Hi Greg,
I've read this whole discussion with interest. As I understand it the
goal of this exercise in "mental masturbation" is to reduce the mass of the
reproducer by the weight of the thumb screw. I do not have accurate
measuring tools to weigh a standard thumb screw and don't remember the
weight of your custom aluminum reproducer but emphericly I don't think the
thumbscrew makes up a significant proportion of the total mass which is why
I made the comment about mental masturbation. That being said, I do have a
practical solution to eliminate most of the mass of the thumbscrew. I would
think the majority of the mass of the thumbscrew is in the knurled disk at
the end used for tightening it against the needle. This section and a good
portion of the threaded shaft could be eliminated if you machined a hex or a
flat on the end that is left sticking out of the needle bar after the needle
is inserted and tightened. You would use either a small pair of pliers or a
custom hex wrench to tighten the threaded piece.
RMV
----- Original Message -----
From: "Greg Bogantz" <gbogantz1 at charter.net>
To: "Antique Phonograph List" <phono-l at oldcrank.org>
Sent: Wednesday, February 13, 2008 4:33 PM
Subject: Re: [Phono-L] threaded needles
> 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" <thatcher at mediaguide.com>
> To: "Antique Phonograph List" <phono-l at 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
>>>
>>> _______________________________________________
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>>> http://phono-l.oldcrank.org
>>>
>>
>>
>>
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