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  1. #14
    Join Date
    Jan 2008
    Location
    windy city
    Posts
    4,430
    I almost always use soft solder (stay brite #8). (And I deal with systems with 1000's of refrigerant.) As everyone said here, heat evenly and let the heat draw the solder in. A bubbly solder is usually too much heat. For the small sizes you're praticing on, you do not need a flame thrower. Learn to use a smaller 'soft' flame and 'play' with the heat. Do not linger the flame on a particular area for long.
    \m/
    original member of the racoon brotherhood

  2. #15
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,164

    Cool don't or rather more to the point, do sweat it

    Match the heat to the materials-more heat on castings and valves-less on slim tubing.

    Heat the fitting circumferentially and it will heat the tubing enough

    scrub the tubing with either clean emory cloth or mesh; clean wire for female hubs. Periodically clean your brushes! They get loaded with pipe dope, grease, etc. Once the bristles load up with flux, they gunk up with dirt that will contaminate joints.

    Scrub the end of the female hub with emory so the solder sticks to the thin edge for a nicer joint transition.

    Deburr your tubing cuts for better flow; emory will deburr the OD so it fits fully into the hub.

    Watch those heat control pastes, sprays and wet rags. They can cool the pipe if too close. Try to use ceramic fiber blanket instead whenever possible.

    If you overheat a fitting, let it cool down, prep from scratch then be more careful. Don't try to slosh on more flux and pray it seals.

    You can wipe down hot solder with the flux brush or a clean cotton rag dipped in flux. Makes for a nice, professional looking joint without those solder-cicles and stalagtites.

    Make sure there is no tension on the joint just prior to soldering. A joint may seem snug only to loosen as the heat expands the female hub causing the tubing to slip out.

    Clean all flux off externally or it will corrode causing a leak. A mildly soapy rag will clean it and neutralize the acid flux.

    I've seen jobs where the tech polished the copper just before the unveiling to the homeowner--awesome!

    Bend a hook in the end of your solder to facilitate wiping it around the rear of the joint first. As you get around to the front, the hook will be gone leaving you with a straight stick to wipe across the joint and be done.

    If you see a solder-cicle/ stalagtite, flick it off with a backhand motion using your solder stick.

    You can cool a joint with a wet rag but blow on the joint to cool the solder and copper as much as possible with air/ breath first. The thermal shock of a wet rag on a blazing hot copper fitting weakens it.

    Make sure the type of copper is appropriate for the intended use. Size properly.

    Watch for dissemilar metal connections. Use dielectric unions as needed.

    Jet Sweats are your friend.

    HTH,

  3. #16
    Join Date
    Sep 2004
    Location
    Kansas City, Kansas, United States
    Posts
    13,832
    you can not learn this in writing!!!

    there are some links on the net that have video.
    I WILL SELL WORK,GENERATE BUSINESS, GO GET NEW CUSTOMERS!
    YOU SHUT THE HELL UP AND QUIT RUNNING YOUR MOUTH!

  4. #17
    Join Date
    Jul 2010
    Location
    Haw River, NC
    Posts
    30
    Quote Originally Posted by beachtech View Post
    bubbly solder sound like too much heat in my experience
    I meant to get back earlier & say thanks for the advice, but have been busy. I was indeed using too much heat, although I'd have sworn I wasn't. One of the guys in the class with more field experience showed me what he was doing, and he had the torch several inches further from the fittings than I did--I had the brightest blue inner flame cone right on my work.

    A little more practice and I passed my test. Now on to 15%, and then brazing.

  5. #18
    Join Date
    Jul 2010
    Location
    Haw River, NC
    Posts
    30
    I like the transmission-fluid rag to keep the solder from sticking to the tube. I'm pretty sure my instructor would not approve of that particular technique...

    Thanks for the link, the video was otherwise helpful.

  6. #19
    Join Date
    Sep 2010
    Location
    Chicago
    Posts
    218
    We just wrapped up our tubing unit and one thing to remember, when you start brazing don't use too much heat and don't heat the whole pipe (I've seen someone do this), that will cause corrosion scale buildup inside as well as outside in excessive amounts. Is you lab equipped with a oxy-acetylene or an air acetylene unit?

  7. #20
    Join Date
    Oct 2010
    Location
    STL
    Posts
    387
    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...

    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
    -First get the burs out of the end of the tube
    -use emry cloth on the point you will be soldering
    -flux the tubing very important to remember this step helps the solder stick, usually with silver solder I use a liquid flux and for brazing a paste but a paste can work with both
    -Important when heating the spot where the joint will be heat the point or connection that the tube will be sliding into the heat will cause the solder or braze to suck up into the joint sealing it
    -with silver solder remember this little saying when it runs its done(if you heated and fluxed properly)
    -Brazing requires the same principle for heating but you will have to make contact around the whole joint as the rod does not melt quite as fast as the silver solder
    -usually I try to avoid brazing, silver soldering is more simple and faster plus I generally use staybright #8 which is good for up to 14,000 psig I believe which is plenty of strength for most systems.

  8. #21
    Join Date
    Sep 2010
    Location
    Chicago
    Posts
    218
    -usually I try to avoid brazing, silver soldering is more simple and faster plus I generally use staybright #8 which is good for up to 14,000 psig I believe which is plenty of strength for most systems.
    Thanks for the tip on staybright, I prefer soldering for the same reasons.

  9. #22
    Join Date
    Oct 2010
    Location
    STL
    Posts
    387
    Quote Originally Posted by Kaleun494 View Post
    Thanks for the tip on staybright, I prefer soldering for the same reasons.
    Yep just keep in mind when it runs its done and you will have perfect joints, I usually use mapp gas when doing those as well. No need for the oxy/acct unless you want to melt the whole spool of solder lol

  10. #23
    Join Date
    Oct 2010
    Location
    SW Michigan, near Battle Creek
    Posts
    921
    when Im doing demo. It always amazes me what lousy joints have held so well for 25-30-40 years. I guess lousy is as lousy does.

  11. #24
    Join Date
    Jul 2010
    Location
    Haw River, NC
    Posts
    30
    Quote Originally Posted by Kaleun494 View Post
    Is your lab equipped with a oxy-acetylene or an air acetylene unit?
    We use MAPP gas for soldering and oxy/acetylene for brazing.

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