Have you guys thought about employing a split chuck? Basically just two or three vertical slits of about 5 to 7 mm in length, in an otherwise quite tight fitting holder, with a simple insertable key (or perhaps built-in) to provide just enough rotational torque to spread the needle holder at its slits, allowing the needle to drop out by its own weight.
What do you think? Andy Baron Santa Fe On Feb 13, 2008, at 2:33 PM, Greg Bogantz wrote: > Thatcher, > > That's essentially what I am now doing. The present design is a > press fit of the needle shank into the hole (deep well, actually) in > the needle bar. But the fit must be tight to prevent rattling. > This makes the machining difficult, but more significantly, it makes > the needle exchange difficult because you must use pliers, tweezers, > or some similar tool to hold both the needle bar and the needle > shank for both insertion and removal. Not user-friendly. > Specialized tools and/or jigs could be furnished to make the job > easier, but it's still a tedious task. A friend of mine has > experimented with a similar design. His solution is to glue the > needle shank into the needle bar. That works, but getting the worn > needle out of the needle bar is a b*tch. He gets around this by > using the "semi-permanant" osmium Pfanstiehl needles that were > popular in the 1940s and can last for several playings. I don't > agree with this because these needles are too hard, as I've > commented before, and must be worn in over several playings on junk > records to form their flats. He removes the needle by heating the > glue with a soldering iron to cause it to flow. Still, very tedious. > > Greg Bogantz > > > > ----- Original Message ----- From: "Thatcher Graham" <thatc...@mediaguide.com > > > To: "Antique Phonograph List" <phono-l@oldcrank.org> > Sent: Wednesday, February 13, 2008 3:16 PM > Subject: Re: [Phono-L] threaded needles > > >> >> As an engineer I could not help but to fixate on this "threaded >> needle idea". I agree that threading needles solves the mass issue >> hence the instinctive appeal, but the difficult manufacture is >> equally discouraging. As an alternative, have you considered a sabot? >> >> -Thatcher >> >> >> >> Jon Noring wrote: >>> Greg wrote: >>> >>> >>>> Threading the needle shank and having it screw into the needle >>>> bar is an >>>> option. I hadn't considered that before, but it would pretty >>>> well solve the >>>> extra mass problem. But it would make the needles pretty >>>> involved to manufacture. I'll keep it in mind. >>>> >>> >>> Yes, it would be involved if all the needles are threaded by hand or >>> in small numbers, especially at the diameter being considered. >>> >>> It is intriguing to consider using a very fine threaded rod, if even >>> manufactured in the desired material(s). One would have to grind and >>> polish to create the tip geometry. >>> >>> Which brings up the idea that if a needle is to be especially >>> manufactured, one could consider tipping it with a different >>> material >>> that can be specially shaped (such as spherical or elliptical with >>> no sharp edges at all. It is my understanding that most damage to >>> grooves is due to a tip which is no longer smooth. Maybe the tip >>> could >>> be made from a material of the same hardness as the "grit" used in >>> shellac discs (is it corundum?) to wear down the needle. >>> >>> Just thinking outside the box... >>> >>> Jon >>> >>> _______________________________________________ >>> Phono-L mailing list >>> http://phono-l.oldcrank.org >>> >> >> >> >> _______________________________________________ >> Phono-L mailing list >> http://phono-l.oldcrank.org > > _______________________________________________ > Phono-L mailing list > http://phono-l.oldcrank.org
