I believe you’re wrong to assume the gender is a property of the thing the word refers too, it’s a property of the word itself. Synonyms can have different genders, like “vélo” is masculine and “bicylette” is feminine, both mean “bicycle”. “Vagin” is masculine. There’s no 100% consistent mean to determine a words gender, but helpful patterns that are right most of the time would be more in the word’s ending.

To take the example of “machine”, I can’t think of any word ending in “-ine” that isn’t feminine, safe for some Russian names.

Also, if a noun doesn’t end in “-e”, it’s most likely masculine. But the reciprocal isn’t true!