Knex Big Ball Factory

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KNEX Big Ball Factory

I have spent some time creating LEGO models in Inventor. The are nostalgia projects of kits I had growing up. I started to find creating LEGO CAD models frustraiting because every kit contains some uncommon pieces. KNEX is much more standard so I decided to have a go creating some KNEX assemblies from my childhood.

This page is for the KNEX Big Ball Factory. It is one of the large sets. It took me and a couple of family members all of boxing day one year to assembly this. We all had sore fingers afterwards.

The CAD model is not quite complete at the moment. It is missing the chain and the balls. I have no immediate plans to add them, but I am sure I will get to it at some point. The trouble is I do not have any to hand to measure. I didn;t actually measure the other pieces, instead I found them available online. The dimensions were off a little so I adjusted them so they would at least fit, but they don't have the same tolerances and clearances as the real things. It works, but it isn't as good as my lego models, which would fit the real thing if I ran them off a 3D printer.

The individual components here use iMates so the rods and connectors snap together. The constant clicking noise my computer made while I assembled this drove my wife crazy! The only problem with doing this in CAD is the inability to flex the components. The frame fits together just fine, but on the real ball factory there is a slight flex in some of the components to get them to fit together. You will notice if you look really closly at the model files that a few of the more intricate sections are not connected perfectly at each end.

I will come back to this project at some point. I plan to use this model to see just how hard I can push the dynamic simulation tools and I will also be using this model in my Unity Virtual Reality experiments.

I have posted the model files on GrabCAD should anyone want to download them.

https://grabcad.com/library/knex-big-ball-factory-1