You could have a sprung tensioner on only the top of the flat sections that tensions by pressing the track upwards to compensate for the removal of the bottom tensioner for a flat driving surface.
Unless you have something bringing the track back down, wouldn't that encourage the belt to come off? I'm talking specifically about when bending the track.
Spring load the idler wheel inline with movement. You'd probably need some thicker rods to constrain the movement direction. the lateral constraing at the hinge should be ok to take the moment and not force the track sideways??
Use elastics between the links to tension the belt so that way it will be tight on both the inside and outside of the turn. Love your work its amazing. =)
My thoughts would be to introduce a resilient spacer into the slot that the pin rides in - to provide resistance that pulls the pins back to their rest point. This would allow you to effectively tension the track without just using up all the pin travel in the process. If you can get this to work, it would be perfect for making a tracked bicycle!
@@TheMagman Are you sure that's the name of whatever vehicle you're thinking about? I can't seem to find it. Edit: Nevermind, I found some clips that had it, though I still can't find a single piece of information about the actual vehicle.
The tensioning mechanism definitely needs to be *inside* the track. My immediate thought is a spring arrangement between the open end of the center pivot and the idler's frame; alternatively, make the idler itself able to ride in and out along its frame. Either way, cool start, neat idea, looking forward to version 2.
You could add a "roof" to the side walls the tracks currently have, that would keep the track fixed to the bearings. I wonder if adding a second bend axis sort of like an inchworm where it can bend the mid section up/down as well as left/right might help with obstacle climbing.
With a single articulation, I'm not sure if bending tracks provide any advantage over two straight tracks articulated in the middle, especially given how difficult they are to tension. There were a bunch of tests with articulated tracked vehicles back in the day in Sweden. The Bandvagn 206 for instance would be the same concept but with two separate tracks. Still cool tho.
At 08:50 you tossed the added pivot points out the window by putting the extra guide bearings dead centre. Should have put them on the ends of the bridge no? Also; make your tracks have magnets in them so they stick to the bearings that way and don’t need the things wrapping around them.
You are burning too much plastic in your basement. I am worried you may endanger your health with all that toxic fume. Use proper air duct to maintain fresh air!
On commercial bendy belts I’ve worked with they don’t expand and contract. They just get shorter on the inside while the outside stays the same. This would avoid the bending stress on the pins and the flex in the belt. I think you could get away with spring take up on the top only, and devise a different method of keeping the bottom from falling off. Maybe a bendy L profile guide that hooks into the belt?
You could add a tensioner (hydraulic, spring, etc.) in between the center bending gears and the body-ends they are attached to, therefor passively tensioning the slack by lengthening the robot slightly as it turns. 🤔 If you decide to add an up/down pivot so that the track can bend over obstacles, this solution wouldn't interfere with the new mechanism. Such a mechanism might be achieved with a pair of gears that are stretched along the verticle axis, but over a spherical shape, so that the mesh at different angles. The tensioner would ensure that they are pressed together, too, so that they don't just fall... maybe 🤪
This is really cool. I had designed a motorcycle a while ago that was supposed to use a track like this, very neat to see it in action! Congrats! That would be a good version 2 =)
As I said using an only track in the middle is the only point in developing a bending track. But we're here for science not for automotive industry. :)
What you need is to put the idler on an adjustable spring-loaded mount, so when there's slack in the tracks the idler will push outwards to pull it taught, and vice-versa.
Thanks James, another great video and a cool concept to experiment with. Question about the filament colours: I noticed that the yellows and oranges don't match, was that because of different filament batches, or are they slightly different colours or even textures (i.e. matt vs not)?
That's what I wanted to scream at my phone the whole video. It's crazy that also in the comments no one suggested that simple fix. Everyone is coming up with insanely unnecessary complex things when it's as easy as removing a few links. If you pick up the tank and you have a ton of sag at the bottom, you have too many links
Cool idea with the bend. The solution to most of the problems you encountered (tensioning, treads tending to slide around etc.) is quite easily visible by having a look at a closeup of actual tank treads. BTW: In most of the places were you used a static metal bearing, a wheel with a suspension would help a lot. Looked a bit like a "You have to put 50 bearings in your build" situation. ;) But whatever you like as long as you have fun.
Hi James, your middle-section issue with track tensioning may be solve with the mechanism from Thinkfun Tail Spin. Please have a look at it. Thanks, Oskar
I'd modify the tracks so the piece that comes down can hook, letting you have your tensioning bearing be underneath the track. Would make the print a bit more complicated but could also simplify how it stays on.
What about a caterpillar shap for this robot? If it also could bend uppwards in the middle that would, well mostly look awesome but might also help with the terrain capabilities! But yeah would also be quite a hard overengineering problem... ^^
Seems like for each of these projects you develop 10+ new 3D printed designs. Truly incredible! What's your design process like? And how do you design complex interlocking pieces so quickly? Would love a video on this!
You made the track bendable, constructed a geared chassis but you didn't build bendable bearing guides? On the top and on the bottom respeectively: one singular compliant part that holds the bearings for that bend. Maybe a zig-zag with the bearings at the corners? Or a thin but tall bendable spine with "ribs" holding the bearings the right distance apart? this build has potential to become the next ridable centipede ... =)
If the links between the sections where rounded, or more spherical I suppose, you could make them pivot also, which I think would help rather a lot. Furthermore, it should be possible to design independent drive section, to joins as many together as needed. Difficult to put into words exactly, but in my head it seems perfectly simple.
This reminds me of the tracks used on the Cruiser Light tanks Tetrarch tank and the later Harry Hopkin tank, where they had two steering mechanisms, one was standard skid steering, and the other was bending the tracks, i think it would've worked similarly to the ones presented here although i can't really find online sources in regards to the Tank treads use on either of the aforementioned AFVs. one suggestion i have to tension the tracks is having an adjustable or spring tensioned roller wheel underneath the tracks on the fixed bodies, so as to try and keep the track in place, either that or reducing the space in the track treads that houses the track pin on the vertical axis so it doesn't move as much up and down but still maintaining left and right.
The tetrarch turned the outer wheels, and the inner wheels tilted in a funny geometry to tighten the turn radius. It gave the tank the ability to turn without relying on skid steer. But since he doesn't have a tank body to get in the way, I don't think he'll need to do any inner wheel articulation.
Instead of printing out rubber pads stuff like that for your tank treads use spray-on rubber bed liner, the volatiles in the formula can sometimes melt plastic. But if you spray tan and really light passes that stuff evaporates before it damages the tread.
What about ##### ## # # ## ######## Then you can have a bearing on the inside push it down (I might have made a bad diagram but I hope you understand it)
Looking thru the comments, I like the idea of making the idler an adjustable tensioner. Would only have to redo the mounting plates (add a slot, adjust the length, & a mechanism to move the axle). Great work!
The Tetarch did turn the outer wheels, and the inner wheels did a funny geometry tilt to do so. It allowed the tank to turn on roads without using skid steer.
this was used in some real tanks btw they did it by holding the two ends stationary and pushing or pulling the roadwheels closer or further from the chassis
A spring tensioner pulling the track up could do if you keep the two top bearing rods. Also a single spring tensioner that pulls the both ends apart could work, this is how some small excavators are tensioned. Tanks often tension their tracks via the suspension springs and a tension setting that works like the sprung tensioner on a mini excavator that i described.
One thing you can potentially do for track tension is make the side with the roll wheel adjustable so that you can extend it a bit to tighten up the track.
Weird! It is as if they tried all these ideas back in the last century… and found out that: Two belts with individual motors and regular tension mechanism is the peak of function over form and need. Hmm. 🤷🏼♂️🤪😂
You should take a look at a Bren Carrier as they had a mode of steering based on warping the track. It used the road wheels to gently curve the track while keeping the ends straight.
An interesting idea. But now it just makes think how easy it was to sell tank ideas to the Germans back in WWII. Because they experimented with all kinds of things. LOL But would be fascinating to see how this idea can be improved on and fleshed out.
You’re overthinking the tension a bit mate, just use springs to push the sprockets outwards to hold the whole system in tension or even between the two outer sections and the orange pieces with the half gears.
Another fun project. How does this compare with commercial vehicles that already exist? Are all these projects as genius as they seem, or over engineered?
I don't think there's any commercial vehicle like this. The Guardian S robot has tank treads at each end of it, but none in the middle sections. Russia has the Hamyak, and there was the 1939 Helaitre, but they didn't articulate the track for turning. The Tetrarch articulated the treads, but it's a tank... so yeah, nothing like this existed... yet
@@1944GPW Yes, they warped the track by sliding the inner wheels in and out and again it's a tank... I wouldn't really consider that a "commercial" item as it is a military item...
Making the underneath of the treads hook-shaped would allow you to put the hold-down bearings inside the track, thus avoiding problems with it getting caught on objects.
You could put neodymium magnets In the underside of the track and the on mount points under it on the frame. That would hold the track down and possibly constrain the belt when steering.
@Elio no, not at all. I use them in a very very similar manner on a conveyor belt system at work. You can't pull appart but magnets will happily slide over each other. Especially when embedded in a plastic belt segment to reduce their strength but keep enough of it to hold the track down.
Neat concept James! I'm excited to see what you do with version 2. I bet more sections would provide better support for the tracks. I'm imagining a bendy scissor lift type mechanism of linkages to bend it, it would be wacky!
Give it two weeks and this will be an awesome project! Great start so far. I think solving that tensioning problem will be the biggest part. I think you gotta stray away from tensioning the bottom side of the track and instead find some sort of spring based retention for the top of the tank, either in the middle or the end of the tank
You could do two or three joints to allow more turning, you should also add a screw tension on one side. Allowing you to to extend one side of the track to be longer to create tension, this could work better than external bearings
Do you actually 1st think about projects, or do you just wing it and see what happens next? Sometimes it looks like you fix problems by fixing problems by fixing problems.???
I don’t know much about tracked vehicles, but I know they have a tensioner for a reason. Even a simple bar, a couple of bearings, brackets, and a leaf spring would do the job
This scheme, called track warping, is a very old idea. It was used for steering on the well-known WWII Universal Carrier (aka "Bren Gun Carrier") for light turns, and mechanically combined with track braking for tighter turns. The carrier's centre bogie could slide a small amount laterally, causing the track to warp along the ground. No special loose track was needed, the grouser pin tolerance was enough. The track warping system was improved upon with the Australian WWII LP3A MG Carrier and also on the 1-ton Tracked Truck GS where the front idler wheel was able to pivot a few degrees left to right to warp the track before it touched the ground, reducing the force necessary to steer.
車体が屈曲したときはキャタピラのテンションが上がって、車体が直線状のときはキャタピラのテンションが下がってしまう。 When the body is bent, the tension of the caterpillar increases, and when the body is straight, the tension of the caterpillar decreases. これはキャタピラの左右端に長さ制限があるせいだろうか？ キャタピラの中央の長さを一定にすれば、リテンション機構が完全に不要になるか、小規模なもので済むと思う。 Is this because there is a length limit on the left and right ends of the caterpillar? I think that if the length of the center of the caterpillar is fixed, the retention mechanism will be completely unnecessary or it will be small.
Early snowmobiles were definitively monotracks without steering skis. Cannot find picture, except one in my head. You probably steered by just tilting the snowmobile.
I think for tensioning, you could maybe make the lengths of the end bits variable? Perhaps even connect them to the center pivot with a spring-loaded piston mechanism, so that the system tensions automatically to keep the track tight. That way you could avoid those outside rollers.
This is terrific! Why not print the track in TPU/Flex? My boy and I are designing a little tank scout and planning to use TPU because it complies with the terrain for better grip. Worth it?
What about ball-joint like gears - spheres with gear teeth cut into them, so that there is a vertical DOF similar to the horizontal DOF to improve the traction?
What if you made the frame like those expandable/curve-able package conveyors? Then add springs or something to keep it spread apart and put tension on the track.
Hallo james bruton saya pengemar kamu sejak lama semenjak membuat hulkbuster dan saya membuat kaki hulkbuster terinspirasi ide kamu terima kasih banyak untuk rancangan nya ☺️🙏
Yeah squssing the track 9:39 will cause massive friction and wear 😳 Try adding suspension in the bottom which help the tanktrack be more like a tank track, 🤔 Maybe a deeper track flange? (Not sure the correct terminology...) Might help to keep the track center on the bend, and would help when got the suspension on there. Cool project, woupt make for an interesting single track bike. Would have to have heavy steal curving around the track, to safe guard the rider. 😱 I don't want to think, of a person getting wrapped and jammed in the track 😔, it's would shreed them and jam like those failing escalators in china! 😮😱 😳 Best to make it remote control away from fingers, limbs and giblets... Try making 3 small tracks and turn the ends around the center one. Then can turn much sharperas the 3 tracks would be independent from each other.
There are so many ways you could improve on it.......but i also wonder: is it possible to make it also bend in the vertical axis? But that way you probably wouldn't be able to get rid of the tension bars. Also, you should just try running it without the track!!! It'd solve most of the problems, and probably be more efficient, more flexible, but clearly, that's not the project.... Anyway, a good proof of concept 👍
Awesome! I've thought for a while about how a "bicycle" with a single bendy track could be made. (Mostly because this would be great for riding in deep snow!) No solution yet, but this is definitely going in the right direction... A compliant rail with a T-shaped (or Y-shaped) slot and appendages on the track-sections that fit into it would certainly solve the problem of the track coming off, without the problems of your current outside metal bar. To make the rail flexible enough, it would need to have only a continuous backbone in the middle, while the sides that actually guide the appendages would be serrated.
I suspect if the treads weren't flat/smooth where it grips the ground it'd go over things much better- like tiny spikes similar to Footballing Shoes- not much, just not smooth. Then like you mentioned, rubber would probably help as well. Either way, this is very impressive- you earned a Sub ;P
There's actually a vehicle that drives with a 60cm wide bendable track! It's called Flextrac MPV or Finncat depending on the model year. I got some videos of that vehicle on my channel if you want to see how it works. It's quite an interesting way to steer, really good at driving through snow and mud though!
What about trying an expanding articulating pivot point? So the two "halfs" - drive and idler - move apart slightly. Maybe change the center to a ball slot track. Ie.. 2" ball placed into a track, that is say 3/4" in depth at center and get shallow towards the outer ends. This might, in theory, give you a rolling expansion wedge and might help with the tension. Or I might have a really bad idea here. ..... where did I put that blasted engineer again😅...lol
Imagine... A vehicle with two bendy tracks, able to bend towards each other to let the vehicle pivot in place. But they can also bend outwards for stability at the cost of immobility... Unless... You could let them bend down to lift the thing up off the ground, and at those four contact points you could drive "sliding" sideways, etc depending on drive directions... So bring back the omni-wheeled treads too! A monstrously complicated but monstrously cool monster of a tank walker thing.
why not make it where the center is thinner compared to each end? nothing is really restricting it to be a constant measurement from one end to the other, it would act like two tracks but it is just one, that is going up and down its own tracks. should fix the issue of it getting stuck. you might have your reasons to keep it in be like a worm though. just a suggestion.
That's one way to defeat naughty viewers skipping your baked-in ads, use the advertised product over and over and over again during the entire video. Gotta admit i myself have gone through a "ball bearings into everything!" phase of my life... but this is going nuts with them. One could legitimately say, unbearable.
Your projects are amazing, that's why I have subscribed, but the more I watch, the more I get feeling you should make better research about topic you make, cause you make errors that are sometimes fatal for your projects I'm not sure how much time you spend searching for this exact project, but steered tracks existed in WW2 light tanks, so I recommend reading some info about these if you ever want to continue this project Geometry of steering, the way track pins in track links works to allow steering, how they tension and make sure track won't fall of
Just as a "quick" fix to keep most of the existing hardware while you revise the design, what if you got rid of the the bars between the wheels acting as tensioners so theres a big gap between them, and printed a new track with an extension that goes through that gap, and goes back around the outside of the tension wheel? I made a rough diagram below, but I think you understand what I'm saying, the track segments would be a taller i beam shape with a gap for the wheel bearings to slot inside of as the track passes around it. ======== ]O === O[ ]====== [
Love your videos, but side note why do all these channels produce bad prints (IMO). I see a lot of bad walls and failures. I'm simply curious because I spend way too much time and filament calibrating for perfection at any speed.
It is an interesting experiment, but it probably defeats the purpose of the track, having two independent pairs of tracks on each side of a tank like this might maintain more of the grip and weight distribution. An advantage of such a non-conventional system might be to be easier on the pavement. However, I think regular tanks, excavators, etc. already don't damage it very much so... It is still interesting though!
I enjoyed watching this little experiment. It involved solving some other problems along the way, i.e. spinning motor housing and such. Another idea became obvious after you squeezed the truck in the middle ...we do not really need one piece of truck...why do not we split one truck into two...you eliminate problem of keeping truck on the rollers and its tension. Or yet, another idea is to install the two half-gears on extensible shaft with springs that would keep the truck's tension even when it bends.
