Thanks, QB. The vertical travel looks to be about 2' 6" or 75 cm or so with about 6" or 15 cm overlap. See the YouTube clip linked below.
https://youtu.be/41c36Bbrqsg?t=50I don't mind adding bolts or pins or stops to support the movable top in both positions so the lifting mechanism only comes into play when lifting and lowering and is otherwise under no stress. I did think of a cable system as well, maybe two fixed pulleys at the top of each corner of the fixed portion and one at the bottom of the movable portion and one continuous cable leading back to a central spool turned by hand or an electric drill. One corner would have just one pulley and the fixed cable end, the adjacent corner also just one pulley and the spool, and the cable would go all the way around. I am not entirely sure that would work, however, as I don't know that the travel would be the same on all corners that way. I wold have to make a little model to be sure.
I agree that hard plastic rub strips (or hard plastic skids and metal strips) are a good idea to prevent binding, perhaps even a bit of C-channel with a plastic slide running in it like sail track.
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Matthew Long, Editor
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