[kragen]

Cost is relative; as I noted on here the other day, the minimum legal wage here is US$207 per month https://news.ycombinator.com/item?id=31830007, so even these three toy servos cost a day's wages, perhaps the equivalent of US$1000 for you. And lots of people here don't make even that much, and most people live in poorer countries than Argentina.

The fact that a better product is available at a higher cost is not relevant to the question I was asking, which is what the particular problem is with the cheap servos.

[dekhn]

they have little plastic gears that strip and can't hold even the tiniest weight. They are hard to mount and their rotation is noisy and crappy.

[kragen]

None of those seem like they should be a problem for BrachioGraph except the too-vague "crappy"? It doesn't have the servos trying to lift weight (except for the lifter servo, which has to lift the pen and popsicle sticks) or fighting resistance that can strip their little plastic gears. It mounts them with hot glue, which seems to work okay (surely it introduces uncontrolled compliance that you could reduce by gusseting them with epoxy) and doesn't require them to be quiet.

I'm trying to understand what the problem is with cheap toy servos that leads to problems for BrachioGraph, in enough detail that I could make plans to mitigate the problem.