Re: [ARSCLIST] Repair

[Eric Jacobs <ericj@xxxxxxxxxxxxxxxxxxx>]

I still try to avoid glue altogether.  Getting the glue residue
out of the grooves, trying not to form a "bead" in the groove 
area - these are all unavoidable issues, labor intensive to 
correct and/or work around.  For example, one side might glue
up beautifully, but gravity is pretty hard to avoid, so the
other side may not.  I've taken junk 78s, intentionally broken
them for experimentation on gluing technique, and this has been
my experience.  Note that Krazy Glue (consumer cyanoacrylate
has some issues: (1) the current formulation is more "gel-like"
so it doesn't "wick" properly; (2) the set time is too long; 
(3) if you make a mistake it's truly irreversible (biggest 
liability).  I'm still on the hunt for an industrial anaerobic 
formulation of cyanoacrylate with low surface tension and fast 
setting time to experiment with - I think this might be viable 
in some limited applications.  But again, I avoid glue for the
most part.

Perhaps as important as "tight" is "flat".  Through the use of
precision flat/clear discs made of semiconductor grade acrylic
machined to high tolerances, I create a sandwich that allows me 
to safely transport, clean, play and flip a broken disc without 
gluing it.  I also sometimes use sorbathane mats along the way, 
which have a natural tackiness to them, to hold things together 
without glue.

If anyone is interested in purchasing such discs, feel free to 
contact me off-list.  I get the discs machined in batches in
order to get the cost down since they get machined on expensive
machine tools with special end mills.  The discs are made for
handling broken 16-inch acetates on glass substrates - something
you'd never want to glue, but I can have them made in smaller
sizes if there's enough interest.

Regarding laser turntables, if it won't play with a stylus, it
will not play with a laser turntable.  I've tried every which
way to Sunday, and laser turntables have all the same tracking
issues as a well-designed properly-aligned stylus turntable.
After all, the laser turntable is designed to mimic a stylus.

The primary advantage of a laser turntable is that you may not
hear the pop from the break between the pieces.  If the break 
is bad where the mating edges have been chipped, even slightly,
you will hear the break on the laser turntable as well.

There are tricks to making the break inaudible on a stylus 
transfer.  Choice of cartridge and EQ are critical, giving you
options in post-processing that might not otherwise exist.

With a stylus turntable, where tracking through the break is
problematic (and perhaps impossible on the laser turntable) you
have options for dynamically adjusting the anti-skate and 
vertical tracking force (depending on the townearm) that are
not available with a laser.

The laser turntable works best with clean unchipped breaks on 
discs without warp.  Otherwise a stylus works a bit better in
my experience.  In general, it always requires some 
experimentation as the laser may surprise you one way or the
other.

There are also tricks for getting rid of warp on 78s, but 
that's a whole 'nother thread...

Eric Jacobs

The Audio Archive
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx




-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of Nipper
Sent: Saturday, November 19, 2005 8:37 AM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] Repair


True Steve,

The trick is to get the repair as tight as possible (squeezing all of the
excess glue to the surfaces so that it can be removed by sponging with
water).  It could be better accomplished with some sort of wide clamp or
clamp array instead of the rubber bands.

Martin

----- Original Message ----- 
From: "Steven C. Barr" <stevenc@xxxxxxxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxx>
Sent: Saturday, November 19, 2005 12:29 AM
Subject: Re: [ARSCLIST] Repair


> ----- Original Message ----- 
> From: "Nipper" <nipper@xxxxxxxxxxxxxx>
> > I've had great success with 78s using good old Elmer's glue, a few
rubber
> > bands and a good working knowledge of how a stylus tracks a groove.
It's
> a
> > fairly strong hold yet water soluable so if you make a mistake you can
> > always soak it loose, clean the contact surfaces thoroughly and try
again.
> > On the other hand there are plenty of incompetent Krazy glue formula
> repairs
> > that have been screwed up once and for all.
> >
> From my experience, it is effectively impossible to repair a broken 78
> if the break runs more-or-less "parallel" to the groove at any point.
> The layer of adhesive, although thin, still dislocates the groove path
> at the point of breakage far enough that the stylus doesn't track
> the correct path...remember that the groove is about .003" wide,
> so if the adhesive is more than .001" thick the path is effectively
> half-a-groove out of position.
>
> Steven C. Barr