Hunter class defense spider size or bigger?
Hunter class is about the size of a respectable car and can be ridden in.
That at a minimum. Consider: The easy way to power the spiderbot would be to just drop a standard power plant into it.
I might not want to go with the full lunar design, though. There really isn't a problem with heat flow, so spherical may be wasteful from an ergonomic viewpoint. More crablike, possibly.
And the ultra-redundancy wouldn't be needed, either. The arms could be dedicated, as also the legs. Still insectoidal, though. It's a stable platform that can maneuver anywhere.
One pictures a forest of levers to control the hydraulics. Not my way. I'd have the legs interconnected, and still controlled as I described it, with the operator using a harness.
The machine merely follows the operator's motions. When he walks, it walks. When he picks something up, the machine picks something up.
My design simplifies the matter of balance that a full-size mechanoid would have. If you've seen "Iron Man", the nemesis configuration that Tony Stark faces would be a typical mechanoid design. It's big so that it can be strong, but for a typical backyard work project it wouldn't be practical.
Picture something more like a zero-radius lawn mower, with legs instead of wheels, and you're getting closer.