I see the last 2 posts...posts 3 and 4, are made by guys with about 5 years experience...apparently you guys have never actually witnessed a cheap plastic spinner "explode"? I don't mean to put you guys down, but if you've been modeling for a long time...in my case about 40 years...you'll see a LOT of things happen. (picking shards of plastic out of your buddys forehead is not a fun thing...)

All plastic spinners (the ones that are entirely made of plastic...with plastic backplates ) should be avoided...
The ones with alum. backplates are OK...

The advice about making sure the prop openings are big enough, and the cone does not contact the prop blades is very good...and make sure the backplate (prop shaft ) opening is a good snug fit on the crankshaft...no excess clearance. Use a bushing if necessary.