GBC Stair Module for bigger balls

[maehw]

Hi all!

I want to build a small lift module for my child that lifts the balls of a ball run back to the top. At least.. this is meant as a proof of concept as I may easily run out of tiles.

Please be patient with me as I am not really familiar with GBC terms nor with Technic tile names in general.

As a basis, I've watched some YouTube videos about GBCs and more specifically about GBC stair modules and the crank-slider linkage mechanism at its core.

[bricknerd.com] The Five Core Mechanisms of Great Ball Contraptions is a great starting point.

I've tried to come up with something on my own for the balls I'd like to transport: they roughly cover an area of 6x6. This is what a step could look like (left to show the area, right to show another step with some slope):

 

In my understanding it's important that the ball does not sit in a stable state but is likely to roll over to the next stair, when accessible.

 

However, this is not my core problem at the moment. 

 

As you can see, this is just a work-in-progress. The idea was to start with a frame and the steps and get the mechanism working. Theoretically there would be space for 7 steps, but I am more likely running out of tiles before this thing gets finished. Therefore, I've tried to make a proof-of-concept with the first two/three-ish steps.

I am having trouble with the guides for the linear motion. They are not stable enough/ don't seem to be a good fit.

 

The images are available on Bricksafe: https://bricksafe.com/pages/maehw/gbc-crank-slider-stair-module

 

Do you have any idea how this could be improved? Especially, any suggestions about relations of dimensions of crank arm and connection rod or fixture/guidance of the slider?

Any other ideas how to get started? (May be: "follow a tutorial for a stair module for the standard GBC ball size (which?) and try to continue from there").

Need more pictures? Let me know!

Edit: As you may see, I nearly solely have Technic bricks from the late 1990s/ early 2000s available.

 

Everything is appreciated

Cheers,
Mäh

Edited 11 hours ago by maehw

[Stereo]

"Double shear" linkage (one link shaped like a fork, connecting both sides of the other link) will improve mechanism smoothness quite a lot, cause it gets rid of twisting forces, which make all the pins bind up a little bit.  You have lots of space to work with, so instead of the single blue pin-axle connecting rods, you could put two of those around each slider.  Or you could have one lead to 2 sliders.  When that's not possible, using thin liftarms gets the centres closer (along with the axle-pin connector that's only a half-thickness pin)

Dimensionally, the connecting rod should be as long as possible, as the straighter a line it travels in, the less side-friction it generates on the slider.  Likewise, the farther apart the 2 guides for the slider, the less force ends up sideways on each.  Though of course to do both at once you'd need a taller mechanism.

If you have ability to get modern parts, the 60474 round 4x4 plate with hole in the middle has rounded off edges to the underside of the hole, so they'll work more smoothly than classic Technic plates -  I can't say how much this would improve things but the lower slider hole is where I'd test them.

Edited 3 hours ago by Stereo