Hello pzh11001

I have tested the belts first but beleve me this is to much „soft”and rubber and the joins had oscilations when they moved small way with relative height speed. I replaced belt in all joins where I could. Yes, the sprockets are not ideal in this case but are better compared to the belts. Especilly the chains have very good stiffness. Please, look at Annin’s project where they use sprocket gear as well. I think that polygonal effect is quite small in general construction and in my opinion this is less worst choice in case need to choice between stiffness and some linear and smooth movement. I have tested my robot in many cases of movement and worst issue I have found in whole construction of home made robots is the play in the joins.

In my post above I presented my second version of construction robot arm. In the begining when builded my first arm I used belts and replaced these with chains in second version and it was a good decision.

The chains needs to be lubricated for it’s proper work and they don’t stuck when rotating – beleve me. I tensioned chains quite hard and have no play in joins at all then. I think my construction is not rigit enaugh to stop rotating sprockets :-)

Now I work with third version of robot arm where I updated J4, J5 and J6.

The arm is testing with 4 kg weight metal plate. The biggest problem is the rigit. With belts this is imposible to manipulate that weight.

Regards