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Acknowledgements

I’ll start this post with two call-outs to Nico71. Firstly, he posted images of his ball counting GBC module (refer to text further below) which provided a substantial foundation on which to base my module design. Secondly, he was gracious in giving me permission to post the building instructions for my module online. I wanted to obtain his approval given my module is, ultimately, a derivation of his original work.

Module video and Building related files

Firstly, a video of the module and links to the building instructions, parts list and LDraw file.

 


Context

I had a desire to have a ball counting GBC module as part of the GBC display for the upcoming 2017 Auckland Brick Show. The primary features of the module were that it would;

  • be a mechanical device i.e. no electronics in the module
  • have discrete digits to indicate the count
  • preferably rotate all digits in the same direction

Development

I was aware that Nico71 had built a GBC Ball Counter and had posted both photos and a video of it running. It seemed a sensible place to start so, after studying the photos and video, I reverse engineered the module to help me to understand how it worked.

I knew that Nico71’s module was not using discrete positioning for digits but I was also aware of Parax77’s video and building instructions  of his Chain Holonomic Drive, which I thought I could use in place of the wheel dials in Nico71’s model. Using the Chain Holonomic Drive however proved to be too unreliable. While I could get it to work reliably with two digits (the ones and tens) I couldn’t get the required reliability for the subsequent three digits.

I subsequently discovered another video of a GBC counter by Nicky Fitzgerald and a second video providing more information about the build.  I attempted to adapt the counting mechanism to replace the wheel dials but this was unsuccessful. The counting mechanism uses the "Technic, Axle Pin with Friction Ridges Lengthwise" in what appears to be a means to prevent the “hammer” from falling due to gravity. I found the amount of friction when attempting to turn multiple dials concurrently (e.g. 99, 999, …) too great for the upper clutch mechanism. However, Nicky Fitzgerald’s design did point me in the direction of the solution I ended up implementing in my module.

Module Design Commonality and Differences
The following image uses a coarsely grained colouring to identify the main elements of the module.

gbc_counter_coloured.png
 

The input bin is coloured red, the primary ball moving mechanism is coloured black and the counting mechanism grey. The primary ball moving mechanism (black) is pretty much the same mechanism as in Nico71’s original module. There are a couple of minor tweaks but nothing that is too significant. The input bin (red) differs in the following ways; it is larger, the agitator mechanism is different (and driven via the addition of a chain) and it contains a mechanism to restrict the balls to drop into the primary ball moving mechanism one-at-a-time and in time with said mechanism. The counting mechanism (grey) is a “plug compatible” replacement for the original, displaying a discrete count of the number of balls.

Next Steps and Additional References
I have used this module in test mode. It occasionally seems to spin a dial a bit too far but then the next ball moves the same dial less. I won’t get to use the module “in anger” until late October. In the meantime, if someone else elects to build this module and has any suggestions for improvements to the design, you are more than welcome to post back to this thread.

Should someone be interested in exploring more about the counter mechanism built by Nick Fitzgerald, in the last couple of days I came across two related videos. Of course, you could always reverse engineer that module and post the building instructions (although after checking with Nicky). 
 

Regards,

David

 

 

Edited by djm
Corrected PDF link.

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Nice work David, I've often thought about a ball counting unit for shows since 'How many balls' is a common question asked by visitors and would certainly be an area of interest watching the numbers add up.

I shall build it and add to my collection of GBC's & give you some feedback.

OMR

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12 hours ago, djm said:

I knew that Nico71’s module was not using discrete positioning for digits but I was also aware of Parax77’s video and building instructions  of his Chain Holonomic Drive, which I thought I could use in place of the wheel dials in Nico71’s model.

I've had vague plans in my head for years to do something like this - I even came up with a linear clutch that fit between stages so that you could adjust/reset the display. I'm disappointed to find out that it doesn't work.

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8 hours ago, Captainowie said:

I'm disappointed to find out that it doesn't work.

I think the Chain Holonomic Drive works but probably requires the torque deliverable from a motor. A ball passing through a turning mechanism coupled with a clutch just doesn't deliver the torque.

David

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Great work! It's great to see another mechanical ball counter, rather than the (much easier to build) electronic ones.

By the way, the link to the PDF file has a ) at the end, which makes the link not work...

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1 hour ago, mocbuild101 said:

By the way, the link to the PDF file has a ) at the end, which makes the link not work...

44 minutes ago, 9v system said:

pdf link does not work. but looks like a very nice module

Thanks to both of you for the heads up. The link should work now.

David

 

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@djm could this be upgraded into an akiyuki style? as much as i would really like to build this it doesnt suit my gbc layout as it doesnt have the double frame on it, i could help you with this 

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