There's a host of good info here....but one thing to add. There is no magical rule of thumb about what size hole to drill for your screw chuck. The fact that you were turning a piece of yew suggests to me that you may possibly have drilled the hole too small. You state that you use an 8mm hole for a 10mm screw, but you might benefit from re-thinking this strategy. An 8mm hole in a soft, low density wood like lime or alder might well result in the wood slipping, but in a dense, close-grained wood like yew, it might well be too small a hole. OK....you'll get the wood mounted onto the screw without too much effort, but the forces involved in turning are constantly tightening the wood onto the screw, so it becomes a nightmare to get it off again.
These are my thoughts....Les