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Stainless Hardware Lesson

Discussion in 'Electronic Repair' started by Fred McKenzie, Oct 21, 2007.

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  1. I bought a used Hustler stainless steel ball mount with a spring at a
    recent hamfest. I installed it with a stainless steel Quick-Disconnect
    (QD2) screwed into the top of the spring. I found that the spring was
    extremely weak, and suspect it is not the original spring from Hustler.

    I removed the spring and attempted to screw the bottom piece of the QD2
    into the ball mount. It started OK, but wouldn't quite screw all the
    way in. Then when trying to remove it, it came out about half way and
    seized-up. I'm sure it wasn't cross-threaded to begin with, since it
    went in several turns without using the wrench.

    Although it was hard to turn, I persisted until the QD2 started to turn
    more easily. Then I realized that the piece it was screwed into was
    also turning!

    Does anyone have any suggestions on how to undo the seized parts?
    (Penetrating oil and freezing the parts didn't make any difference.)

    Fred
    K4DII
     
  2. Dave

    Dave Guest

    nope, they are probably 'galled'. a condition that happens when you put
    together two unlubricated stainless steel parts. essentially the pressure
    of rubbing has spot welded the pieces together. this condition does not
    respond to penetrating oils and other normal methods since the parts are not
    rusted or dirty.
     
  3. Nick

    Nick Guest


    Unfortunately I would also say this is what has happened - I had the same
    experience with new replacement stainless bolts
    on my bike - great, I thought, fit and forget, except when I was halfway
    through installing the first bolt I had to take it out and it seemed
    unusually stiff. I HAD to get it out so slow extreme force was eventually
    applied even if it stripped things, but it came out - a call to the supplier
    confirmed it must always be used with copperslip grease or similar to stop
    this very problem occurring.

    I think the only solution may be force but very slowly to minimise heat
    causing more spot welds, else it will be a spark eroder or similar drastic
    action

    Nick
     
  4. Congratulations and welcome to galling. What you've done is
    inadvertently scrape off the protective oxide coatings from both
    pieces and welded them together. Next time, try some anti-seize goop
    in the threads. Incidentally, you can have the same galling problem
    with aluminum and titanium.

    You're correct that oil won't do anything useful. However, freezing
    should work. Clean off as much oil as you can remove with some
    solvent. Find someone that has liquid nitrogen. If that's difficult,
    some dry ice. Freeze only the bolt, not the ball mount. A bolt that
    size will take some time to shrink, so you may need to freeze it for
    some time. My guess(tm) is about 2 hours. You could also warm up the
    ball mount end, but it's probably not necessary. When the bolt is
    nice and cold, do the brute force trick again. Don't beat on it with
    a hammer or impact wrench as you're likely to shatter the bolt.

    Another way is simple brute force. Build some custom vice jaws and
    lock the ball mount in place. Flatten the sides of the bolt and
    attack it with a big wrench and "torque amplifier" (steel pipe over
    wrench handle). Beat on it with a hammer if necessary.

    Another alternative is to just leave it as is. It's now a permanent
    part of the ball mount. If it's sticking out too far, cut it back to
    a usable length or install a threaded sleeve between the ball mount
    and QD2 disconnect.
     
  5. PeterD

    PeterD Guest

    This is a relatively common problem with stainless. It will 'friction
    weld' itself easily, and once that happens nothing seems to get it
    apart. I've some interesting stainless bolts and nuts that this has
    happened to, and have seen the effectiveness of the welding being
    higher than the failure point of the bolt!

    What is worse, it is difficult to predict when this will happen, but
    it is important to use a stainless compatible anti-sieze compound on
    stainless hardware.

    I doubt you'll get it apart... If you want I can give you a picture of
    a bolt end with a non-cross threaded nut--the bolt snapped rather than
    the nut coming off (and it took a lot of work to break that bolt!)

    You may have better success drilling it out, if that's an option.
     
  6. Mike Coslo

    Mike Coslo Guest


    When dealing with frozen parts, I use a torch to heat the parts up (if
    they and their nearby parts will stand the abuse. Get 'em good and hot -
    a red glow is not too hot - and back the screw out.

    The obvious disclaimers as to the dangers of this method, such as red hot
    metal burning things, and "Don't try this at home, kids!" apply.

    - 73 de Mike KB3EIA -
     
  7. Heat the ball mount with a torch to cause it to expand and melt some
    candle wax into the threads as a lubricant (watch for fire). I don't
    think you need red hot, just get the mount to expand enough to break the
    bond and apply force to turn the QD threads.

    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
     
  8. Joe & All-

    Thanks for the information and suggestions. I understand stainless is a
    poor conductor of heat. I might try a combination of freezing the parts
    and then using a torch on the outer piece to increase the temperature
    differential.

    The female threads may have been tapped prior to crimping that piece to
    the top shell of the ball, and the crimping process could have distorted
    the threads near the crimp. If I had known about the likelihood of
    "galling", I might have tried re-tapping the threads prior to installing
    the QD.

    Fred
    K4DII
     
  9. Guest

    Hi, Fred.
    Retapping won't help, unless you have an oversized tap. What will help
    is using an adjustable die on the male part and squeezing the die down
    quite a bit before using it. This will give you a less than 50% thread
    engagement, but will still be enough for your antenna. Antisieze
    compound is the real answer. Also, if you ever need to drill and tap
    stainless, use the next larger size drill bit for the tap you are
    going to use. Otherwise you will surely break the tap. I have scars to
    testify to learning that!

    Good luck,
    Paul KD7HB
     
  10. Paul-

    I understand there is also a "thread chaser" tap, which might be
    slightly oversized. I was thinking about the distorted threads being
    cleaned up by re-tapping. Perhaps one of the local hardware stores will
    have a 3/8-24 tap, as well as some anti-seize compound.

    I contacted New-tronics by E-Mail. They also suggested heating the
    female threaded part with a torch. They apparently have encountered the
    problem before, but their instruction sheets never mentioned it or the
    need for an anti-seize compound.

    Also, New-tronics does not sell parts, only complete assemblies!

    Fred
    K4DII
     
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