[AllenAnway]

Thanks for your patience. Starting over, I made a big tapered cylinder of revolution from a line (open ends), I have made both a smaller solid cylinder and a smaller open cylinder of revolution from a line (open ends), I have punctured the larger cylinder with each of the smaller. I have tried every Boolean operation with the large cylinder and every smaller cylinder and get (a) no apparent change but now 3 objects rather than 2 and the big cylinder triangulated or (b) more often, the larger cylinder collapses to be a small remnant of the original. My goal is to puncture a hole through the big cylinder that I can see through and discard the small cylinder. Perhaps I am asking the wrong question of the software? Thanks again for your efforts.