Star washers are a better choice than the split-type "lock washer", but then I am totally biased against split washers in any use. At all. Their stated method of operation is either to act as a spring when the nut becomes slightly loose, or to gouge into the nut and base metal to resist turning. In the former case the joint is already loose, the only thing that the slip washer has done is attempt to retain the nut. In the latter case, have you ever cut yourself on those gouges? Painful and not fun. To add insult to injury, most split washers split a second time and then evaporate. Now the joint is loose and the washer is the direct cause.
If you need something better than a simple jam nut, use a nylock or lock-tite. Though it sounds like a simple jam nut is working for this need.