On Mar 15, 2009, at 7:59 AM, Chris Solliday wrote: > you don't need to sand, retaining all material and removing the > indentation > with the liquid swell is sufficient and allows the material to last > longer. OTOH, when working with letoff punchings, it does make sense to sand a bit. The idea being that you want the same amount of material everywhere, and some fibers will have disappeared from the dent or dents. So you want to remove that same amount of fibers from the rest of the surface. When you turn the button, it is likely that a slightly (or dramatically) different area of felt will contact the jack tender. If everything is as even as it can be, you will have more stable regulation. For the wipp cushion, if the dimple is fairly deep, my notion is that there is some additional friction because more surface area of the cushion is contacting the capstan. So a bit of sanding isn't a bad idea (and then iron down the fibers). You don't sand in the middle of the dimple, just the thicker cloth around it. Ideally you replace the cloth when it is at that point. I guess the same would really hold for moderate dimpling. Ideally you have two convex surfaces contacting each other. It doesn't last, whatever you do. But lubrication is more important: prevention rather than cure. For me that means teflon powder on felt, McLube on metal (and polished metal without corrosion or burrs). Both wear and compaction can be reduced by a lot even with extra heavy use. Re-swelling felt is a good method of getting more quality life out of parts, but you get more bang for the buck out of lubrication. Regards, Fred Sturm University of New Mexico fssturm at unm.edu
This PTG archive page provided courtesy of Moy Piano Service, LLC