Mark,
This video is great. I love the nut-and-bolt trick for assembling the slimlines. And I also think you solved a problem I'd been having with the tip to never press on threads. I'd been having issues where the body finial on my mistrals has not been lining up perfectly with the blank body. I wasn't sure what the issue was--I TBC so it couldn't have been an issue with a warped mandrel. I measured and the thickness of the body was spot-on for the diameter of the finial. And things were lining up perfectly on the section end. I has no idea what was going on because it would always feel like the finial was going on slightly shifted--it would overhang by a fraction of an amount on one side, and underhang by the same fraction on the opposite side.
Well, as many of you know, the mistral finial is two pieces. There's a piece that pushes into the tub and that contains threads on the other end. Then you drop the spring into there, and the actual finial screws on over the spring using the threads. I was putting pressure directly on the threads when I assembled the pen AND THEN screwing on the finial. I think that was my problem, and so far as I can tell one of two things was happening. I think the piece with the threads might have been going in on an ever so slight angle, or I was warping the threads in such a way that the finial was no longer perfectly centered after you screwed it on.
I've since started assembling the finial before pushing it in, so that the pressure is now on the end of the fitting and not on the threads, and they've been perfect every time! I also like the idea of using a spare tube or a nut to avoid putting pressure on the threads and I may try that.
This was super-helpful, Mark. Thank you for posting. And awesome car in your profile pic. '56, right, or is that a '57? I can't quite see enough of the back end to tell.