Remove the soldering

Discussion in 'General Electronics Chat' started by javiermark, Feb 2, 2008.

  1. javiermark

    Thread Starter New Member

    Feb 2, 2008
    2
    0
    Hi, enjoyed the detailed explanation above on brazing. I have a question going in the reverse direction. How do you unsolder or unbraze a silver-soldered joint between stainless steel and brass without destroying optical components housed within?
     
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    This begs the question, at what temperature can the 'optical components' survive? Obviously, if they're plastic, there isn't a very good way to melt the joint in order for vacuum-based removal. Sometimes, there is an additive that you can apply when it is melted, which brings down the melting point of the alloy.

    If the components can survive the temperature, it is a matter of bringing the entire assembly up in temperature slowly. You do not want to have any significant temperature differential, otherwise there will be uneven displacement, which can crack or permanently damage your assembly.

    If they're very sensitive to heat and you cannot reflow the joint, then it never should have been soldered in the first place. The only other route would be to grind the joint,

    Steve
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,575
    230
    My guess is...you can't. Unless the optical components were designed to be in-place when the brass and stainless steel were silver soldered together and very low melting temp jeweler's silver solder was used, you could not protect them in the reheating process. But, that's just my experience in silver soldering.

    And...what thread were you refering to "above"?

    Ken
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    As the process is going to be somewhat destructive, consider cutting the joint apart. If things are cylindrical, grip part in the chuck of a drill press and use a hacksaw to cut a groove at the joint. You can finish with a small triangular file. Or an abrasive disk in a Dremel tool.

    One alternative to nitric acid (might get you on a watch list) is ferric chloride. It eats stainless very fast, and gives off no poisonous fumes. It will probably do a number on the brass, too. Leaves mega stains in clothes, though.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I believe I'd opt for a diamond abrasive wheel using something like a Dremel moto-tool to cut the item away from the mounting, as it's an easily acquired low-cost method.

    Excessive heat will damage it, vibration due to a coarse method like sawing may cause undue stress, resulting in early failure.

    Were money and time no object, I would cut the thing out using a computer-controlled laser CNC machine. However, both are always an object.
     
  6. arthur92710

    Active Member

    Jun 25, 2007
    307
    1
    One alternative to nitric acid (might get you on a watch list) is ferric chloride. It eats stainless very fast, and gives off no poisonous fumes. It will probably do a number on the brass, too. Leaves mega stains in clothes, though.[/QUOTE]

    Isn't ferric chloride used to etch pcb's? That stuff can eat copper very nicely! You can pickup a bottle at radio shack. you can trow you metal thing into a plastic container pour some juice on it and watch it dissolve! :cool:
     
  7. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Nitric Acid is very nasty stuff, and as mentioned, will get you on a watch list if you are even able to acquire it. It is the basis for nearly all high power explosives.

    steve
     
  8. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Brass is very easy to cut with any old Dremel-type or Fordham-type rotary bit. If it were me, I'd use fine-toothed saw - around 24 tpi. Or a jeweler's file. Jeweler's saws and files are fairly inexpensive.

    The thing was very likely assembled using induction heating, so there would have been no time for the innards to get hot.
     
  9. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    http://books.google.com/books?id=nk...ts=dk_NKx6NSh&sig=DpyF2iGijGYMBOqPLv8GpIbBpmc

    The line at the bottom of the page via an expert. "Nowadays, virtually all explosives are manufactured by processes which use concentrated nitric acid".

    If you visit any bomb-making page, you'll see that one of the most difficult to obtain ingredients is nitric acid, so they have various ways to synthesize it. They admit that you can get your hands on it, but you will most likely be put on a watch list. Don't underestimate your government in it's ability to keep tabs on you.

    Steve
     
  10. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    I guess it's a darn good thing the bomb-making aficionados have never heard of "cold bluing." One ounce bottles are ubiquitous, found in any decent gun shop.
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    How about some more ideas on cracking open Javiermark's stainless steel & brass package to get at those tasty optical components?
     
  12. marina_meggy

    New Member

    Feb 4, 2008
    2
    0
    ..........
     
  13. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    145
    Please forgive my cynicism, but this is your second post with the above link, both of which have spurious ties to question asked in the OP. I will give you option of either explaining the relevance of the links to both questions or ask that you remove the links, otherwise I will remove the links.

    EDIT: I have removed the links until you convince me that this isn't a stealthy advert.

    Dave
     
Loading...