What do you mean by the CA lifting? It sounds like the wood could be wet, or at least wetter than it should be. Sounds like you have a fix that I woud employ but you may want to figure out why it's lifting. I apply 2 coats of thin to seal and penetrate the wood then start the medium. The 2 thin coats seem to give superior adhesion to the medium CA too.
WB
Concur. Although sometimes I get carried away and apply 4 to 6 coats of thin before switching to medium. I'm curious though. Why is TBC w/o bushings better to prevent this? Also, Why just one blank and not both ( going back to the original post)?
Why is it better? Well you have to realize what causes the lifting:
1. Start with the fact that there is CA on the bushings with the same thickness as on the blank at the point where the bushings meet the blank.
2. Weak CA bond on some types of wood (oily woods), not necessarily green either.
3. Not everyone has surgeon type of hand control - Even cutting a parting ring near the joint of the blank and bushing does not always prevent the "snap" that causes "lifting".
4. The Snap of seperating the bushing from the blank with a weak bond of the blank causes the CA to "lift" and looks a little somewhat a part of a fingernail lifting.
Now, with TBC, there are no bushings for it to stick to. The dead center and live center fit into the tubes with no shoulders, so there is a direct drop off from the blank down to the two centers (hence Turning Between Centers). OF course some CA will get onto these but the breaking point is between the centers and the tubes, not the blanks. The "break" if there is one, is more between the centers and the tubes, than the blank.
In case something is missing for some here - measurements to sizing is done by calipers, not bushings and is FAR more accurate in fitting blanks to nibs, center bands and clip ends.
Why one blank and not both? Between centers live and dead center, you only turn one blank at a time.
To some, it is more time consuming but to me TBC is quicker. I can have a blank on and off the lathe in 2 to 3 seconds without having to rush. I pull a blank off the lathe sometimes 3 to 4 times to inspect it and measure it. ON a mandrel it takes 20 to 30 seconds EACH time you want to take it on and off for inspection. Some people don't do that, but I make lots of segmented pens, and as such I like to inspect them often. When I used mandrels, I would on occasion drop a spacer or a nut (several times over a year) and it would drive me crazy looking for them. With TBC, NEVER a problem because you don't use them. TBC is simple, Mandrels are complicated with many parts and flexing on the mandrel itself. The more parts, the more chances for mistakes, and if you keep score of TBC turners vs mandrel turners in numbers of problems, it is probably 10 to 1 in the number of problems of various kinds for mandrels in posts over the years, including the OP here.
