How to make a conveyor belt with LEGO parts?

Question

I am making a small robot with an Arduino and Technic LEGO powered by stepper motors. I am planning on moving small rocks throughout my machine. Does anyone have an idea of what kind of Technic LEGO parts I can buy to make a variable length conveyor belt? I have a lot of gears so it's the underlay that's my problem. Does some kind of elastic LEGO parts exist that I can use for this? Chain-like or rubber or hard plastic. IT Would be best if I could make it as long connected as I want.

Maximum size of the small rocks is about the same size as an 1x1 LEGO brick, so the conveyor does not need to have a width of more than 2 cm.

Answer 1

You will need to decide between 3711 Technic Chain Link and 3873 Technic Chain Tread, or possibly use them together.

Each link of chain is about 1 cm long and 0.8 cm wide and you can get them in packs of 108 (Chain Link Set Product Code: 2000645)

The Chain Tread are wider, but seem to be available only in smaller packs, such as
Set # 9938-1: Conveyor Belt Links (Nominally 36 links)
Set # 1149-2: Bulldozer Chainlinks (nominally 52 links)

Answer 2

In this great GBC machine built akiyuki, you can see 2 types of conveyor belts. The first one is made of the small tread links (3873). The second and third ones are made with the large tread links (57518)

He provides many videos and pictures through his blog and YouTube channel.

Answer 3

Dropping stones onto your LEGO doesn't sound like a kind way to treat your expensive Technic parts; I imagine that small bits of stone and dirt will fall through a belt of Technic Chain Link or Technic Chain Tread , what with them being a chain rather than a belt. This will then lead to other bits of your contraption becoming polluted with abrasive gunk.

Akiyuki also built a brick sorter with a simultaneously tedious and exhilarating video of a machine sorting arbitrary LEGO parts; Photos and an extended discussion in Japanese at レゴのレゴ選別マシン　その1). The conveyor belt perplexed me as I didn't know what it was made of. I thought it might be some kind of fabric or custom-manufactured belt.

Searching the interwebs pulled up this video of an effective conveyor belt built by a small child, comments to which make it clear the belt is paper. It's actively driven by rubber tyres at one end, and idles at the other (I'd suggest using 41531 Technic Cylinder 4 x 4 with Pin Holes and Center Bar as a crowned pulley rather than tyres).

This is the same material that Akiyuki uses as you can see in this low-angle shot up into the tensioning mechanism of the paper conveyor belt in Akiyuki's brick sorter.

Sticky-tape, paper and a smooth LEGO surface underneath the paper to ensure solid support (you don't need to use tiles; try a SNOT technique instead). Presumably you could up the paper to something more robust in the face of having stones dropped on it. You might want to also line the sides of your conveyor to prevent the stones scratching the sides.

Answer 4

Another option is to use LOTS of 60483 Technic, Liftarm 1 x 2 Thick with Pin Hole and Axle Hole as shown in:

https://youtu.be/X89pXBJaPWI?t=7s