Revox/DarkLabs hub O ring

[ironbut]

Well, after making a fool out of myself over on the Ampex list I thought I'd throw out an offer here to vindicate myself a little (I thought the poster was looking for some of the O rings but he was actually offering some).

The Revox/DarkLabs hubs have an O ring that is crushed each time you tighten the hub down against the reel. After a while, these get too smashed and/or brittle and the hub adapters don't hold the reel quite as securely. There's a few guys on eBay that have them for just a couple of bucks.
The fellow on the Ampex list found the source for these O rings and instead of the $3-7 that the eBay guys are selling a pair for, they come in a bag of 50 for less than $8.
I'm going to order a bag so any of the Tape Project subscribers that want a pair can just send me a self addressed envelope and I'll send them out gratis, pro bono, comped, in lieu of monetary commiseration,.. free.

I'll post this again when I actually have the rings in hand so please don't contact me regarding these until I do. That is, unless you would also like to order 50 and we can combine our orders (I'll wait a week before I order).

[Ki Choi]

Hey Steve:

It's very nice of you to do so...
I too had just purchased bunch of these aftermaket O rings through my work to feed my Studer hubs and more.
Let me know if anyone wants to know the commercial part number for the O rings.

Ki

[mikel]

regarding these Revox/Darklabs hubs. i sold my dPV Technics a couple of weeks ago to a friend. he purchased a pair of these hubs. i was at his home and attempted to use them. one of them worked fine; but the other Hub did not seem to work correctly. i removed it and something was rattleing inside it. then a small black round plastic plug dropped out. i tried to figure out what they were for and 2 more of these plugs (about 1/2" in diameter and 1/4" thick) dropped out. maybe they were some kind of spacer.

i told my friend to use the stock Technics hubs since if a reel came lose in mid-rewind it would ruin his day. Hubs are something you must really be able to depend on. the stock Technics hubs are pedestrian looking but they seem  to be foolproof.

has anyone had one of these hubs apart? the metal work is pretty but they do look a little 'cheap' inside. i love my stock Studer hubs on my A820 but i'm sure they are not cheap when you can find them. the stock Ampex hubs on the ATR-102 also look and feel quite solid.

[ironbut]

Hey Mike,

Under the O ring are 3 plastic spacers that "help" push the O ring out evenly. If you move the O ring out of it's track the spacers should find a home inside then the O ring holds them in. Each spacer is positioned at the same spot as the top plastic "hold downs". When the hub is loosened, you can hear the spacers rattle and when it's rotated (like when it's locking a reel in place) the spacers shouldn't rattle.

[JoeG]

I have a pair of the Dark Labs hubs for my Technics. I know what you are saying Mike. I too have noticed that one of the hubs works just great, but one of them always gives me fits getting "just right" in order to lock it on the deck. If it doesn't seat correctly on the reel, I get some really nasty wobble. One trick I have been using to make sure it is seated correctly, is to click it into place on the reel, then place the back side (the side facing the deck) against the flat of my palm and give it a firm push with my other hand. That seems to work 90% of the time to do away with the wobble.

[Ki Choi]

In most cases the problem is caused by too much friction between the bottom stationary piece and the movable top piece.  I have fixed the issues in the past by removing the O ring, carefully taken plastic pucks out, and shooting a short blast of lubricant (WD-40) and worked the assembly until it was smooth in turning.

The three plastic pucks extends outward as the cam action from the top piece as it turns - expanding the rubber O ring to make a tight fit to the inner side of the reel.  As the rubber O ring gets old and eventually breaks, the plastic pucks can easily fall out making the hub useless.

Mike, I will bring the different types of Studer hubs available for A820 including the DIN pancake hubs, round pushdown NAB hubs (the best) and the normal wing flange NAB hubs next time when I visit you.

Ki

[ironbut]

In most cases the problem is caused by too much friction between the bottom stationary piece and the movable top piece.  I have fixed the issues in the past by removing the O ring, carefully taken plastic pucks out, and shooting a short blast of lubricant (WD-40) and worked the assembly until it was smooth in turning.

Ki

You can do this without removing the O rings or spacers.
Just lock the hub in the remove reel position and find a spot above the O ring that you can most easily insert the capillary tube on the WD-40. Then twist the hub a little way (which opens more of a gap between the top and bottom pieces) and give it as short a squirt as you can. Then work the hub till it's nice(er) and use a can of compressed air to blow out any excess (you don't want it dripping into your reel hubs or on the reel tables).
When you want to spray the least amount of any spray product like WD-40 an easy trick is to place the can in the refrigerator for a little while. This lowers the internal pressure of the can. I always just leave it in for an hour or so and then test it every once in a while till I get the spray that I want. It's a lot easer if you want to avoid cleaning up the mess that too much product will make.

[Ki Choi]

Good idea, Steve.  I took mine apart before lub job to avoid any WD-40 getting onto the rubber O rings.  However, if one puts as little amount of WD-40 into the gap as possible, it should work without taking the hub apart.

Now, having to explain the WD-40 in the refrigerator to my wife...  On the other hand, she had seen old tapes baking in the oven before.... It's a crazy hobby, indeed...

Ki

[ironbut]

Now, having to explain the WD-40 in the refrigerator to my wife...  On the other hand, she had seen old tapes baking in the oven before.... It's a crazy hobby, indeed...

Ki

I guess being single, you don't think about those kinds of things! It's pretty amusing from where I'm coming from but I could see how it might "rock the boat".
Just don't put it too close to the Cool Whip can!

[darklab]

...The Revox/DarkLabs hubs have an O ring that is crushed each time you tighten the hub down against the reel. After a while, these get too smashed and/or brittle and the hub adapters don't hold the reel quite as securely. There's a few guys on eBay that have them for just a couple of bucks...

Well, in the past ? or better with old O- rings ? there are problems with worn or brittle rings. In the old days the rings was made from rubber, but today a kind of synthetic rubber is used. This material should be more reliable compared with ordinary rubber, says the manufacturer. But who know what will happen in thirty years?

This O- rings are of course not made for the adapters only, but as joints for hydraulic systems. So, if you ever need a replacement ring, ask in an industry supply store, you?ll find them there very probably even cheaper as in any bay. Since the rings are used as joints, which come in contact with oil etc., lubricants like WD40 should do no harm. Those who want to be 100% sure should use Vaseline instead of mineral oil based products.

Inside of the adapters are three curve segments, which push the pucks out to press the ring to the inner diameter of the NAB- hub and lower the upper part to hold the reel. Never try to disassemble the darklab or Revox adapters, they are welded with ultrasound and you never can re- assemble them. For the moment I have no photo ready, but if anybody is interested on a view of the internal he should me send e-mail. fb  at darklab dot de

[ironbut]

Thanks for the info Darklab.
With the number of DIYers here, the warning about taking them apart will certainly be appreciated!

[jeri]

Great information!

Just one quibble with the suggestion to use Vaseline instead of mineral oil as a lubricant.  Vaseline is actually made from mineral oil.  So it will cause deterioration of natural rubber o-rings.  Other elastomers such as Buna-N are resistant to Vaseline, so Vaseline can be used with those if you are sure what material you have.

Jeri

[darklab]

Sure, Jeri, you are right, Vaseline is made from mineral oil.

But you can?t compare this with oils are used as lubricant. I?m not so deep in chemistry, but far as I know the properties of i.e. motor oil or Vaseline depend on the molecular structures. So lubricants contain mostly aromatic hydrocarbons, which are more or less aggressive or toxic. Vaseline, especially the white, on the other hand doesn?t contain such stuff and is neutral against any material.

Most creams and skin- care products, even for babies, are made with Vaseline. If a product doesn?t harm a baby butt, you can be sure it will not attack anything else.   

Frank

[jeri]

Frank,

Natural rubber, SBR, and EPDM elastomers are not resistant to Vaseline (aka petrolatum or petroleum jelly) or to any petroleum product.  They will swell and soften as they absorb petroleum hydrocarbons, including the saturated parafins in Vaseline.  O-rings made of these materials will fail if they are exposed to petroleum products for any length of time.  I know this from general engineering practice and from an unfortunate personal experience when I used Vaseline to lubricate some o-rings in a hose reel even though I knew better.  The normal lubricant for o-rings is a silicone lubricant, although there are a few others.

If you want to use Vaseline (or WD-40) on o-rings, it will be fine so long as the o-rings are made of a resistant elastomer such as Buna-N (inexpensive), Viton, or Kalrez (generally the most chemically resistant, if you can afford them).

But don't take my word for it.  As a test, get some latex gloves and see what happens when exposed to Vaseline.  You may be surprised.

Jeri