A client emailed me this evening with a complaint about a chronically lifting bridge thumb on delivery with screw shots. I thought I would share my reply.
"Twist your bridge hand a few more degrees to the RIGHT so it is angled under cue a bit more like Ronnie or John Higgins to give you a better V for the cue to sit in. The thumb pillow muscle will also interfere less with the cue this way.
It also looks like you are also scared of miscuing which is the common cause of thumb lifting. So you should learn to miscue – get an old cue ball and old piece of cloth to place under the cue ball and learn where to strike the cue ball to miscue. Play five to ten miscues at differing speeds but they only count if you deliver the cue as flat as you would with a top spin shot. Start with a cue ball only, and progress to there also being an object ball in a potting position.
If you can miscue on demand and shatter the fear of doing so in the process, you have more chance of being able to screw back on demand.
If we number top spin as +4, centre ball as zero, and the lowest possible screw back as -4 then you could consider aiming at -3 or -3.5 (and not -4) until you build up confidence with that. Then creep lower and lower on the cue ball, with gradually increasing speeds as you build confidence."