Subject: Making holes in magnetic tape

From: "John" <[email-masked]>
Date: Sat Jun 21 18:07:50 2003

Hi,

I have some DC100A type cartridges for my HP-85, but at the start of the
tape the magnetic coating has come away where the drive belt has been left
in contact  with the same part of the tape for too long.

I have figured out the pattern of holes in the end of the tape used by the
optical sensor to detect EOT. I would like to punch a new set of holes away
from the damaged area and see if the rest of the tape is usable.

So any tips please on making suitable holes in the tape, my attempts so far
with a pin have not been a great success.....

Thanks,
John

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From: Joe <[email-masked]>
Date: Sat Jun 21 18:36:00 2003

I would try making a hole with a heated pin or something like that. Or
you might try punching a hole with a piece of small diameter hollow tubing
after sharpening the end of the tubing. Alternatively you might try
blacking out the clear spot with a magic marker or something like that.
That way you could use the original holes. Let me know what you find out.
I'v ehad the same problems and I've been meaning to try some different
things but never got around to it.

   Joe

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From: John Lawson <[email-masked]>
Date: Sat Jun 21 18:53:44 2003

On Sat, 21 Jun 2003, Joe wrote:

 [much snippage] [name of original poster not known]

> >with a pin have not been a great success.....

   Back in my Film Biz days, we used to do "spot editing" on magnetic tape
by scratching away the oxide with a razor blade or Exacto knife...  if you
were careful, you might be able to make the 'holes' that way, and the tape
strength wouldn't be compromised, either. Maybe even very fine sandpaper
or crocus cloth n the end of a Q-tip might work to get the oxide cleaned
off, leaving a nice clear spot for the sensors.

  Just my 200 millidollars..

  Cheers

John

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From: Don Maslin <[email-masked]>
Date: Sat Jun 21 19:22:00 2003

> things but never got around to it.

The possible problem that I see with the heated pin is the
likelihood of leaving a raised 'donut' from melting the mylar that
could interfere with proper spooling of the tape.

						- don

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From: Joe <[email-masked]>
Date: Sat Jun 21 19:51:00 2003

>could interfere with proper spooling of the tape.

   There's only one way to find out!

    Joe

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From: Brian Chase <[email-masked]>
Date: Sat Jun 21 19:58:00 2003

> > So any tips please on making suitable holes in the tape, my attempts
> > so far with a pin have not been a great success.....

>   I would try making a hole with a heated pin or something like that.
> Or you might try punching a hole with a piece of small diameter hollow
> tubing after sharpening the end of the tubing. Alternatively you might
> try blacking out the clear spot with a magic marker or something like
> that. That way you could use the original holes. Let me know what you
> find out. I'v ehad the same problems and I've been meaning to try some
> different things but never got around to it.

What's the diameter of holes being talked about?  I think the hollow
tube approach is a good one, if you can find a small enough diameter
tube.  Another approach might be to use a solid rod with a flat head.
Ideally, I think you'd want the end of the rod to have a slightly
concave surface like that of a three-ring-binder hole punch, but a flat
surface might work if the edges are sharp and the applied "thwack" is
very swift.

-brian.

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From: Joe <[email-masked]>
Date: Sat Jun 21 21:46:00 2003

At 05:53 PM 6/21/03 -0700, you wrote:
>tube. 

   The holes are about 1/16" IIRC. Check the hobby shops, they used to
carry many sizes of brass tubing. Brass is soft and wouldn't last long but
it should last long enough to fix a good number of tapes. You might also be
able to use a large size hypoderic needle but the end of them is cut at
angle so you'd have to cut the end of to make it square and then sharpen
it. I think the needles are stainless steel so they'd hold up longer but
they'd be harder to sharpen.

> Another approach might be to use a solid rod with a flat head.

   You could do that but only if you have an outer piece (a die) with a
close fitting hole for the punch rod to go into. Otherwise the tape would
simple bunch up around the punch. Die making is a real ART. Not only do
they have to be a very close fit but you'd also have to have something to
guide the punch to make sure that it went into the hole in the die without
hitting the die. All in all I think it would be a lot easier to sharpen the
end of a hollow tube and use it on a piece semi-hard material (wood) like a
cookie cutter.

   Joe

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From: [email-masked] (Tony Duell)
Date: Sun Jun 22 12:42:00 2003

> in contact  with the same part of the tape for too long.

A very common problem :-(

> with a pin have not been a great success.....

Have you thought about making a die of some kind (possbly a folded piece 
of brass) with the holes in the right place. Slip the tape in that, clamp 
it up, then put a punch through the holes. 

A pin is the wrong shape -- you want a flat-ended (or slightly concave) 
punch. To guide it and keep it vertical  I'd use a watchmakers staking set, 
but I guess few people have one of those here.

-tony

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From: [email-masked] (Tony Duell)
Date: Sun Jun 22 12:44:06 2003

> blacking out the clear spot with a magic marker or something like that.

That trick often works for reading damaged tapes (I recovered some 82176s 
(for the 82161) that way), but the magic marker doesn't last. I think I 
got about 10 passes before I had to go over it again.

-tony

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From: Kevin Handy <[email-masked]>
Date: Sun Jun 22 13:46:00 2003

>surface might work if the edges are sharp and the applied "thwack" is
Check with a arts & crafts store. They often have paper punches for doing
ornamental paper work, and some of them make very small holes. It
depends on what diameter you need.