eventually. Amazing work.
It's time people switched to bearings pressed onto dowel pins. They're mass-produced precision parts, and all they need is a reamed hole in the plastic parts to receive them for repeatable interference fit
CNC mill a version of it out of metal when you have a model that works like you want and use that to make it both smaller and more solid. Epic cycloidal gear by the way :D
I came here to tell him that too. I love my 3d printer but there's only so much its capable of. Gears not really one of them for this.
@@santosvella he want to make his robot 3D printables.
@@santosvella It's good if you want to do testing. One you have something that works, then you go for the milled metal parts. If that works or not, you tweak it, rinse repeat and soon you have your working device or prototype.
@@taleg1 Yup, that's what i use my 3d printer for. Wish i had a cnc though.
@@santosvella Maybe one day soon we'll get new 3D printers that are able to do multi materials that include ceramics and metals. I know we can do that now with some really expensive gear, but imagine what we could try with 3D printers that could created items of durability.
I saw this demo of a very very custom and very advanced 3D printer being researched that more or less could do any material. It could even do 3D milling. It was insane and the cost was in the millions. But we'll get there one day.
That's really neat! I'd never even heard of a gearbox like this, I just thought it was going to be a planetary gearbox. Thank you for introducing me to a different type of drive that can be 3d printed, and looks so interesting when it's running!
thats by far the best 3d printed one I've seen!
super cool stuff, you are a master of design
Since I recently got a 3d printer, I now fully realize just how much you are able to get done on one within a week. A lot of my prints have averaged at 24 hrs per print. But even with smaller prints, they take longer than I thought. You have several printers now to help you get more done, but even with 1 printer, you seemed to work fast.
Try 1mm nozzle and either .25mm or .4mm layer height, 45mm/s, 210-220C for PLA. Thinner layers allow steeper unsupported overhangs. Supports can add a lot of print time and material use, so design to minimize them. If you have something high up on a model that needs support, see if you can build one in that angles up at 45 degrees from a nearby surface. Much more efficient than a tower all the way from the build plate.
Hi James, you can totally get to 10:1 reduction if you use a pulley force multiplier. Essentially if you replace a big pulley with a large bearing fix one end of the belt back on the body while putting an idler on the leg so that for 2 times the movement of the belt you will have 1 time the travel of the leg.
Mounting the bearings on shoulder screws instead of bolt threads works nicely.
Properly shaped gear teeth would probably help too.
Really interesting video as always James
Pretty cool to see one of these built dogs home built.
that's really cool. like 3d printed version of a mazda rotary engine in reverse, and rotary engines stack together with offset crankshaft too.
Loved this. Looking forward to v2.
That's going to be an unending joy, once your accellerometers get a load of 4 or more of these gearboxes.
Version 2 comes up in a couple of weeks with 2 discs in
James, You Boggle my Mind more and more with every Video you Post... Your a Modern Day Genius to the power of 10 !!!!
What a really neat design!
For a similar result, but with everything running perfectly "round" have a look at "Split-Ring Epicyclic Gear" (or "differential epicyclic gearset", "compound-planet epicyclic", lots of names for the same device). It is also back-drivable (but there is more friction).
You might also consider the "Strain wave gearing" that is also compact, has massive reduction-ration and no backlash (and is supposed to be back-drivable, even if this doesn't seem obvious) ; it is 3D printable but requires one "gear" to be printed with TPU or equivalent, because is relies on deformation to transmit the motion.
Such a very elegant design you made, Bravo !
Awesome! Im so impressed it’s back-drivable
Consider, bearings without sealing with less friction probably better suited for this project. Great job!
Fantastic video! This is a brilliant explanation of both the function of a cycloidal drive AND your thorough design and iteration process. Really like it - looking forward to seeing v2!!
Super cool! I've been trying to make my own cyclodial drive for a tiny jumping robot for a while now.
2:16 you quoted stratus productions as that video source which is technically correct as that’s the url, but the channel name is rctestflight
what he said
Yip I was confused. Had no idea that was his channel url as the video links are always shortened th-cam.com/video/QVep9iSXVeo/w-d-xo.html
Weird, I was sure for second he was crediting a freebooted version of the video. The more you know
Insert another rotor (yellow) on offseted 180degree bearing on the motor shaft this will neutralise most off the vibrations
Fantastic product excellent staying power i am in awe!!
I can not express my happiness and relieve when I looked right and saw "Cycloidal Drive V2"
There's also a better testing video that was published a couple of weeks later.
You can use M3 of M4 bolts of 12.9 steel quality instead of M6 overkill bolts. Smaller bearings would also allow you to make the device much smaller and lighter for a better impulse response. Looking forward to see it in action!
All the bolts are M4
The best version I've seen so far!
Im no engineer James but I am a mechanic and we use molybdenum disulfide grease for CV shafts, diff installs and I rebuild my old tools and use it on the sintered gears. My theory is because of the nature of that shit, moly grease should be perfect for a 3d printed gearbox if you use hard-wearing plastics because it'll soak up into the print lines and it sort of embeds the gears with a harder metal so they last longer. I don't understand this as I say I am a humble mechanic and I know near to nothing about 3d printing but I hope that this may help in future.
Love Owen.
I absolutely loved this! Your channel inspired me to study engineering and this video really reminded me why I made that decision. Thank you!
Wow you're on another level, amazing well done.
I love this design!
Since you're sticking the shaft through the center with a cam
To stop the vibrations you could mount a weight on the shaft that matches the weight of the gear and stick it 180⁰ out of phase. That way you don need a crank that has to go through two gears. Though getting them balanced perfectly would be difficult. (but you do have the sauce for that in the current design due to the cutout hole)
Way of explanation is high level sir
Make the cam shaft out of metal. Instead of a straight pole off center, make a centered pole with a kink. This will also make it simpler to secure on the other end. The craftsmanship is good enough as is for the rest to hold up to higher torque.
the quality of these videos is astonishing.
I am so glad you are designing and testing these types of gears. Dare I say you are putting the ole Bruton spin on it (pun intended). Looking forward to next version!!
Great design
Thanks for sharing your experience😀👍
I thought that cycloidal gear reductions couldn't be back-driven, but I was reaching that conclusion based on OskarPuzzle's "11 million to one gearing". It's nice to be able to update my mental models.
That’s pretty damn impressive sir.
If you use prime numbers of teeth for the gears you can get the teeth to wear out more evenly.
Glad I came here looking for potentially useful comments
For measuring torque you can get those spring weight measuring tools and hook it to the handel at 90° and then lett it run you'll get the torque.
Wonderful stuff! You got me hooked with the balance gyro ;D
This seems very promising. Good job
James, I am just sharing my input, take it as my opinion and nothing else, You know I have been following your channel for a very very very long time, this video and last few for that matter, the way you have been producing (and or scripting) them, they are sounding more and and more like a Tom Stanton video's, There is nothing wrong with Tom's videos he has his own thing going on, he is just not everyone cup of tea, you have almost 1M subscribers because of your energetic energy and your brilliant approach to accomplish the project at hand, which was reflected in the way you made your video's, that is why we are all still subscribed to you, you are so close to the 1M, now is no time for to change. I and the many thousands of us, that have been subscribers before you had even 100k subs, all want to see you hit that Millon sub.
Hey, yep trying to find a balance (but also fix the low view counts ;-)
@@jamesbruton It is none of my business to suggest anything, as you have already surpassed our expectations and then some, James, you have shown us years ago how brilliant, you and your approach is, you have nothing to prove to us, we already know all that about you. I do understand your point, So perhaps the answer you seek is in the past, as of late, your average view count per upload, has been somewhere between 50k to 90k some a little more some a little less, however, go back 2 or 3 years it is more like 90k to 200 plus k, Perhaps it's not your "balance" but the projects? don't forget most of us AKA the loyal subscribers that have been around for the last 7 or 8 years, are old dogs, we need to be stimulated with diversity loll Take Collin, for example, none of his video's features the same project more than one or two video's, sure he will go back and revisit them now and again. IDK Perhaps bring back that Arty hottie maker friend of yours, on videos more often, mix it up a bit, nothing brings views like a hot maker chick as an assistant haha. JS, James, your videos will always get a like from me.
Excellent work! A counterweight on the offset drive shaft would reduce the vibration.
Nice job James! I love watching your robot videos.
You can push the output pin on brushless motors through the body, to convert them to work inboard rather than outboard.
I look forward to seeing version 2. I certainly think once you sort out some of the bugs and create a good design it will work well for lots of your projects.
Epic levels of under extrusion on those prints dude
You previously had issues with the motors in Opendog 2 heating the plastic, so you fitted those metal plates to dissipate the heat. Might be worth doing similar again.
Probably, although this is 10:1 and the belts were 5:1, so I get the same torque for half the power/heat.
Magnets instead of bearings. No friction=no wear. Great video!👍
It also has the bonus of sounding cool as hell, come on, I saw this video and thought you were going to be making a spacecraft haha
This was very informative. It helped me with the exams. Thanks!
Does strike me that the design can be very easily machined on a cnc machine. Great work, thanks. Looking forward to V2.
Really cool project and your explanation (step by step) is 10/10 !!!!!
Just one recommendation. Throw this 3D printer in the thrash and get a cheap Creality Ender 3, you won't believe how much better it is :)
1:21 - those headless cricket dogs are terrifying
This is so cool! I've been thinking that cycloidal drives would be perfect for OpenDog for a while, but I always figured either there was some missing feature or you'd get around to them eventually. I'm really excited to see V2!
this is what I call a great youtuber
This japanese invention used in Hajabusa blanes. Usually has two inner teeth in 180° ankle from each other to reduce resonance, and tear when there is allways atleast 2 inner teeth touching outer teeths in opposite sides. The durablity is better.
You have a cnc router, why not use that and cut all the parts in aluminium
Even might be smaller than 3D printed
I really want to make it accessible. If I can make it 3Dprinted, then I can always upgrade later.
@@jamesbruton this is patent worthy
@@atharvbhalerao3062 No Cycloidal Drive have been in use for a weary long time. Nothing novel here.
@@jamesbruton I'm really thankful for that!
This would make a good bed shaker alarm. I'd buy one.
awesome design . it looks like the clutch on an atv or motorcycle. lol
While the cycloidal drive option is a really nice one, I'm personally not convinced that you couldn't reach the same goal with a planetary gear set. Regardless though.. I love the solution :)
Awesome video. Excited for the next episode! Subbed
Think this could use some M10 smooth rod:
- Ditch the exterior bearings and run the rotor directly up against the rod. Rotot on steel + silicone lube should be fairly low friction
- Same for the bearings inside the rotor: just put small smooth rods through each hole
- Finally, even the centre axle could be replaced. Then add a 3D printed cam and drill a fixing bolt through the rod
= smaller, fewer parts by ditching all the bearings and easy enough to build if you have a rotary tool with a cutting disc
This is an absolutely brilliant job. Well done 👍
Very interesting video, well edited. Thanks for that
This is fantastic, I’m very curious at how well it will do
You could save a lot of space by replacing the ball bearings on the ring and the output disc with plain bearings (aka bushings) running on smooth steel shafts. They can be 3d printed from nylon or graphite filled pla. Obviously this arrangement will have a shorter service life and more friction but the cost, size and weight savings may outweigh that, especially since well designed plastic plain bearings actually last a really long time.
Amazing work as always!
I'd be interested to see James design and build his own version of a 3D printed quadcopter based on the Arduino platform and code.
Maybe the challenge could include the delivery a payload, a speed test, the navigation of an obstacle course, endurance flight?
Although there are a few such builds on YT, it would be interesting to see Jame's approach having enjoyed his builds to date.
i subed and liked just because this video made my day and was super wholesome
Thanks, V2 is coming up in a couple of weeks.
Me too!
This is very nice!! Great job!!
The cycloidal drive gets it's name from the shape of the gear teeth, a cycloid. One of the big perks of this type of gear is that there is pure rolling contact between gears of this type, rather than the sliding that occurs with involute gears. This means that those outer ring bearings should be redundant, and the fact they are turning is a sign the tooth profile is not correct.
Glad to see you considering these though, maybe also look at 3D print+belt "strain wave gears", I don't personally like them because they work by fudging some of the tolerances and clearances more than the more industrial version but they seem to work.
Also, you can "invert" the drive and have the outer gear as the output, if you stationary fix those pins that go through the inner cycloidal gear.
Really? I thought it was the opposite, that involute gear teeth have theoretically perfect rolling contact, and cycloidals always have some amount of sliding. How are you generating your cycloidal curves? I've been using these equations, but I'm not sure how to analyze the exact amount of sliding that happens and/or whether there's an ideal pin radius to minimize it.
x = R * cos(t) + e * cos(N * t)
y = R * sin(t) + e * sin(N * t)
Then inset by pin radius
R = ring radius
N = number of pins
e = eccentricity
t = 0...2pi
@@dekutree64 It's been a while but I wrote an openscad script to generate cycloidal gears. Essentially you are tracking a point on the circumference of a circle as it rolls on another circle.
But it's the other way around, cycloidal gears have pure rolling contact and a variable pressure angle (goes from 90 to 0 if memory serves) which is what makes them bad for power transmission, but good for low friction and wear, so they are sometimes used in mechanical watches.
Involute gears have a constant pressure angle, which makes them good for power transmission but there is sliding contact. en.wikipedia.org/wiki/Involute_gear
There is rolling contact, but only for the instant where the line of action crosses the line connecting the two gear axles.
involute.pro/fileman/Uploads/sliding%20velocity.pdf
this also describes it in more detail
@@H34... But does generating the curve by rolling a circle mean that you have rolling contact against stationary pins as in a cycloidal drive? Seems like the pins would need to roll like the circle that you generated the curve from. i.e. the perimeter length of each disc tooth is equal to the pin circumference, so in a theoretically perfect machine where the disc maintains constant contact with all pins at all times, the pins would make one revolution for each turn of the input shaft/advance of one disc tooth. In a real machine the disc is only in contact with ~1/3 of the pins at any given time, but they should still be rolling at the same angular velocity as the input shaft during that time... unless I'm failing to visualize it properly (which is possible)
@@dekutree64 yes, you have rolling contact against a stationary pin. Imagine a fixed pin, and a pipe (loosely) sleeved over it, you can roll the pipe around the pin without sliding them against each othef and it sort of orbits and rotates, which is exactly what cycloidal drives do.
@@H34... Hmm, I guess the problem with my mental simulation was that when rolling the cylinder to create the curve, the disc is stationary, whereas in the working machine the movement of the disc is equivalent to rolling the pins in the opposite direction.
So then are the roller pins in some professionally made cycloidals just to reduce cost by allowing for lower precision machining of the discs, and to compensate for other sources of imperfection such as deformation under load, thermal expansion, wear over time, etc.?
Thanks for the help! I'll have to compare the curve generated by those equations I posted to one generated by cylinder rolling and see if there's any difference.
Looks like the cam sheared at the layer lines. A high stress part like that might need to be printed at 100% infill and remelted in salt to get uniform shear tolerance.
Hey man great content really well explained all throughout. Also loved the modelling you did for the wallet ;) take care
@James Bruton
Hi fellow engineer. I just came across your channel and really enjoy what you are doing. Subscribed!
I look forward to your next video
Thanks, the next one on this is scheduled for Tuesday 30th