OldTools Archive

Recent Bios FAQ

6161 Don Berry <berry@c...> 1996‑09‑18 Re: Scary Sharp (tm) WARNING!!
Steve Turadek wrote:

> bottom line: these guys say float-glass is "wavy as hell."  along one axis,
> it's very flat.  along the perpendicular axis, "big" ripples.  'course
> they're talking angstroms.  tens of angstrons actually.  (this was
> enlightening because I thought disk substrate was aluminum, and because I
> thought float-glass was flat.)  they went on to explain there are many
> grades of machined flat glass, including "superpolished" which is flat to 4
> angrstroms.

> just thought you should know ;-)

Just in case anyone missed the smiley at the end of  Steve's post, let me
remind the assembled galoothood that:
 
(1) a human hair is ca. 100 microns thick
(2) there are 1000 nanometers / micron, and 10 Angstroms / nanometer
(3) an average ATOM has a radius of ca. 1-2 Angstroms
(4) silicon carbide paper has no such specs for waviness
(5) a "even" layer of spray-on adhesive is a veritable mountain range
    on this  scale of smoothness.

This isn't to suggest that superfine tolerances of smoothness aren't 
needed in the electronics industry, only that float glass is fine for SS, 
unless you're hoping to plane a diskdrive surface.   ;)

Regards,
-Don Berry



Recent Bios FAQ