Would questions about use and maintenance of gardening/landscaping machinery be on-topic? I believe we've established that questions about gardening tools are on-topic, but I'm curious whether I can ask here about my riding lawnmower, push lawnmower, tiller, weed-whacker, etc.
To me, equipment / machines are just a subset of tools. So I'd say yes, in general, questions about machines are on-topic.
- "Shopping" questions are off-topic. (e.g. don't ask "What brand of mower should I buy?")
- In-depth maintenance/repair questions may be off-topic. (e.g. I don't think this is a good place to ask "How do I replace the rusted-out muffler on my ancient (70's era) tiller?") Though general maintenance questions probably are. (e.g. I think "What general maintenance should I perform on my mower prior to putting it away for the winter?" is on-topic.)
- Some "uncommon machinery" may wander into off-topic. (E.g. the community here doesn't seem to want to touch "farming" or larger-scale gardening type questions, so "Should I use a subsoiler or a chisel plow on my large (1/2 acre) garden?" may be considered off-topic, though I'd personally welcome some of these sorts of questions.)
- Since we don't yet have many (any?) of these questions, it will probably take several questions until we figure out exactly where the boundaries are.