For a school project I'm trying to build a conveyor belt out of LEGO. I'm currently just working on the design so I haven't ordered anything yet. I think that for my build the 57518 pieces are perfect. My question is pretty simple: is there a way to mount some sort of 'shelves' onto it? I'm completely new to LEGO (and not a native English speaker) so I can't explain it any better. The picture below from the GBC Homepage shows exactly what I'm talking about:

Snippet of picture on GBC Homepage][2]

I believe that the pieces used in the picture are 3873 (not sure). I can also see that in each of these light grey horizontal 'bars' there are two vertical rods that mount it on the conveyor belt itself. The 3873 pieces are not useful for me because they have too many openings.

I spent long times browsing Bricklink trying to find fitting pieces but I just don't know where to look. It would be great if somebody could provide me with links or numbers of the pieces that I need.

  • 1
    no, those aren't the threads in that picture. look at it up close, it's the 57518 threads! thus you can easliy add those black pins and connect beams to it! Commented Mar 12, 2021 at 14:38
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    For GBC instructions you may want to check Rebrickable
    – Alex
    Commented Mar 12, 2021 at 20:05

1 Answer 1


The picture you have does show a 57518 thread link, which is what you wanted to use. For that, you can use the 1/2 and 3/4 pins to attach a liftarm. A 1x5 liftarm would match the width of the 57518 thread. What's shown in the picture is a 1x7 liftarm which allows the module to lift more balls.

For the pins, you should use the 3/4 pins part 32002 to be perfectly legal, but some might also use the 1/2 pins part 4274 to add friction to the connection.

  • Thanks for the reply, it helped a lot! Do you just "know" this or is there some place to check which parts are compatible? Because we are planning on adding 3743 gear racks, but I have no idea which gears will actually fit them.
    – Dries
    Commented Mar 25, 2021 at 14:38
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    Those gear racks, and most gear racks that Lego has, are compatible with the modern regular gears with small teeth. You can drive a sprocket with one such gear (like 3649) via an axle, like this.
    – Pinwheel
    Commented Mar 26, 2021 at 15:37
  • Update in early 2022 LEGO released a friction version of half pins, is canot spin freely for strong and stable connections to my models
    – LKBricks
    Commented May 16, 2022 at 2:58

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