Yesterday I printed a test wheel and a mould and poured some silicone:
The mould is PLA because I read that silicone sticks to nylon and doesn't stick to PLA. Turns out it doesn't stick to the nylon very well either, but at least the holes in the wheel ought to keep it in place.
I found that the silicone was not viscous enough to avoid leaking through the holes in the mould, and also the tyre is much too "deep", making it too soft and flexible because it is not sufficiently supported by the plastic. I also thought it would do better with a "tread pattern" on the tyre.
I made the plastic part of the wheel larger so that the silicone layer would be smaller, added a tread pattern to the mould, and made 4 copies of the wheel and the mould. You could use just 1 mould and do the 4 tyres sequentially, but the silicone takes about 4 hours to cure and it is much quicker to print extra moulds than to wait for the silicone to cure.
This time I sealed up the moulds with hot glue to stop the silicone from leaking out the gaps.
The clamps are to hold the wheel down to the mould, as the silicone is denser than the (mostly hollow) nylon wheel.
After the silicone had cured I peeled the hot glue off, then peeled the mould off, trimmed off the excess, and now I have 4 nice rubbery tyres:
Oh, and I've cured my Taulman 910 problems. It prints beautifully. I find that printing at 245 prints just as well as at 260 and does overhangs better, and heating the Ultrabase bed to 45 degrees instead of 60 makes it stick to the bed better. I don't know why it sticks better to a colder bed, but it suits me as I don't have to wait as long for it to heat up. At 245 with a 45 degree bed, I don't need any raft or brim, it sticks just as well as I'm used to with PLA.
Increasing the clearance for the wedge pivot has made it move nice and freely now, so I think the robot is almost ready. It's about 1g overweight because one of the chassis halves was printed a bit heavy, so I'm printing another chassis half with my final print settings (which is 8% infill, 2 bottom, 1 perimeter, 3 top, and oriented the same as the "top" half of the assembled robot) and then I just need to get better at driving it
![Smile :)](./images/smilies/icon_e_smile.gif)