i think we may be over-analyzing a little. perhaps the best thing to do is find a cylinder that is half-gone already (e.g., one with a surface that is severely damaged at one section, but that still has playable parts) and experiment.
but yes, in a perfect world the spirals would be gray and nothing else, and/or the high spots would be evenly high. but that isn't what happens. if you've ever wet-sanded bondo on a car fender there are parallels, in case that helps. and for what it's worth, the flat-knife trick was taught (vehemently) to me by Ron Dethlefson when i was first starting out... Ron L'Herault wrote: > This seems to make a certain sense but I don't understand how/why the > plaster should develop high spots. If the plaster is expanding from > absorbed water, I would think that the rate and amount of expansion > would be fairly equal over its entire inner surface. I.e., all the > plaster would be expanding, reducing the inner diameter equally. What > other factors am I not taking into consideration? Gray spots may just > be the result of the plaster contacting a less polished/more abrasive > area of the nickel. If plating came off from rubbing against the > plaster, the entire surface of the spirals should get gray where they > contact the surface of the mandrel, right? > > Ron L > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On Behalf Of Peter Fraser > Sent: Wednesday, April 26, 2006 10:27 AM > To: Antique Phonograph List > Subject: Re: [Phono-L] best reamers? > > No, actually, the best reamer is no reamer. > > The way to do it is to take a flat-edged table knife and scrape down > the high spots. you can identify the high spots easily by noticing > shiny gray places in the plaster, where the nickel of the mandrel has > compressed and discolored the white plaster when you press the record > onto the mandrel. > > see, scrape, fit, repeat. do it until the record fits far enough to > play. it takes time, but this is why you should do that: > > a reamer gets those high spots, but also sands down the corresponding > opposite spots. you end up with a perfectly round interior diameter, > but one that is usually not concentric with the exterior > diameter...and so the whole record orbits the axis of rotation > eccentrically (that is, the playing surface rises and lowers relative > to the mandrel's surface, with each rotation) and sounds > awful...permanently! > > On Apr 25, 2006, at 6:52 PM, Ron L'Herault wrote: > >> I guess that in order to fit some cylinders onto the mandrel a >> reamer is a >> necessary evil. I believe they can be made differently also. So, >> I'd like >> to know which type of reamer people prefer and why. Since I am >> going to buy >> one, I'd also like to know who sells the type of reamer you prefer. >> >> Thanks, >> >> Ron L >> >> >> _______________________________________________ >> Phono-L mailing list >> [email protected] >> >> Phono-L Archive >> http://phono-l.oldcrank.org/archive/ >> >> Support Phono-L >> http://www.cafepress.com/oldcrank > > _______________________________________________ > Phono-L mailing list > [email protected] > > Phono-L Archive > http://phono-l.oldcrank.org/archive/ > > Support Phono-L > http://www.cafepress.com/oldcrank > > _______________________________________________ > Phono-L mailing list > [email protected] > > Phono-L Archive > http://phono-l.oldcrank.org/archive/ > > Support Phono-L > http://www.cafepress.com/oldcrank >
