I'm trying to work out how many 3711 chain link sections I need to buy to make a loop around 2 x 3647, 8 tooth gears on 15 hole lift arms (on the end holes)? Can anyone help with their size?

Let's see, you want to know how many of these you need to loop around two of these mounted on the endmost pin holes on these: .

You need exactly 40 of the chain links; I just built the assembly with my spare parts that I have.

Edited May 27, 201311 yr by DLuders

8 tooth gears arent good for chainlinks, i suggest you to use 16 tooth gears.

If you use two of the 16-tooth gears (as Zblj suggested), then you will need 42 of the chain links for a VERY TIGHT fit. Get 43 links if you want a loose fit.

How loose is too loose with these things before slip becomes a problem?

Edited May 27, 201311 yr by TasV

It depends on what you are trying to do. When I tried the 42 ea. Technic Links on the two 16-tooth gears, the ends of the 1x15 Technic Liftarm were visibly deflecting inwards. When I added another link, the chain sagged but it COULD WORK on low-torque applications. The Lego Technic Links are relatively inexpensive; why don't you get some and try them out?

Lego gears have a 1mm module, so the chain link should have a pitch (distance from link to link) of around 3.14mm.

OK.. thanks. I'll get 50 or so and play with them with 16 tooth gears.

If it is too tight you could bend your beam under pressure after time. You could also try pulleys.

Use an idler gear mounted on a spring to create a tensioner. This way you get the best of both worlds.

v/r

Andy

Just remember, there are two kinds of chain-links. The newer one is a lot more beefy than the old, and is the one you want. Best thing to do is buying all links from the same lot to make sure they are of the same type. Both fit equally well on 16 tooth gears, but the old (less beefy) one has a lot more sideways flex to it.

-ED-

I like the sounds of the idler gear! Naz, do both kinds go by the part number 3711? If so, I wasn't aware that they came in two different types. I know of the old-style chains that I had as a kid ( 30 years ago), but am after the finer, smaller links.

Naz, do both kinds go by the part number 3711? If so, I wasn't aware that they came in two different types. I know of the old-style chains that I had as a kid ( 30 years ago), but am after the finer, smaller links.

Both go by the same number on bricklink, but I don't know with TLG themselves, as we don't have the option to buy directly in Norway.

What i do know is that the new beefy version has been in every set I have bought after 2011. I will take some pictures for you to show the difference when I get the time.

-ED-