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Rubber idler wheel rubber restoration

Discussion in 'Electronic Repair' started by Jeff Liebermann, Jan 12, 2008.

  1. I've been volunteered to resurrect a Gerard A75 turntable and a Sony
    250 reel to reel tape deck.

    Both the turntable and tape recorder have rubber idler wheels that
    have turned hard as a rock. Is it possible to soften the rubber with
    some chemical?

    In the 1960's I would just replace the rubber parts, so this was not
    an issue. Now, I have to work with what's in front of me. Worse, I
    have one shot to get it right and can't really risk a failed
    experiment.

    I've applied No-Slip goop to the outside of the idlers, which works
    for a few hours and then starts to slip. That's not going to work.

    I also have a bottle of foul smelling Methyl Prapasol Acetate, which I
    use to clean and soften rubber parts in laser printers. It works well
    for printers. However, my experience with the stuff on really old
    rubber parts (over about 10-15 years) is that the rubber just
    crumbles. I don't want to risk it.

    Duz anyone have a better potion, elixer, process, or incantation for
    softening rubber idler wheels?
     
  2. Sjouke Burry

    Sjouke Burry Guest

    Take out the wheels, put new rubber on them, freeze them with
    liquid nitrogen,or CO2 liquid spray, then machine the cold,
    hard rubber to the proper dimensions.
    You might have to re-cool occasionally.
    I dont think you can apply some magic to the old,almost crumbling stuff.
     
  3. N Cook

    N Cook Guest


    A better description ,dimensions etc would help.
    If they are the thin metal discs with rubber at the periphery of the rim
    and returning over the disc, both sides, a few mm, then I have a fudge for
    those.
    Otherwise O rings are useful, don't usaually need to be flat , to work
     
  4. radiosrfun

    radiosrfun Guest

    I'm not sure if anything here would help - but I believe - MCM Electronics
    sells a kit of some sort. Check with them.
    They do have a web site - maybe you can go there to look up the "keyword".
     
  5. Google "rubber rejuvenator". There are a lot of products.

    I've used Fedron (from Federal Mining and Manufacturing) successfully.
     
  6. From the description, it doesn't sound like a rejuvenator will help.

    Some photos would help to determine if an off-the-shelf rubber
    tire, belt, or O-ring could be pressed into service here.

    Also, isn't/wasn't there a place that would rebuild your rubber parts
    on a custom basis?

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  7. Fedron will restore "hard as a rock" (the OP's description) rubber. Whether
    it's the appropriate product for this particular purpose is not clear.
     

  8. Try Old rubber is a common problem, and
    several people there rebuild rubber drives.

    http://groups.google.com/group/rec.antiques.radio+phono?hl=en for google
    group users.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     

  9. Are you thinking of PRB? They are long gone. What little is left is
    now part of Russell Industries. http://www.russellind.com

    They have a downloadable cross reference for availaible parts at:
    http://www.russellind.com/prbline/licensing_agreement.htm I haven't
    installed it, but I will compare it to the old printed version I have on
    hand.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  10. Guest

  11. DJM

    DJM Guest

    Try xyol (xylene) the paint thinner. I was told by a Xerox repairman they
    used it on copier rollers when they got hard.

    I have used it and works for me.

    Dave
     
  12. James Sweet

    James Sweet Guest

    Zippo lighter fluid apparently works too, my friend soaks hardened rubber
    parts in it. When they get really bad there's not much you can do other than
    replace them though.
     
  13. Mr. Land

    Mr. Land Guest

    Are they "slippery" hard or "brittle" hard? Can you see any cracks
    on the drive surfaces? If they are brittle hard w/ major cracking
    (i.e. cracks that run into the rubber below the drive surfaces) I
    would
    be surprised if you could find any chemical that will help.

    If they're not that bad, I've had good luck with GC Electronics
    Rubber Rejuvenator.

    For really, really hardened rubber I've had success with
    Teac Rubber Cleaner (Part No. RC-2). This a potent,
    oily liquid that smells like liquid moth balls. I found a
    discussion thread that indicates it is no longer made,
    but it looks like Rawn makes a close replacement:

    "...
    I've used the old TEAC rubber conditioner since about 1979 and I still
    have about 1/2 oz left of an old 2 oz glass bottle. That's how far it
    goes when used in moderation. That was my favorite for pinch rollers.
    The bad news is TEAC doesn't sell it anymore. The good news is it was
    made for TEAC by Rawn and they still sell the latest incarnation as
    "Re-Grip" They changed the formula a couple times because someone in
    California found some chemical in it to be carcinogenic. But none of
    my tape decks have gotten cancer, so I guess the joke's on
    California.

    http://www.aedwis.com/rawn.html

    ...."

    I still have a mostly-full 7 oz can of the Teac cleaner from 20 yrs.
    ago. Guess I'll keep the cap on it...
     
  14. Slippery hard. I spun both idlers while burnishing with fine emery
    cloth to roughen the surface. That's helped, but without the
    compression provided by the normally springy rubber, the turntable and
    tape recorder both still slipped. Also, no flat spots.

    The idler in the Gerrard turntable looks like the top row, 2nd from
    right:
    No cracks. It's not like they're ready to crumble or fall apart. The
    rubber is intact, but hard as a rock. I didn't photograph the idlers
    but can do so when I return to the scene of the crime, er... customer,
    because there's no obvious damage. Just a hardening of the rubber.

    Others have suggested machining it down and adding a layer of new
    rubber from a belt or rubber sheet. I've done that in the past and it
    works. It might work with the Sony idler, which is quite wide.
    However, the Gerrard turntable idler is only about 2mm wide at the
    point of contact, and will therefore be difficult to resurface.
    Well, I may be lucky here as there is no obvious cracking. However, I
    suspect if I bend the rubber sufficiently, it will crack instead of
    stretch.
    I've tried the stuff in the past. Like the other rubber cleaners,
    rejuvenators, restorers, and recovery compounds, it softens only
    surface of the rubber. My guess(tm) is about 0.3mm deep at most. The
    rubber is not porous so the solvent only affects the surface. What
    I'm looking for is something that has a sufficiently small molecular
    diameter to penetrate deeper than just the surface.
    Sounds interesting. I'll see if I can find some. Moth ball stench
    would be a naphthalene. That can probably be found at the hardware
    store.
    I'll probably order some tomorrow.
    <http://www.longselectronics.com/product.jsp?path=-1|12565&id=1194>
    <http://www.mcminone.com/product.asp?product_id=20-230&catalog_name=MCMProducts>

    I just found a box of ancient idlers and belts to practice on. I've
    got about a week to tinker before attacking the antiques.
     
  15. N Cook

    N Cook Guest

    When you've failed with the gooey stuff.
    This is what I've done for a Beogram idler.
    I assume from the pics you directed to , that it is based on a thin metal
    disc.
    I cut a strip of moped inner tube, left the original ribber moulding in
    place just in case my fudge did not work, seriously stretched the moped
    rubber over the pulley rim and glued in place.
    There was axial room to allow for the greater thickness and adjusted for the
    change in "gear ratio" at the adjuster cone mechanism
     
  16. Yeah, that was probably it. I think someone else suggested another place
    that has a similar service.

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  17. Mike S.

    Mike S. Guest

    Yep.

    TEAC used to sell a rubber rejuvenator for cassette decks that was
    essentially xylene. A suitable substitute can be bought in the US as a
    paint/gunk remover called "goof off" in the yellow metal can.
     
  18. Ken Layton

    Ken Layton Guest

  19. John

    John Guest

    I have had some success by boiling idlers and belts in water for a few
    minuets
    Costs nothing to drop an idler in a pan of water, give it a try.
    Cheers John.
     
  20. That looks like a page out of their mid '70s paper catalog. How did
    you find it? Most of the links of the Russell website are dead, and
    most good pages are dated 2002.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
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