Iterating Wobblebot (and a side project)

I’ve laid the cable track, planned the new screws and bought another identical to the second…

So, as it turns out, not all lead screws are the same, even when they are supposed to be. The first one I bought has a thread that’s at the right pitch, and the right height, but the trapezium shape is too narrow. This was leading to a huge backlash problem, which I thought I would have to deal with by making anti-backlash nuts. However, the other lead screw, which I had bought thinking it was a pair, doesn’t have that. There’s more metal, and it fits snugly in the nut I have. That means there’s hardly any backlash at all.

I’m still interested in making the anti-backlash nuts, and I have other uses for a tap for that shape of screw, so I’ve ordered a length that I’m going to try to tool into a tap, with the lathe and the mill. Clamping it is going to be a right beggar – I might enclose it in a thermoplastic and clamp that instead.