LEGO GBC Module "To and Fro"

This video shows my latest Great Ball Contraption (GBC) module which I have called "To and Fro".
Definition:
to and fro /ˌto͞o ən ˈfrəo͝o/
adverb - in a constant movement backward and forward or from side to side.
verb - move constantly backward and forward.
noun - constant movement backward and forward.
I wanted to design a GBC module that I hadn't seen done before. The main feature of this design uses a string and pulley system, with different levels of mechanical advantage implemented to get the movement and timing of the mechanisms just right.
"A great ball contraption (GBC) is a machine which receives soccer balls or basketballs from one module and passes them to another module, rather like a bucket brigade. Modules built according to the GBC standard can be assembled into a collaborative display without pre-planning or modification. The GBC standard is minimal, permitting the builder great flexibility in designing the mechanism by which balls are moved from the input to the output."
greatballcontra...
This GBC module adheres to Type 1 of the GBC Standards.
greatballcontra...
I synced the video with the music as much as I could (within reason). I changed the tempo of the music so that it lines up with the tempo of the GBC module (1 ball per second). Each camera shot is a multiple of four seconds, and the changes of the camera shots coincide with the changes in the music.
Music:
"Killers" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
creativecommons...
I hope you enjoy. If you have any feedback or questions, please leave them in the comments of this video.

[@WilliBadenhorst]

The alarm system for jamming is just spectacular.

[@slfroden]

Thanks. If you'd like to see more information about this alarm system, I have created another video that goes into a bit more detail: kzbin.info/www/bejne/bGSXnaCjgNaFrZY Enjoy :-)

[@PaulKlop]

This GBC is so amazing! Great job, I really like that everything is controlled with one motor.

[@loookclick938]

Very impressive model and a good solution to move the balls up 2steps at a time such that the movement is slow and steady. I like the use of strings. Great work

[@sqiddster]

Very nice! Love the use of pulleys here

[@anthonymunoz6013]

Sprctacular! Love the use of pullies in this one

[@stephanebarillet2909]

GX

[@CrazyGamingHub]

Thank for your video . Have a nice day, Liked & Shared your video ;)...

[@legotechnic27]

very nice design :) I really like the alarm you put into it!

[@slfroden]

+legotechnic27 - Thanks :-) You can see more about the alarm in my previous video: kzbin.info/www/bejne/bGSXnaCjgNaFrZY

[@hallbricks]

This is awesome, I love the jam alarm!

[@Nico71Fr]

Very nice ! congrats !

[@philipsmith1041]

i like this one because every time there is a ball moved. many others i have seen are random and a ball isn't moved every time

[@DocWorm]

I was going to ask if you by chance were at Brickfair Virginia or saw coverage from the event, because I made the same lift mechanism for my module, also in the hopes that it was something creative and new. But I see you haven't seen somebody do this before. I actually took the idea from a non-lego GBC designer. Unfortunately the only solution I came up with to get each lift to move to the precise location involved compressing shock absorbers, which ended up straining the motor over time to the point where the motor overheated. I think it's very funny that yours includes a brand-new alarm system to counteract this problem, even though I doubt it was a serious issue in this particular design! Yours is impressively reliable, and when I eventually get around to fixing mine for the next convention, I'll surely implement some of the ideas shown here. I love the use of pulleys, it's a very smart way to be able to work out of system, as I was finding I needed very specific lengths of piece that didn't exist.

[@slfroden]

+Steve The Squid - No, I didn't go to Brickfair Virginia. I just watched the video from Beyond the Brick, and I think I can see your module at about 17m05s (kzbin.info/www/bejne/paiVooeFpa53o5Im5s). Nice work! I'd be interested to see how your mechanism works. Do you have any more footage or photos? When I was creating this GBC module I came up with a few different ways of performing the same motion, but went with the pulley system as I hadn't seen anybody do that before, and it seems to run fairly reliably.

[@DocWorm]

Yep! That's mine in the video. Unfortunately I forgot to take pictures or save a video of it before packing it up, as I'm moving this year. The 'buckets' are all attached on pivots to a technic liftarm like yours, which slides up and down on guiding axles. For some reason, I wanted each bucket to be tipped individually instead of just having them all connected, so there's pins in the middle that tip each bucket as the bucket is pressed upwards against it. In the back, the motor raises and lowers the liftarm that the buckets are attached to. The lever that lifts and lowers the buckets is a shock absorber, so it can push the buckets all the way up against the tipping pins, and then some, to ensure reliability. Unfortunately that put way too much strain on the motor, and in the video you linked, my module was already running at about half speed. I forgot to ask; why are there two sets of gear treads on each side of the pully system on yours?

[@slfroden]

+Steve The Squid - The chain links (gear treads) are only on one side, and doubling them up reduces the force applied to each one so they are less likely to come apart. Also I wanted to keep the frame symmetrical, and on the opposite side there are a set of gears that reduce the motor speed which take up a width of two, so I wanted to keep this side the same width. It works just as well with only one set of chain links though.

[@loookclick938]

Steve The Squid Haha I made a video, and a gbc design very similar to this uploaded on july 2013. I guess I can say (FIRST) HAHAHAHA

[@slfroden]

+GBC cuts - I hadn't seen your modules before. I like the progression that you made between your first version and second version. I guess we all came up with similar designs independently, even though the mechanisms that we used are different. I haven't seen this type of GBC module at any of the Lego conventions that I have attended, so I guess this is still a rare type of module.

[@hellosumato3965]

world's most satisfying vid

[@slfroden]

+Alex R Berrettoni - Thanks. Maybe I should use that as the title of the video!

[@hellosumato3965]

Yeah!!😀😀😀

[@LegoGBC]

Great job!

[@charleslaine]

Have you ever posted a set of build instructions for this? I want to see more how you achieved the reciprocation between the two halves and how that syncs up with the yellow lift arms.

[@charleslaine]

Thanks! I found it and am using the LDraw file to try and recreate this. I've already put together the hopper, with a few enhancements to make it easier to adjust the ball paddles. It's a challenge though, since Technic builds have to be done inside-out. I keep having to take stuff apart in order to make it all fit together! LOL. What kind of string did you use? Is it just a normal lego string that comes with a kit such as the Unimog's wench? Or did you get some kind of heavy duty stronger stuff?

[@slfroden]

+Charles Laine - Sorry for the delayed reply - your message got flagged for review for some reason :-/ The LDraw file was created to show the framework, mechanisms, and electrics separately. I also tend to create a new sub-model for each new 'angle' as it makes it easier to edit the file in MLCad, but not necessarily easier to use as step-by-step instructions. I actually used 3rd-party string, but Lego_GBC_NL (on the EuroBricks forum) found that thinner string worked a bit better than thicker string, and x77ac50 worked well (which is what is included in the Unimog set). I have had this GBC module running for several days at various events and the thin string doesn't show any signs of fraying or wearing out. If you have any further questions, please let me know.

[@charleslaine]

Thanks for the info! I'm very close to having it fully working. I'll post pics and a vid when I get it completed. I spent a LOT of time on the hopper/base of the module, trying to come up with a framework that is more stable to reduce backlash. I think I have a pretty good solution that turned out to be fairly simple and straightforward. My build is now very modular. The hopper unit is easily divided into three separate components, which allows very easy construction and tweaking. I have been astounded at just how precise the base mechanism needs to be. The balls coming out of the hopper and down those flexible tubes... it has to be so perfect. The speed of the balls is determined by the amount of "kick" from the little swingarm combined with gravity. I found that just changing one or two tiny little bits would cause the balls to arrive when the oscillating cams were in the up position. LOL. But I finally got it all worked out. I do have one last question, and it's regarding the ladder's string drivetrain. In your video, there are rubber bands attached to the end of each string. What are those rubber bands for? Just to allow some give in the string? I was just wondering if it was really necessary, and if so, perhaps I could figure out a way to incorporate a more predictable LEGO shock absorber into it somehow.

[@slfroden]

+Charles Laine - I'm glad that you are getting it to work. To be honest, after having it run at several expos, there are a few things that I think I would change too (mostly related to the hopper), so I'm interested to see the changes that you make. I added the spanners for the exact reason that you mention - the timing from the 'kick' from the swingarm and gravity was too unreliable, so the spanners are there to let the balls sync with the ladder properly. I tried many different pieces before I settled on the spanners, but others have mentioned that standard axles also work. The differential/worm gear at the bottom are also there to aid in the adjustment of the timing between the hopper/spanners and the ladder. I've also found that the angle of the surface that you have the model on also makes a difference and the timing needs to be adjusted accordingly (a pain at expos where the tables are never level). When the timing is not right, balls go everywhere! The rubber bands were needed during development, but not so much in the final model. In the video you can see that they do stretch ever so slightly (@1:56), and the amount that they stretch actually depends on the thickness of the string. If you use string that is thin enough the rubber bands should not be needed, but since I had already added the rubber bands to the string during development I just left them there.

[@babascustomlegocreations8837]

awesome!

[@GreenGeckoLegoTechnicWorkshop]

Where do you buy your GBC balls? Thanks

[@slfroden]

+Green Gecko Lego Technic Creations - I got mine through my local Lego User Group (LUG). The ones that I got were originally from some Lego Friends sets, but they have also been in a few other recent Lego sets too. If you don't want to buy a whole set just for one ball, you might want to check out the Bricklink website and search for 'Sports Basketball' or 'Sports Soccer Ball.

[@HoshikawaHikari]

I've tried to make sth. like that before but it didn't work.

[@huetobi]

Why this music and not the original sound?

[@slfroden]

+huetobi - When I was recording I wasn't concentrating on the sound recording, so it had lots of background noises and was recorded from different locations (wherever the camera was positioned) so the quality and amplitude of the sound was all over the place. To do proper sound recording I would need a better microphone and a boom or some other way to mount the microphone in a static location. Also, all that you would hear is the sound of the motors spinning and the balls moving.

[@xXTheDarkSniperXx]

where did you buy that balls

[@slfroden]

+xXTheDarkSniperXx - I got mine through my local Lego User Group (LUG). The ones that I got were originally from some Lego Friends sets, but they have also been in a few other recent Lego sets too. If you don't want to buy a whole set just for one ball, you might want to check out the Bricklink website and search for 'Sports Basketball' or 'Sports Soccer Ball.