I'm sorry to be slow in response to this one: it has been addressed pretty well. But I would like to report that the drill that was in use in the factory in the early '90's, when I was at the damper seminar, was a 3/16" brad-point. I know because I wrote it down and then purchased one reserved for this job at that time. Note that 3/16" is .187", and a #15 is .180". Slightly less clearance for wire. A #13 would be closer, at .185", but the difference is pretty small, what with the variance in cloth that we inevitably encounter. This is all part and parcel of the Steinway philosophy of using side pressure in the guide rail for stability. It allows for variance, particularly in the cloth, and in humidity levels, without sluggish damper wires. After I've prepared the guide rail in whatever fashion seems best, I then try a couple of strips of cloth for fit. I find with Steinways that the thick (.050") cloth seems to be what has been used most of the time. So I have strips of 12-15 mm wide cloth, cut carefully with a rotary cutter and mat and ruler, and I bush a trial hole, burnish it, and try a wire. I think I usually end up with either 13 of 14 mm wide, usually. I would also like to mention that it has been my impression in "matters Steinway" that they will usually use fractional drills unless they really don't work. I don't have any basis for this contention other than my own observations and experience, but it seems to work for me to look for a fractional drill that works first. Exceptions would include things like bridge and key pins, as they require a fairly close "press fit" (I've found about .006" smaller drill often to work well for this press fit), and depend on available wire gauges that are not close to fractional. So then the numbered drills have to come out. FWIW. Doug BTW, thanks all for your sympathies and concern. I am recovering better than I expected, but must wait for mid-July to get out of this wheelchair. Can hardly wait! I've been lucky in a number of ways, and still hope for a "full recovery". On Wed, 23 Jun 2010, Fred Sturm wrote: > On Jun 23, 2010, at 1:32 PM, Jeff Farris wrote: > > Hi List, > > Anyone know what size drill bit to use for drilling new damper wire guide rail holes for a Steinway B? Or where to find out? > > > You can find out by experiment. Start with the diameter of the damper wire, add two times the thickness of the cloth (cloth on either side of the wire), add a bit more for clearance and for the > fact the felt is going to bunch. Drill a hole with a bit that diameter, insert felt, see where you are. Start conservative, so you can just go up a size or two, and you can do your experimenting on > the rail itself. Whatever standard anyone uses is married to the felt thickness. You can vary diameter and vary felt thickness within a range. > Another way to "find out" is to match drill bits to an existing rail and its holes. You can get a good idea just placing the bit against the hole. Or be precise by pushing out the felt and later > replacing it. > Regards, > Fred Sturm > University of New Mexico > fssturm at unm.edu > > > > > > >
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