On Dec 17, 2008, at 12:40 PM, David Skolnik wrote: > Sorry to be unclear on that point. I was suggesting using the > smaller pin only for sizing the bushing. When dry, you would use > the appropriate sized pin for the birdseye and adjust the bushing > accordingly. It just might need less such adjusting than if there > were no sizing pin used at all. Also, to the extent that there is > concern about glue failing, the (small) pin might still function as > a clamp, once the bushing has swollen. It's still not a spray'n-go > fix. if you are applying a wetting agent to "re-swell" the action center felt with parts unpinned, a sizing pin about a size smaller than the target is a very good idea. Actually, if you unpin the parts there are a couple other ways to re-tighten the center: one is just to leave the flange unpinned for a couple days, The felt relaxes, and the fit is tighter when it is reassembled. And you can mechanically fluff the felt with a needle. I use a #12, the very finest I can find (sold as quilting needles), and insert it 5 or 6 places around the circumference. How permanent this is can be debated. If you had enough felt fibers in place, but simply over eased a bit by excess burnishing or by too much wetting agent, it seems to me likely that these might be good and relatively permanent methods. But personally I wouldn't use anything with as high a water content as Profelt on action centers. Key bushings, wipp cushions, letoff buttons, dampers, any number of other things, but not action centers. Too aggressive by far. 50/50 alcohol/ water is too aggressive for me, though I did use it once on a Samick action, on instructions from tech support (warrantee work, they were paying), followed by heat to speed dry. And it worked okay. I think it's a good idea to keep in mind the way action center bushings are done in the parts factory. Essentially they are felted in place, to a very high density. Dense felt is used to begin with, but when it is inserted in the hole, the fibers are disturbed a lot. The outer ones are stretched apart, and the inner ones are squished so that they press into the middle, and what you have is a spongy mess compared to what you need. So they insert a sizing pin (I think about 1 size smaller than the target), and apply a wetting solution. WHen it is dry, they remove the sizing pin, some do a burnishing step, and then the parts are pinned together, and the bushing is wetted again. The wetting agent is simply water, with some vehicle to help it penetrate the felt, and to control the percentage of water. THe water is absorbed to some extent by the wool fibers, which swell. Since there is a pin and a wood circumference constraining the felt, the fibers press against each other more, and they presumably shift a bit to become more uniform in layout. At the same time, the water causes the scales on the fibers to raise, so that the fibers become more interlocked. When it dries, the fibers shrink back to their original size individually, but they are locked into a somewhat different and more dense pattern. If too much water was used, they will shrink beyond what was aimed at, away from the pin, leaving a gap. This is very touchy stuff, where we are talking about less than .001" being significant. So the precise formula of water is very important. I don't know what the factories use originally, but most people talking about applying a wetting solution for easing tight bushings talk in terms of 10:1 alcohol: water or thereabouts, at least as the first step. Profelt is way more water than that. Regards, Fred Sturm University of New Mexico fssturm at unm.edu
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