[GBC] To and Fro

[Splat]

Hi Everyone.

I'd like to show you my GBC Module that I made 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 timing of the mechanisms just right.

This GBC module adheres to Type 1 of the GBC Standards, processing one ball per second on average (http://greatballcontraption.com/wiki/Standard).

 

The main focus of this module is the 'ladder' in the middle which raises and lowers using string and pulleys.  You can see this in the video between 1:48 and 2:04, and I'll try to describe what is happening.

• First of all, the end of the string is attached to the frame, and goes down to the cranks.  The exact length of the string can be adjusted, similar to how guitar strings are tightened.
• The cranks have pulleys on them, so the string actually moves twice as far as the diameter of the cranks as they rotate, but at the same time the force is halved.
• Next, the string goes up to a pulley fixed on the frame, then down and around another pulley, and back up again.  The bottom pulley is attached to the moving part of the 'ladder'.  This halves the distance that the 'ladder' moves compared to the string, but also decreases the force required to do so.
• The string goes over another static pulley at the top, and then back down to the outside edge of the moving part of the 'ladder'.  To move the outside edge of the 'ladder' requires the full force of the string to move.

Due to the mechanical advantage of the different parts of the pulley system, the 'ladder' wants to move up first since this takes less force, but once it hits a stop at it's upper limit, the string then provides force to the outside edge of the 'ladder' which causes that last little 'kick', which lets the balls roll to the other side.

 

This module can also be broken down into four smaller sections for easier transportation:

1. The motor which is part of my Automatic Motor Shutoff and Alarm System,
2. The 'hopper' and 'ball diverter',
3. The 'ladder', and
4. The 'waterfall'.

There is only one M-motor powering this module and that helps ensure the timing of each section is in sync with the next.
The motor section is attached to the 'ladder' section with a universal joint, and the 'ladder' section is attached to the 'hopper' section with a CV joint.
The 'waterfall' section doesn't need any motor input, so it is attached to the 'ladder' section with a single axle that allows it to be detached easily.

Between the 'ladder' section and the 'hopper' section is differential (hidden away underneath), and I can manually adjust the rotation of this differential via a worm gear to get the timing between each section just right.
Apart from this one worm gear used to make timing adjustments, I haven't used any other worm gears as I have seen the damage they can do to GBC modules if something gets jammed (although, in theory, my Automatic Motor Shutoff and Alarm System should stop this from happening anyway).

There are quite a lot of gears within the drivetrain, but it runs quite smoothly.  When I was creating it I thought the weight of the 'ladder' would cause a lot of strain on the motor, but when one side is going up gravity is making the other side go down which cancels out a lot of the strain.

Jams sometimes occur in the 'hopper' and 'ball diverter' sections, and are typically caused by too many balls in the hopper, or the timing of 'ball diverter' not being adjusted correctly.
I have had this running at a public expo that my LUG held, but I was too busy to baby-sit this module, so it was only running part of the time, but when it was running it ran without issue.

 

This is the first GBC module that I have made, so I spent a lot of time trying to get it working consistently.  I hope you like it.  Any constructive feedback/comments/questions are welcome.

 

UPDATE:  I have created an LDraw/MLCad file of my GBC module.  Read more here.

 

Music:

Spoiler

I hid this part as it relates more to the video editing than the model itself.

I synced the video with the music as much as I could (within reason).
I changed the tempo of the music to 120bpm (beats/minute) so that it lines up with the tempo of the GBC module at 1 ball per second = 60bpm (balls/minute).
Each camera shot is a multiple of four seconds, and the changes of the camera shots coincide with the changes in the music.

The music that I used is called "Killers" by Kevin MacLeod (incompetech.com), Licensed under Creative Commons: By Attribution 3.0 License http://creativecommons.org/licenses/by/3.0/

 

Edited November 30, 2016 by Splat

[Leonardo da Bricki]

I have no experience building GBC modules, but this is one of the coolest ones I have seen. The pulley mechanism is fascinating, and it appears to work great. Impressive that it all runs on one motor. The built-in alarm just makes it even better.

[RohanBeckett]

VERY well done!

Although I have seen the basic L-Beam mechanism before.. you have build an excellent all-round mechanism for it all!

 

and as someone who just spent 4 hours last night, working on a custom GBC Module.. I know the work that goes into these things! :)

 

oh.. and love the auto shutoff system!  might have to borrow that idea for a few jammy modules I have!

Edited November 23, 2016 by RohanBeckett

[Minique85]

This is an excellent and ingenious model. I tried to build much simpler models and was surprised with the complexity of dealing with jamming and balls that decide to jump off.

So the reliability seems really good, and the motor safety mechanism is super cool.

Great job on the video as well.

 

[The_Brown_Hornet]

What and incredible GBC, very well done

I particularly like your use of strings to make the movements and the whole GBC seems to run very smothly

[Philo]

Awesome module, especially for a first one! Not only the mechanisms are clever, but the aesthetic is very good too. Would be worth some building instructions ;)

Now THE question: does it work fine with soccer balls too? I guess the waterfall counterweights would have to be tuned. Sorry, watched again the video, I thought it was Zamor spheres!

Edited November 23, 2016 by Philo

[wissamms]

Very well done, bravo

[Blakbird]

Incredibly well done design.  Fun to watch, clever solutions throughout, and even looks nice.  The automatic shutdown is awesome and should be part of every GBC.

[agrof]

Beautiful, and so is the presentation as well, hat off!

Love the jamming alarm function, very clever. I get more and more involved in GBCs, thanks for such impressive builds.

[MajklSpajkl]

That s really nice module! Well done on the whole idea! I like that auto-stop function a lot!

Best regards, miha

[Lakop]

i enjoyed that video a lot! Very well done.

H

[Splat]

Thanks everyone for your kind comments 

The 'Automatic Motor Shutoff and Alarm System' seems to be popular.  The nice thing about it is that under normal use it just passes through the motor's power with very little added resistance.  The gear ratio doesn't change either, so it is easy to replace any existing motor with this system without having to make any major modifications.  The clutch in the middle only slips for a split second before the motor turns off, so the parts used to make the clutch aren't being worn out either.  It is great for mechanisms that have constant loads on them such as GBCs, but not so good for mechanisms that have variable loads such as vehicles.  Overall, I'm pretty happy with it 

19 hours ago, Philo said:

Would be worth some building instructions ;)

I've only made fully detailed instructions for one of my models before (my Technic Water Strider), but I'm not very efficient at making them so they take me a long time to create.

I could create an MLCad file if someone else would be willing to turn that into instructions.  Let me know if you want me to do this.

 

[RohanBeckett]

the auto clutch.. any chance of getting a few photos from another angle?  can't quite see what the main switching yellow liftarm connects to, on the other side of the diff

 

I'm still looking for a mechanism that, upon jamming.. will run reverse for a second.. and then continue back in the original direction..

 

[Splat]

13 minutes ago, RohanBeckett said:

the auto clutch.. any chance of getting a few photos from another angle?  can't quite see what the main switching yellow liftarm connects to, on the other side of the diff

Does this help?

Under normal load, the tan spider gears within the differential spin at the same speed but in opposite directions, but the differential cage doesn't spin.
Under excessive load, the clutch slips, causing the spider gears to spin at different speeds, and that causes the differential cage to spin (a tiny bit).
When the differential cage spins, it tuns the 16-tooth gear down the bottom, which rotates the black 2L liftarm, which moves the yellow liftarm and the other black 2L liftarm on the left, and that is attached to the first switch (which turns on the alarm).
The tops of the switches are linked so that only one switch can be turned on at a time.

Let me know if you have any further questions.

21 minutes ago, RohanBeckett said:

I'm still looking for a mechanism that, upon jamming.. will run reverse for a second.. and then continue back in the original direction..

For a purely mechanical solution, would something like the mechanism in this ladybug work?

I have a few other ideas too, but I'd have to build them to see if they would work.  I'll see what I can come up with.

 

PS.  Are you going to Brickvention in Melbourne in January 2017?

[Philo]

Quote

I could create an MLCad file if someone else would be willing to turn that into instructions.  Let me know if you want me to do this.

Even if nobody makes full fledged building instructions a LDraw model would be a big help...

Hint: maybe it would be the opportunity to try LDCad that would make strings and chains MUCH easier to create...

[djm]

14 hours ago, Splat said:

I could create an MLCad file if someone else would be willing to turn that into instructions.  Let me know if you want me to do this.

If you are willing to wait 8 weeks or so, I'd be willing to turn the LDraw file into instructions. I've a few things on the go at the moment, hence the 8 week delay. If someone else puts up their hand in the meantime, all well and good. Otherwise, drop me a message when you have the LDraw file available.

Regards,

David

[Splat]

On 11/24/2016 at 8:20 AM, Philo said:

Hint: maybe it would be the opportunity to try LDCad that would make strings and chains MUCH easier to create...

Hi Philo.  I tried to follow your advice, but I'm having a lot of trouble with LDCad (v1.5).  I don't find the software very intuitive at all, but I'm sure that I just have to get used to it over time.  I read through the documentation and thought that I would try to create a chain.  As soon as I add a template part (chain) and then go to nested mode, the software bugs out and half of the interface disappears, including the menu, the toolbar, the compass, the pin, etc, making the software even harder to use.  The same happens if I try to edit the chain submodel directly.  I can't see the little yellow spheres that the documentation says are needed to be able to create the custom sized chain, so I can't resize my chain at all.  For the time being I think that I'm giving up on LDCad.

[Philo]

Annoying... hopefully Roland will be able to understand what happens. My first idea would be a video driver issue, but...

[dr_spock]

Well done.   Very good GBC.   

 

[roland]

11 hours ago, Splat said:

As soon as I add a template part (chain) and then go to nested mode, the software bugs out and half of the interface disappears, including the menu, the toolbar, the compass, the pin, etc, making the software even harder to use.  The same happens if I try to edit the chain submodel directly.  I can't see the little yellow spheres that the documentation says are needed to be able to create the custom sized chain, so I can't resize my chain at all.  For the time being I think that I'm giving up on LDCad.

I'm sorry for the problems you're having. I did some quick tests and the chain template works like it should on my windows (or are you using Linux?) setup so it indeed sounds like an video driver issue. Are you running a very low OpenGL version? Or using an overall older VGA card? It should look like the attached image.

[Splat]

Hi Roland.  I am trying to use the Technic Chain template (part 3711).  I'm running Windows 7 64 bit, OpenGL 2.1.0 (I don't have permissions to update this).  I have also downloaded/unzipped v1.6 Alpha 4 and tried both 32 bit and 64 bit versions, but all I can see is the status bar and all of the rest of the screen is black.  I can still mouse over items and see the description in the status bar, but I am basically running blind.

[roland]

19 hours ago, Splat said:

Hi Roland.  I am trying to use the Technic Chain template (part 3711).  I'm running Windows 7 64 bit, OpenGL 2.1.0 (I don't have permissions to update this).  I have also downloaded/unzipped v1.6 Alpha 4 and tried both 32 bit and 64 bit versions, but all I can see is the status bar and all of the rest of the screen is black.  I can still mouse over items and see the description in the status bar, but I am basically running blind.

I've added a new item to my FAQ section you could try: http://www.melkert.net/LDCad/faq#faq_fbo

However a completely black render area points to an initialization failure, the black area should have a hint label stating this, the above workaround won't fix that.

[Splat]

3 hours ago, roland said:

I've added a new item to my FAQ section you could try: http://www.melkert.net/LDCad/faq#faq_fbo

However a completely black render area points to an initialization failure, the black area should have a hint label stating this, the above workaround won't fix that.

Hi Roland.  I am still running v1.6 Alpha 4.  I updated the main.cfg file as suggested in your FAQ.  When opening LDCad, I can now see the screen (no more black area), but as soon as I go to the Nested tab it freezes for a few seconds, and then the same thing happens as before where the interface items (menu/toolbar/compass/etc) disappear again.  This happens in both 32 bit and 64 bit.

I have already gone ahead and made my chains and string in MLCad.  They don't line up 100%, but are close.  I should be finished with the MLCad file in the next day or so.

[roland]

20 hours ago, Splat said:

I updated the main.cfg file as suggested in your FAQ.  When opening LDCad, I can now see the screen (no more black area), but as soon as I go to the Nested tab it freezes for a few seconds, and then the same thing happens as before where the interface items (menu/toolbar/compass/etc) disappear again.  This happens in both 32 bit and 64 bit.

I have already gone ahead and made my chains and string in MLCad.  They don't line up 100%, but are close.  I should be finished with the MLCad file in the next day or so.

Too bad it didn't work, I think your VGA driver is just too outdated/buggy as OpenGL 2.1 is very old (most drivers are at 4.5). But as you can't update that I don't think I can help you any further.

[Splat]

7 hours ago, roland said:

Too bad it didn't work, I think your VGA driver is just too outdated/buggy as OpenGL 2.1 is very old (most drivers are at 4.5). But as you can't update that I don't think I can help you any further.

Yeah, this is an oldish laptop.  Thanks for helping though.