Very clever mechanism, and a very educational video. The principle of the bend axes of the flexures intersecting at a common point feels like a very general principle that I can apply in my own flexure designs. Thanks! (I especially appreciate you providing the STL files for the mechanisms you create.) (Would it also be possible for you to post the CAD files themselves, so we can play with them or incorporate elements in our own designs? F360 would be preferable for us hobbyists, although I suspect you use Solidworks yourself…)
I am unsure exactly what it is about compliant mechanisms that make me angry. I realize they are a good idea. They're elegant and I see the benefits. I think it's because I feel like we've spent a long time as a species fussing over joints and parts and oiling the points where things connect and this and that and the other thing.... when we could have just been like "oh, bendy thing no break herp derp"
They aren't equivalent, a proper spherical joint is very rigid and can take significant loads. Flexures like this have very limited rigidity, it would be easy to move the sphere away from the centre of rotation with little force. Much more useful for applications with negligible loading where a part cannot be mechanically constrained.
How do those flex modules prevent up/down movement? And if they can't do that, then it isn't going to be able to keep the small sphere in a single location.
They can do that - each blade is very stiff in the width axis compared to the flat axis. With the flexures bent along an angle like they are, it means that any translation of the center point of each flexure will be accompanied by the blades' stiffness effecting a rotation in the center point as well. You can overcome that if you can overcome the strength of the blade flexures, but the point of the device is it's just easier to move individual flexures while inducing that ideal rotation around the centerpoint than not to. Combine multiple flexures together and you end up with a device that's pretty well constrained in translation but very poorly constrained in rotation.
@@predragbalorda It does look like it would be quite a challenge to get it small enough to have the same packaging efficientcy. You might just end up with a lot of very small precision parts to replace what is essentially just a ball, which can be turned out rapidly on a cnc lathe.
@@PartykongenBaddi 3 parts to be exact. Also a ball requires lubrication due to friction between mating surfaces and the ball(s). This thing has no moving parts ergo lasts forever (or untill material fatigues enough to break). There is a reason they use flexures on the JWST. Don't get me wrong I get your point but different requirements for different usage scenarios - minimal servicing means flexures.
@@predragbalorda i was just thinking of how small this would be to replace a bearing with 14mm outer diameter as some of the spherical bearings we use in small car suspension are. Those are also maintenance and lubrication free by use of teflon composite bearings.
Based on the geometric explanation of this specific setup, I would guess it is analogous to the static index of refraction in most manufactured products. Sure you could possibly have a continuous solution … but it might be significantly more complex to fabricate (in terms of the technique) or necessitate tighter tolerances.
Yes. And actually 1 would be enough although it wouldn't be symmetric. Two would be symmetric and may be best for practical application. We picked four to do the cool interlocking design and to be able to hold up the weight of the heavy dome. This piece was more of an artistic sculpture than a practical machine
The blue triangle bits have all of their faces oriented to pass through the center, and with all of those creases each face can only move/flex in sphere-tangential directions. None can move radially towards or away from the center. (Judging from the video the center tip does appear to jiggle slightly.)
@@jacobolus Thanks. And yet, that's an awful lot of material: a small flex along each joint in that path could represent a fairly large overall deflection. I'd be curious to see a stress/strain plot for translation.
You made a nice video and it demonstrate well what you wanted to show. But the construction is heavily over constraint. Which is sad because if the principals of flexure design would have been followed, it would have been well designed.
Haven't anybody noticed that its not holding the position of that sphere in the same spot all the time? It's not much but that is visible on the video so it must be couple of millimeters so not enough to get this doing any useful work I think
Very much depends on what 'useful work' is here. As shown, it won't give submillimetric precision - but there are a lot of areas where that is absolutely sufficient, especially when combined with the other advantages of compliant mechanisms. Also, it depends on what materials you use. PLA will flex in ways that e.g. spring steel will not.
@@Barnaclebeard I can't really agree with that. Flexures are all about removing any lost motion and reducing or eliminating friction- those are key attributes in 'precision applications' I've known them in classical precision Instrument design, not much in power transmission.
I was wondering if this could be adapted for use in an astronomical mirror mount whiffle tree. You want to have each contact point on the back of the mirror not introduce stress via friction/stiction, but allow some lateral movement and no vertical displacement.
@@autochton This is a good suggestion but I can't fully agree cause what I see here is rather few millimeters than submilimeter. There are obviously some applications that this would be enough but at the same time lots of limited ones
You probably saw this already, but just in case: ua-cam.com/video/HXB925ptd7Y/v-deo.html&lc=UgyuoV7ubEDfYNtLvP94AaABAg.9aP8Lj2ct0G9aPZbb6xlTO "Yes. And actually 1 would be enough although it wouldn't be symmetric. Two would be symmetric and may be best for practical application. We picked four to do the cool interlocking design and to be able to hold up the weight of the heavy dome. This piece was more of an artistic sculpture than a practical machine"
So that was really interesting the second time I watched it, the first time I was waiting for you to call it prefamulated amulight.
First time I thought it was a demonstration of how side fumbling is effectively prevented in the waneshaft.
For a moment there the narrator almost sounded like the “Turbo Encabulator” guy lol. Excellent presentation nonetheless.
Ooooooh that's my statics professor! Awesome!
He looks more dynamic than static.
Thank you for explaining the converging geometry of the flexure.
that is really cool! would be interesting in coupling it with an actuator
This make my brain compliant
Flexures are so interesting. Thanks for sharing this. I'm printing another model I found on this channel right now.
I remember printing one of those modules - super cool.
This should also work with 3 instead of 4 flexture modules, right?
Yes and two. Three is awkward because then they don't interlock. I did four to hold it up and get a cool interlocking look
I literally thought it was a computer simulation at first. Thats cool!
Very clever mechanism, and a very educational video. The principle of the bend axes of the flexures intersecting at a common point feels like a very general principle that I can apply in my own flexure designs. Thanks! (I especially appreciate you providing the STL files for the mechanisms you create.)
(Would it also be possible for you to post the CAD files themselves, so we can play with them or incorporate elements in our own designs? F360 would be preferable for us hobbyists, although I suspect you use Solidworks yourself…)
Super cool! I printed this but the Base_1_V3.STL file is empty, can you please repost.
excellent! as usual... my sincere respect. following you.
What about fatigue fractures? How do compliant mechanisms deal with it?
That is so awesome! It reminds me of a hip ball joint. I want to 3D print this over the summer. Can the thinigiverse link be fixed?
Awesome tech. Thingiverse link is broken though
Yeah that is right... what gives?
I am unsure exactly what it is about compliant mechanisms that make me angry. I realize they are a good idea. They're elegant and I see the benefits. I think it's because I feel like we've spent a long time as a species fussing over joints and parts and oiling the points where things connect and this and that and the other thing.... when we could have just been like "oh, bendy thing no break herp derp"
They aren't equivalent, a proper spherical joint is very rigid and can take significant loads. Flexures like this have very limited rigidity, it would be easy to move the sphere away from the centre of rotation with little force. Much more useful for applications with negligible loading where a part cannot be mechanically constrained.
How do those flex modules prevent up/down movement? And if they can't do that, then it isn't going to be able to keep the small sphere in a single location.
They can do that - each blade is very stiff in the width axis compared to the flat axis. With the flexures bent along an angle like they are, it means that any translation of the center point of each flexure will be accompanied by the blades' stiffness effecting a rotation in the center point as well. You can overcome that if you can overcome the strength of the blade flexures, but the point of the device is it's just easier to move individual flexures while inducing that ideal rotation around the centerpoint than not to. Combine multiple flexures together and you end up with a device that's pretty well constrained in translation but very poorly constrained in rotation.
This is quite an ingenious mechanism! Does it have any known or plausible applications?
Aiming of gamma ray beams for treatment of cancers.
Ball joint on wishbones of a car which lasts forever
@@predragbalorda It does look like it would be quite a challenge to get it small enough to have the same packaging efficientcy. You might just end up with a lot of very small precision parts to replace what is essentially just a ball, which can be turned out rapidly on a cnc lathe.
@@PartykongenBaddi 3 parts to be exact. Also a ball requires lubrication due to friction between mating surfaces and the ball(s). This thing has no moving parts ergo lasts forever (or untill material fatigues enough to break). There is a reason they use flexures on the JWST.
Don't get me wrong I get your point but different requirements for different usage scenarios - minimal servicing means flexures.
@@predragbalorda i was just thinking of how small this would be to replace a bearing with 14mm outer diameter as some of the spherical bearings we use in small car suspension are. Those are also maintenance and lubrication free by use of teflon composite bearings.
Is there any video on flexure U join designs? I’m trying to make 3d printed 2dof load cell
Bobble heads will never be the same.
Damn, the thingiverse link is 404'ing. Did anyone get the files?
No!!
Sick!
how could or would you mechanically control these though?
Why do so many of these flexure based mechanisms use a combination of straight blades and sharp corners instead of curves?
Based on the geometric explanation of this specific setup, I would guess it is analogous to the static index of refraction in most manufactured products.
Sure you could possibly have a continuous solution … but it might be significantly more complex to fabricate (in terms of the technique) or necessitate tighter tolerances.
All that time and effort building Airfix kits when I could have just used an animated sequence to put them together. 😂
Hypothetically, is it possible to use this design for the manufacture of a seismic sensor?
Lisää vain metallipallo ja Hall-ilmiövirta-anturi
In this example they used four fexures. But wouldent three already be enough?
Yes. And actually 1 would be enough although it wouldn't be symmetric. Two would be symmetric and may be best for practical application. We picked four to do the cool interlocking design and to be able to hold up the weight of the heavy dome. This piece was more of an artistic sculpture than a practical machine
The chroma keying used seems really off for some reason.
Very cool, but its not perfect there is too much slop you can see the ball is displacing on Z and X axis when moved.
Not seeing how this prevents translation along the x, y, or z axes--which would push the probe tip out of alignment
The blue triangle bits have all of their faces oriented to pass through the center, and with all of those creases each face can only move/flex in sphere-tangential directions. None can move radially towards or away from the center. (Judging from the video the center tip does appear to jiggle slightly.)
@@jacobolus Thanks. And yet, that's an awful lot of material: a small flex along each joint in that path could represent a fairly large overall deflection. I'd be curious to see a stress/strain plot for translation.
Enhanced bobble head
N64 controllers sticks would never wear out
You made a nice video and it demonstrate well what you wanted to show. But the construction is heavily over constraint. Which is sad because if the principals of flexure design would have been followed, it would have been well designed.
Were printed on various prusa printers "shows an ultimaker" 😅
Haven't anybody noticed that its not holding the position of that sphere in the same spot all the time? It's not much but that is visible on the video so it must be couple of millimeters so not enough to get this doing any useful work I think
It's a flexture. It's not for precision.
Very much depends on what 'useful work' is here. As shown, it won't give submillimetric precision - but there are a lot of areas where that is absolutely sufficient, especially when combined with the other advantages of compliant mechanisms.
Also, it depends on what materials you use. PLA will flex in ways that e.g. spring steel will not.
@@Barnaclebeard I can't really agree with that. Flexures are all about removing any lost motion and reducing or eliminating friction- those are key attributes in 'precision applications' I've known them in classical precision Instrument design, not much in power transmission.
I was wondering if this could be adapted for use in an astronomical mirror mount whiffle tree. You want to have each contact point on the back of the mirror not introduce stress via friction/stiction, but allow some lateral movement and no vertical displacement.
@@autochton This is a good suggestion but I can't fully agree cause what I see here is rather few millimeters than submilimeter. There are obviously some applications that this would be enough but at the same time lots of limited ones
4 springs to restrict 3-DoF - - isn't this overconstrained?
..1:27 looks like an Ultimaker ;) not Prusa..
You probably saw this already, but just in case: ua-cam.com/video/HXB925ptd7Y/v-deo.html&lc=UgyuoV7ubEDfYNtLvP94AaABAg.9aP8Lj2ct0G9aPZbb6xlTO
"Yes. And actually 1 would be enough although it wouldn't be symmetric. Two would be symmetric and may be best for practical application. We picked four to do the cool interlocking design and to be able to hold up the weight of the heavy dome. This piece was more of an artistic sculpture than a practical machine"
three-dimensional spatial space none inertia gyroscope .
.
gay