Chain Sprocket or Timing Belt Pulley

I tested a few low profile belts and found they stretched too much. I didnt want to make the arm any wider and was looking for something low profile so I decided on a small 6mm chain.

Thanks for the reply. I am planning to use GT or SM type timing belt and pulley instead of XL type for all three joints J1, J3 and J4. Whether it will workout?

If cost is an issue like it was for me in Australia, maybe try your local engineering supplier. I was looking on ebay and aliexpress at first... our local supplier was actually a lot cheaper, statewide bearings. I got 10ft of it for $30, it was over $100 from other places

GT3 and similar belts stretched too much? Surprising, I read they are industry standard for some CNC and regarded as a rigid link