[AV Media Matters] Rewinders: when to use

[rohre@arlut.utexas.edu]

Here is my take  on rewinders:

Some for reel to reel instrumentation operate the cleaning and rewinding at
very high speeds and can get out of adjustment and thus damage tapes.  They
must be carefully checked out before use on critical tapes.

They require very great attention to P.M. to keep them operating as intended.
The human tendency is to treat them like the hanger queen transports and
neglect their care, and then try to use them in a crunch.

Some earlier computer drives handle 8mm so poorly with heavy use; (greater
than manufacuturer anticipated duty cycles), that you then need a rewinder to
"condition wind" the tape to a smooth pack for archival storage.  We had such
a program in place when we were making many 8mm archival tapes.  It was a
constant P.M. issue to keep rewinders up to good condition, and we had many
wear out.    Later, we found the original 8mm drive designs only anticipated a
10% duty cycle, rather than 8mm being a one to one replacement for 9 track
reel to reel computer drives. (We needed a much higher duty cycle for our
application.)
At that time, we replaced one or two bad 8mm drives a month, from an 8 hour
computer shift.

If you have good high quality reel to reel uniplanar transports, you may not
need rewinding of tapes after use, to repack them, but older coaxial reel
transports often left tapes in a blocked pack condition, and rewinding of some
means to remove block shift was needed.  Thus rewinding was used as needed,
depending on tape condition after use.

When tapes had been shipped under truck transport in hot southern summer
conditions, we saw need for rewinding some badly packed tapes upon arrival.
Now mostly, these were not new tapes, but tapes that had suffered not only
shipping environments capable of causing cinching, but also, having been
recorded on dubious quality field recorders of various outside contractors, or
agencies.  Often, they were used  tapes before the present recording.

Some government agencies such as NASA use and reuse so many tapes  on as many
as a dozen machines in one launch lab alone,  at Cape Canaveral, for example;
that cleaning and repacking/rewinding services are needed to rescreen used
tapes before the next use.  The idea is to eliminate damaged tapes before
reuse.

What I am trying to express is that differing useage may indicate differing
handling methods for tapes.  Although rewinding smoothly is more often needed
for reel to reel tapes, I have seen many poor packs on VHS and SVHS tape in
heavy or mobile recording use.  I would say you need to monitor the tapes
coming into your facility, or those locally generated, and if you cannot take
down a tape from a copy session and see a good pack upon rewinding it at the
end of the day, first try to correct that particular recorder's winding.  But,
if the recorders are outside your control, and you are tasked with archiving
the tapes, you may need a rewinding and conditioning process, before storage.

Just be aware that more winding and handling can generate as well as fix
problems of block shift, poor packing etc.  There actually are some new tapes
that come off a slitter at manufacture that seem to never behave as normal
tapes do at less than factory pack wheel tensions.  Often we have found in
screening new tape for customers of ours, that such tapes were victims of a
dull slitter blade, worn packing wheels or other out of tolerance conditions
in manufacturing.  Just the things a Quality Control program should and does
catch.  Most new reel to reel tapes today seem to, (thankfully), be of much
better quality than the early days of instrumentation recording.  It is sad in
a way, that just as high quality of reel tapes became the norm, cassette
formats became more popular.  I believe cassette formats will go through, (and
have), the same learning curves to high quality as audio and instrumentation
reel tapes did.

There are now, for example, excellent Broadcast and Master digital SVHS tapes
out there.  However, in the University Department environments, I see many
cheap and inferior VHS tapes being used, because of individuals buying low bid
products.  I believe very high quality is now possible in 8mm,  DAT and
Digital Beta and Beta, etc. tapes.  However, the watch like mechanical systems
of small cassette formats  transports are always going to be more complicated,
and have more to go wrong than the simpler and larger tape drives of
yesterday.  Improved factory quality control often keeps them working well,
but ---there is no free lunch!

Rewinding programs will not replace the need to adequately keep up the
recorders making the masters.  However, having a good rewinding machine is a
good thing, given the need to archive in long term storage, data originating
from many recording sources.

Stuart M. Rohre
ARL:UTX