How is a stylus manufactured

[w1jim]

I've always wondered but never seen the process - how are the diamonds shaped and then mounted accurately on the cantilever?

 

[bang4buck]

See at 1:08 in this video...

Several other production videos on the Ortofon channel. They're not as secretive as one would think.

 

[w1jim]

Thanks, that’s great and the kind of thing I was looking for. The concept of manufacturing micro components is intriguing.
I have seen SMD electronics assembly line, but these components are almost too tiny to see.

 

[pfcs49]

I'd still like to see how the styli are machined! And how they're held while so doing.

 

[w1jim]

I'd still like to see how the styli are machined! And how they're held while so doing.

I’d imagine they take a larger piece of the stylus material, machine the end and then grind/cut off the “stem”.

 

[pfcs49]

I’d imagine they take a larger piece of the stylus material, machine the end and then grind/cut off the “stem”.

I would too, but how do you get a long skinny shaft of diamond to section and then grind points on?
And how fast can you grind the tip/stylus?
Does it involve more than one time through with finer and finer media to get a micro-polished surface?
And how do they index the stylus so it's flanks are 90* to the cantilever as well as achieving SRA?

As an amateur machinist and engineer, these kinds of problems always fascinated me. I'd love to take a year and spend it observing stuff like this. Machining, fabrication, materials science, petroleum-chemicals-it's all pretty investing stuff.

 

[steerpike2]

And we've had microgroove styli since the 1950s, so it's not new technology.

 

[pfcs49]

And we've had microgroove styli since the 1950s, so it's not new technology.

And my guess is that it may be simpler to grind a Shibata contour than a spherical or truly elliptical point.
Really would like to know!

 

[ripblade]

And my guess is that it may be simpler to grind a Shibata contour than a spherical or truly elliptical point.
Really would like to know!

I believe all styli begin as spherical; the exotic shapes are sculptured into it, adding more complexity and cost. Certainly the elliptical and Shibata are shaped from spherical tips.

I'd like to see the machines they use for this, too. Some kind of elaborate diamond wheel polisher similar to what a jeweller would use to shape diamonds, only smaller and more automated.

 

[w1jim]

I did some patent searching - this gives some more insight.
https://patents.google.com/patent/EP0087020A1

Abstract
A reproducing stylus for a record having a sound groove, said stylus formed by removing front and back portions of its contact area with the sound groove to obtain an edge line portion having an orientation perpendicular to the direction of record travel and the said edge portion is rounded at the corners thereof such that a very small radius of stylus curvature is formed at the tip. The edge line portion is formed by reciprocally moving and grinding the tip on a grinding groove.

 

[ripblade]

^ So even the microridge takes shape starting with spherical.

1. A reproducing stylus for a record having a sound groove, said stylus formed by removing to a predetermined depth front and back portions of its contact area with the sound groove to obtain an edge portion of said predetermined depth having an orientation perpendicular to the direction of record travel where the effective radius of curvature of the stylus at the edge portion is substantially reduced with respect to that at the contact area prior to the removal of the said front and back portions.

 

[arts]

Very interesting read

 

[pfcs49]

Very interesting, but more interesting would be it's actual real world implementation.
I've seen lots of information about record lathes, pressing mills, etc, but how they actually manufacture a stylus seems elusive!

 

[SoundsAlike]

Coils

 

[marcmorin]

https://patents.google.com/patent/US3292936A/en

 

[ripblade]

https://patents.google.com/patent/US3292936A/en

Ouch! Those sharp bottom corners look like they can do serious damage to a record. Is that his so-called "twin tip"?

 

[Nashou66]

I'd still like to see how the styli are machined! And how they're held while so doing.

(a) Top-quality octahedral diamond is used as the raw material.

(b) Diamond powder is used to polish along the crystal axis.

In order to process the tip, the crystal is inserted into a metal rod and carefully polished.

(c) The point can be formed into desired shape, such as round or ellipse.

Afterwards, the crystal is removed from the metal rod and the opposite end is cut down.

 

[pfcs49]

(a) Top-quality octahedral diamond is used as the raw material.

(b) Diamond powder is used to polish along the crystal axis.

In order to process the tip, the crystal is inserted into a metal rod and carefully polished.

(c) The point can be formed into desired shape, such as round or ellipse.

Afterwards, the crystal is removed from the metal rod and the opposite end is cut down.

Boy, that sure is a lot of work!
I can't imagine they do that for the cheaper diamond stylus

 

[marcmorin]

Ouch! Those sharp bottom corners look like they can do serious damage to a record. Is that his so-called "twin tip"?

drawing of the first "eliptical diamond stylus" he did in fact call that a twin-tip. Bi-radial, for all those who didn't want to infringe on a patent name

 

[ripblade]

drawing of the first "eliptical diamond stylus" he did in fact call that a twin-tip. Bi-radial, for all those who didn't want to infringe on a patent name

The 'bi-radials' are a very different cut compared to that patent, as far as patents go. The spherical tip is not truncated as it appears in Grado's patent.

A Shibata also has only 2 cuts but it's also a very different patent.

I don't see any infringement, unless you mean his idea of cutting facets into a spherical stylus.