Cool tube shortening?

Has anybody ever cut a cool tube down? My growroom has a 3x3 footprint so by the time i get the thing ducted ive got some nasty bends in my flex duct. With the longest bulb in the tube i have damn near 12" i could cut off. I thought about trying the "burning string" https://www.youtube.com/watch?v=xUk1M1wQsns method to snap it off but dont want to destroy a tube if i fail.

try searching for "Ronco Bottle and Jug Cutter" on ebay

https://www.youtube.com/watch?v=AQf9cZSD5Pc ah now this i can do. Never considered using my tile saw. Now if i can just get the ends off the tube without messing it up. It looks like its just siliconed together.

Well it worked............and then it cracked when i cleaned it up . Its still in one piece but im worried it will shatter over my plants at some point so I just ordered a new one and will live with the tight bends in my pipe.