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  1. #1
    Join Date
    Jul 2010
    Location
    Haw River, NC
    Posts
    30

    Soldering advice

    Probably not the best forum for this post, but I'm not eligible for access to the 'pro' section yet...

    I'm about halfway through my local community college's first HVAC/R course, and we're practicing soldering. I've done plumbing work for years and thought I'd be pretty good, but I'm having a hard time (then again, I don't remember anyone ripping my solder joints apart before and critiquing them, so maybe I was never as good as I thought).

    I seem to have two major problems. The first is using just a little too much solder, especially on the 1/4" tube, but really all the way up to 1/2"--do any of you old hands have any guidelines on how to tell when it's enough without over-doing it?

    My second problem is with bare spots on the copper, where the solder doesn't stick. It's got to be hot enough--it's surrounded by good coverage, so I'm thinking that there's oil or something on the copper. We're cleaning the tube with emery cloth, but I wonder if I'm getting oil or some other contaminant from my skin onto the copper while I'm cutting and swaging it. They're short (2") pieces, so it's tough to completely avoid handling it. Any other advice here?

    Is there any flux/solder/refrigerant safe solvent that can be used to clean oil, etc., off the tube before sanding it?

    We're using Stay-Brite 8 and a paste flux from Harris.

    Thanks,
    Heath

  2. #2
    Join Date
    Apr 2004
    Location
    Bartlett, IL
    Posts
    6,619
    In the last 15 years I don't ever remember soldering 1/4". I don't solder refer lines either, it's all brazing for me. The only copper I solder is for boilers and water heaters. Every joint gets cleaned with emery cloth then I clean it with flux, once the flux starts to boil I give the joint a couple sweeps of solder and clean it up with a wet rag when needed.

  3. #3
    Join Date
    Feb 2008
    Location
    Waffleville
    Posts
    10,339
    Quote Originally Posted by htroberts View Post
    Probably not the best forum for this post, but I'm not eligible for access to the 'pro' section yet...
    get your post count up to 15 and apply for promembership. Best thing you can do for yourself, especially starting out

    i prefer sil foss 15% and a hot torch. be aware, there is a difference in soldering, and brazing. When brazing, not much attention to cleanliness and sanding is needed. The heat will take care of all that for you. Generally when brazing and soldering you work your heat around the joint to achieve an even tempurature all around it. This will happen very fast on small lines, such at 3/8's (which am assuming that's what you're calling 1/4) feed your material in from opposite side of the heat, and the material will suck (if you sill) to the heat. Is a practice to be perfect type of skill, since you're in trade school, practice as often as you can till you're comfortable. Vertical up is the most challenging joint for many people, and one of the most common in the field, i would also get good experience in brazing at different angles and in different scenarios, such as tight, difficult, access.
    If Guns Kill People, Do Pencils Misspell Words?

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  4. #4
    Join Date
    Jul 2010
    Location
    Haw River, NC
    Posts
    30
    Quote Originally Posted by beachtech View Post
    get your post count up to 15 and apply for promembership. Best thing you can do for yourself, especially starting out
    I'm working on it, but I don't want to make a bunch of nonsense posts just to get to fifteen.

    i prefer sil foss 15% and a hot torch. be aware, there is a difference in soldering, and brazing. When brazing, not much attention to cleanliness and sanding is needed. The heat will take care of all that for you. Generally when brazing and soldering you work your heat around the joint to achieve an even tempurature all around it. This will happen very fast on small lines, such at 3/8's (which am assuming that's what you're calling 1/4) feed your material in from opposite side of the heat, and the material will suck (if you sill) to the heat. Is a practice to be perfect type of skill, since you're in trade school, practice as often as you can till you're comfortable. Vertical up is the most challenging joint for many people, and one of the most common in the field, i would also get good experience in brazing at different angles and in different scenarios, such as tight, difficult, access.
    No, I mean 1/4" O.D. copper. We're soldering 1/4, 5/16, and 3/8 right now and will move on to larger sizes, and then later, brazing. So all the brazing advice, while interesting and possibly more practical for the real world, is not helpful for my class, at least not yet.

    I typically pre-heat one side for a few seconds, move the torch to the opposite side, and touch the solder to the joint on the first side, pulling the flame away from the joint. Like I said earlier, my two problems seem to be getting enough solder without too much, and having these 'bubbles', which I attribute to either not having enough heat, which seems unlikely, or having some sort of contamination on the copper.

  5. #5
    Join Date
    Feb 2008
    Location
    Waffleville
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    10,339
    Quote Originally Posted by htroberts View Post
    I'm working on it, but I don't want to make a bunch of nonsense posts just to get to fifteen.
    why not? start a new thread introducing yourself as the new guy on the block. you'll get to 15 in no time

    bubbly solder sound like too much heat in my experience i generally don't take my flame off the joint unless i am getting too hot. the technic for both is the same, except as i was saying, you don't have to spend as much time in prep for brazing. if the pipe is oily, you can burn it off with your torch followed by sanding and applying flux to it getting it ready to solder.
    If Guns Kill People, Do Pencils Misspell Words?

    http://www.youtube.com/watch?v=An2a1...eature=related

    Before we work on artificial intelligence why don't we do something about natural stupidity?

  6. #6
    Join Date
    Jul 2010
    Location
    Haw River, NC
    Posts
    30
    Quote Originally Posted by beachtech View Post
    why not? start a new thread introducing yourself as the new guy on the block. you'll get to 15 in no time

    bubbly solder sound like too much heat in my experience i generally don't take my flame off the joint unless i am getting too hot. the technic for both is the same, except as i was saying, you don't have to spend as much time in prep for brazing. if the pipe is oily, you can burn it off with your torch followed by sanding and applying flux to it getting it ready to solder.
    Thanks.

    BTW, I like your signature quotes... and where'd you get the cutaway compressor illustration? I need a picture for the cover of my notebook. I was going to ask the girl () with the Canadian flags the same question, but I probably couldn't turn that one in.

  7. #7
    Join Date
    Dec 2002
    Location
    Tampa, Florida
    Posts
    706

    use your flux...

    After applying solder to the heated joint, use your flux brush with flux still on it & "wipe" around the soldered joint. You will end up with a solid connection that looks great. Another thing to look at is your solder itself, on more than one occassion I have had to use some sand cloth on the solder because where I had it stored, oil or other contaminants got on it.

  8. #8
    Join Date
    May 2008
    Location
    United States
    Posts
    64
    I wish I could give you sage advice from years of soldering, but like most of the guys here I braze all the time. I certainly remember having to go through that soldering stage at the apprentice school (many moons ago) before getting to brazing, and I had those holidays (those spots without solder) too at first when the joints were busted apart.

    First off, make sure you're heating the fitting. Watch your flux; it reacts differently at different temperatures and gives you a visible sign of when to start feeding the solder. Watch what part of the torch flame you are hitting the joint with -- the tip of the inner cone is the hottest part of the flame, and it doesn't take much heat on such a small OD joint (i.e. try holding the torch farther from the joint than you would a 3/4" water pipe so that it doesn't heat up so quickly). Heat your joint evenly; don't loiter on one spot. Feed your solder in from the opposite side of the flame; if you've done everything right, then the capillary action will draw the molten solder around the joint toward the flame -- doubly so on such small tubing.

    All in all, the best advice from above was "practice makes perfect." You just have to practice. A lot. It might be easier for you if you practice on a larger OD tubing on your own. Since you've been doing plumbing work for a while, maybe practicing on some 3/4" and busting it apart can help. I'm going to say I think beachtech's correct -- I think you're putting too much heat on it. Work on making a good joint, then work on making it "pretty". You'll get through it, and you'll be on to brazing soon enough. Pay good attention when you get to that; brazing is a crucial skill in our field. You can just ask the three pipefitters that were fired this past week from my company. I get to go pull in some OT tomorrow repairing all the joints of theirs that failed on several new installs and cost them their jobs.

  9. #9
    Join Date
    Mar 2006
    Location
    DFW
    Posts
    3,967

  10. #10
    Join Date
    Oct 2004
    Location
    The Zone
    Posts
    392
    When newbies are learning i have them lay the 15% silfloss against the joint till it starts to melt. Then once it does work your way around the joint, once that is done I put the heat around the back part of the fitting to move the silvfloss back into the joint. and capp of if a lot got into it. The key is this has go very quickly, forget the turbotorch of you be changing out a lot of txv's and schraders (pull them). The oxy/acty needs to be hot enough to make it happen....and use nitrogen. Keep a wet rag handy, and around what you do not want to get hot.
    It's Hammer Time!

  11. #11
    Join Date
    Dec 2004
    Location
    Grand Rapids, MI
    Posts
    618
    soldering - heat the joint, not too much, use the flux brush, also I've been told the length of solder used equals the diameter. ie: 1/2 dia means use just a 1/2 length of solder. pre-bend the solder so you don't use so much.
    luck dan

  12. #12
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,583
    1) Clean the male portion with open weave cut cloth. I use Diversitech Grip Cut.

    2) Female fittings should get a fitting brush cleaning.

    3) Flux, beyond the area where you expect solder to end up.

    4) Heat to melting point, heat draws solder into the fitting.

    4a) Wipe the joint with a damp rag.

    5) More practice.
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  13. #13
    Join Date
    Oct 2009
    Location
    new jersey
    Posts
    246
    I always braze. Stay brite is for rotor lock valves which are alloy. They can't take the heat of brazing.

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