Tension Bands

QIC Tension Band "Drive Belt" Replacement Examples

These belts are made out of Polyurathane, and dry out over time, becoming very brittle. They both loose their elasticity, and causing numerous other problems. Any sign of a loose band should be replaced before reading a tape.

Chuck(G) reports: "The way the tech (who remembered how it was done) at Imation said that they were basically punched out as rings from a sheet of poly, then a special machine would "flip" them and apply them to the cartridge. He thought that the QA lab might still have a manual version of the machine, but he turned up nothing--so it's probably history."

Chuck(G) goes on to clarify: "By "flip" I mean change from an annulus to a cylinder. According to the guy at Imation, it's not possible to do this unaided by a special jig. I don't know if that's true or not, but he was firmly of that opinion."

"Contacts at Imation state that the belts are punched as rings from a flat sheet of PU, then a special machine twists them into their final cylindrical shape and applies them. He tried to find the "manual" version of the belt application tool in their labs, but turned up nothing. You can see this annulus-to-cylinder transition in reverse by taking a fairly fresh belt and boiling it for a few minutes in water--the belt reverts to a ring shape."

To Determine Tension Band "Health", read this message on CCTalk from Al Kossow.

Or better yet, read all 8 messages in the entire thread. It is very enlightening.

A message in this thread also includes a trick on restoring belts that have not completely disintegrated, by using hot water.

But for more "hands-on" demonstration of belt replacement, please watch both of these videos here:

After watching this, my friend Tom suggested: "Keep a supply of chopsticks on hand for things such as this.  The ends could be whittled to smaller diameters or configurations to make safe tools.  Bamboo is a much underutilized material."

These videos were Inspired by Al Kossow on the ClassicCmp List (CCTalk) at

http://bit.ly/1aL5wjD  

Also please see all 8 messages in this ClassicCmp list thread: 3M cart band tension 

The Archive Scorpion manual that I reference can be found here:  http://bit.ly/1eGHmqg

Special thanks to Al at the Computer History Museum in Mountain View CA, for sharing the instructions and experience from which this video is based. 

Choosing Replacement Bands

I have found that, when choosing a replacement band, that the 3M and Imation brands have held up the best over time.  Just choosing a DC6150 tape, even if it has never been opened or used, may not yield a good tension band.  

I have examples where new, unused, unopened DC6150 cartridges branded FUJI and Carlisle had bands that were far worse than the ones that I wanted to replace.  For the purpose of stealing the bands, buying those tapes were a complete waste of money, other than the benefit that I may now warn any of you reading this not to buy those tapes for this purpose.

Here is an example of a good belt (pulled from an Imation DC6150 tape) that has retained its original "flat ring" shape.  I am looking to see if I can get similar Polyurethane sheets, and punch (or even cut with scissors)

I've asked for source ideas at:

http://www.forumjar.com/forums/topic/Thin_Polyurethane_Sheet_source_ideas

Plastibands!

tubastuff 

 • YouTube comment in 2018

A few thoughts, since I believe that I was the culprit who broached the cockeyed scheme to use PBs on cctalk many years ago. 1. Use fresh ones--they degrade with time. If I compare my original box of 4" bands with a new one, the old ones have lost some of their springiness. 2. Don't try to use these in your hotshot high-capacity SLT drive--the speed is simply too great for these things to hold up--they'll end up slipping and tangling. Use an old drive if possible, like the Wangtek one shown in the video. 3. PBs are, in fact strips of PU that are joined/ welded. If you look at one carefully, you can see where the join is. This contributes greatly to the belt not tracking correctly. The best scheme, other than punching annuli from a sheet of PU (which has a bit of lubricant in its formulation), is slicing rings from a length of extruded PU tubing, if such stuff can be found with thin enough walls. I'm still waiting to see the result of that investigation. An awful lot of the original QIC drives have had their drive wheels turn to goo or dry and crack. (Personally, I prefer the dried out ones--the goo is terrible to clean up. Brakleen seems to work wonders there.) There is a solution to this that I've found--and that is to replace the rubber parts with a ring of silicone vacuum tubing stretched over the arbor. Use a bit of Gorilla glue to make sure it sticks. It's very difficult to stretch a hunk of 4mm ID tubing that much, but I find that some silicone lube helps a lot. Trim with a razor blade if necessary. It has enough give and friction that it should last for a couple of decades. But bottom line, I hate the bloody things! Give me 1/2" open reel tape any day.

Alternatives - Mobilion Bands/Latex?Also available from Misumi apparentlyfrom VCFed.org Forum

Boiling Tension Bands to "restore" them

On 8/27/14 2:17 AM, Christian Corti wrote:

> But you can "restore" a worn our belt by applying heat. The best is to pour hot \

> water (70°C should be good enough) and you'll see how the belt shrinks and regains \

> its dark black color. After that, clean the belt (it may have some sticky residues \

> on the surface) and restore it in the cartridge. The shrunk belt has a length of \

> 12-18 cm instead. I've successfully restored many belts with that method.

Wow, that was an interesting experiment.

I had 15 belts, fired up the tea kettle and poured the water into the bands in a \

coffee cup.

As you say, the process throws off a sticky residue, wiped it off and let them dry at \

room temperature. I was able to save 5 of the 15. About half just snapped when I \

tried tensioning them (these are out of carts from the mid-80's) some as you say went \

down to 12cm.

Belt Residue Issues

The residue that the deteriorated belts can leave on the tapes is not only visible, but it can be damaging to the tape media underneath.  

Al Kossow on this topic:  "The 3M cartridge design is broken in that the belt contacts the OXIDE side of the tape and not the backing. As the belt dries out, it binds to the tape binder on the oxide side gluing the binder to the belt. If you are unlucky, the tape wasn't rewound into the BOT/EOT zone and it lifts the binder in the data area. Even if it is in the BOT/EOT zone, you can end up with a situation where so much binder is gone that it confuses the EOT/BOT optical sensors. Neither Chuck nor I have come up with a way to cover the bare area up enough to fool the optical sensors."

If the tape was left in an "un-rewound" position (as it was in the examples pictured above), and just left mid-tape from the last time it was read, or written to, those areas of the tape can be particularly difficult, if not impossible to read.  We are making every effort here to research how to recover the data in these conditions, and will document the painstaking process here on this site.

See our discussion on this topic at Tapeheads.net

Here are 80x magnifications of the tape residue

And here, we've applied Kyread solution to the tape, to show what appears to be the magnetic flux transitions continuing uninterrupted.  But many times attempting to read this tape always errors out in this spot.  We will keep trying!

See our discussion on this topic at Tapeheads.net