Silver Solder Slip Up!

Discussion in 'Clock Repair' started by ChrisCam, Jan 15, 2020.

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  1. ChrisCam

    ChrisCam Registered User
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    Hi,
    My first attempt at silver soldering was both a total failure and in its own way a success. Using 2 small butane torches and easy flow solder nothing stuck and the only thing that got too hot was my hand.

    I used borax solder and cleaned all necessary parts well.

    So where did I go wrong:
    Easy now I have reflected, the heat was focused only on the joint. The brass being joined was held on one end in a large metal bench vise and a helping hand on the other. So massive heat sink here and with butane just capable of lifting the temperature a bit above the solders melting point it never got there due to heat dissipation.
    Using Borax also not too bright as I needed a longer lasting flux.

    So my question is how do you hold together the parts without holding them in metal.

    I am also minded to look at oxy / propane which will offer more localised and rapid performance and I have hopefully found a UK supplier of a less costly alternative to the Smith Little torch which I hope may acheive the same results at theweldingwarehouse.

    Chris
     
  2. David S

    David S Registered User
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    #2 David S, Jan 15, 2020
    Last edited: Jan 15, 2020
    Chris,

    To reduce the heat sink effect I use a solder block from a jewellery supply place. There are a few types, but the one I selected is full of holes which allows me to use thin pieces of wire through the holes to secure parts. Or as in the supplied picture I have a spring wire (aka formed coat hanger) in my bench vise holding two parts together.

    fixtured for joining.jpg
    And here is an example of the two parts held by wire "staples"
    nail heads silver brazed fixtured.jpg

    I also have a thin fire brick that I rest this on when I use a lot of heat. The fire brick itself acted too much like a heat sink.

    David
     
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  3. ChrisCam

    ChrisCam Registered User
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    Hi David, I think I was thinking too hard and missed the obvious. Thanks for that. Your honest view of the Smith little Torch do you have oxy / acetylene or propane and what flux do you use?

    chris
     
  4. David S

    David S Registered User
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    I have a Smith torch "clone" that I got along time ago. When I use it, it has done what I want. The consumer oxygen tanks are quite expensive for what you get. However I can usually silver braze with my butane torches. We have a member here that only recommends USA made Smiths little torch.

    As for flux I use a borax based flux for silver brazing. I have seen others use a high temperature flux that is black or dark grey in color, usually with much larger torches, but can't comment.

    David
     
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  5. ChrisCam

    ChrisCam Registered User
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    Thanks David,
    The Smiths Little Torch if genuine is good no argument based on what I have read but you have to weigh up the times you have a credible repair alternative in terms of not soldering etc.
    Where silver solder and the Smith torch comes in is when silver soldering a large piece.
    How often does a repairman really have to silver solder....few going by the posts. Let's take a split on a plate, you could instead rivet a plate over it. However how many times would using silver solder do a better job than soft.....that is a debate that will continue.
    I think it a fair point also that recommending the Little Smith Torch does not mean another alternative would not be OK just means in effect spending less comes with a risk as not tested, known or proven.

    Chris
     
  6. David S

    David S Registered User
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    Besides the strength of silver solder, it is also desirable by some to make a more invisible repair since it is such a good color match to brass.

    David.
     
  7. gmorse

    gmorse Registered User
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    Hi Chris,

    This is part of the problem; once you have the work set up on an insulating base, heat the whole area, gently at first so as to fuse the flux without blowing away the solder chips you've set over the joint, then open up the torch until the solder just runs into the joint.

    Regards,

    Graham
     
  8. Willie X

    Willie X Registered User

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    Your asking for trouble to use high temps on brass parts. Soft solder and a good tight fitting joining is good and much less riskey. Willie X
     
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  9. Jerry Kieffer

    Jerry Kieffer Registered User
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    The cost of tools is always a fascinating subject.

    Personally, my most expensive, versatile and highest quality tools used in horological repair have paid for themselves many times over unlike my inexpensive lesser quality tools. In fact, the most expensive have actually paid for themselves in a single job on occasions that includes my Smith little torch.

    In most cases, quality tools need to be experienced to be understood and while this also holds true with the Smith little torch, its features are more easily explained and understood.

    First, orifice tips are as small as .003" up to about .030" and are jeweled. The clones are whatever they are and unjeweled so that each time they are cleaned, sizes often change. In the Smiths case, the flame sizes are absolutely the same each time they are used and previous skills are improved with each use. While the jeweled orifices are part of the consistency, regulator regulation can also be set identical with each use and trusted to maintain and hold exact settings unlike the clone regulators from china. This consistency allows me to select a tip and regulation that will provide the heat needed to complete soldering or welding in a few seconds. This in turn limits heat to the immediate area of the joint making high temp silver soldering very safe even for a beginner with minimal instruction. If purchased at a welding supply shop, advise and instruction is often available.

    When soldering regardless of the type, heat is often applied to a wide area around the joint for periods of time required to melt what is being used. However if quality work is your goal, there is no substitute for absolute control of required heat to complete the job in a few seconds without effecting surrounding areas no matter how small.

    No matter what one is told, sooner or later you will figure out there is no free lunch.

    Jerry Kieffer
     
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  10. ChrisCam

    ChrisCam Registered User
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    Great point David
    Chris
     
  11. ChrisCam

    ChrisCam Registered User
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    Yes your right Jerry, I was being a tight arse so thanks for the post to make me think again, just hope the oxy / propane will suffice, might get an oxy / con in place of the tank.
    Chris
     
  12. shutterbug

    shutterbug Moderator
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    When you have the tools and ability to hard solder, you will find yourself using it more often. I've been able to save two heavy pendulums that the adjusting assembly had broken off from. A good strong bond that won't break again is a good feeling. Butane will take forever to heat up to temperature, and frustration will set in before it happens. With oxygen added to just about any gas, the result will come much faster and without annealing the whole part in the process.
     
  13. ChrisCam

    ChrisCam Registered User
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    #13 ChrisCam, Jan 16, 2020
    Last edited: Jan 16, 2020
    Thanks S.B
    Before ordering I am running through the various permutations. Have you got propane or acetylene? I note in the UK Cookson Gold who sell the Smith torch sell flashback arrestors for propane but not mentioned for acetylene. I can source if needed acetylene or propane as have found a supplier. Acetylene is obviously hotter and the smallest tips will only work with this can you and Jerry and some arguments to go propane or acetylene.

    Also here's a great video link on using the torch:



    Chris
     
  14. shutterbug

    shutterbug Moderator
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    #14 shutterbug, Jan 16, 2020
    Last edited: Jan 16, 2020
    I use MAP. But anything will work better with oxygen.
    To use the smaller bottles available in hardware stores and the like, you will also need special regulators that fit those bottles. Check your welding supply store, or similar. Like this, but you can find them cheaper. You'll need two, and they are color coded.
     
  15. NEW65

    NEW65 Registered User

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    Interesting thread Chris - I’ve never soldered before but thinking of trying soon! How easy would it be to solder a broken brass threaded bar back in to place so that a lyre pendulum can be adjusted and reused again?
     
  16. Jerry Kieffer

    Jerry Kieffer Registered User
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    Chris
    Personally, to make a long story short, acetylene produces a higher temp in the smaller tips allowing one to accomplish repairs otherwise not possible with far greater ease.
    While I am not familiar with suppliers and availabilities in the UK, you are lucky to have many model engineers and societies that offer educational opportunities as well as demonstrations.

    I would suggest that you take advantage of these opportunities before purchasing equipment.

    Jerry Kieffer
     
  17. Jim DuBois

    Jim DuBois Registered User
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    Having silver soldered (brazed) dozens and dozens of brass pieces and parts it is neither difficult or risky. I use a Smiths torch on small parts, a Mapp gas torch for medium-sized parts, and a full-sized acetylene torch for the big stuff.
     
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  18. ChrisCam

    ChrisCam Registered User
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    Hi Jerry, thanks for the post
    In parrallel I actually do ask similar questions over this matter on a model engineering forum. Similar answers come back in that each person argues there case but no one todate has migrated from say Smith Little Torch propane to Acetylene or vice versa. As in many cases it is up to the reader to take a view. Acetylene while being hotter carries more risks in terms of over heating and dangerous gases but it is quicker to acheive desired melting points. My take is propane and oxygen is the way to go and if wrong I doubt I will never know as hopefully I will adjust to what I have and similarly would be the case of an acetylene user.

    Regards

    Chris
     
  19. NEW65

    NEW65 Registered User

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    I didn't notice your earlier post Shutt - looks like I had my question answered before I submitted it :D
     
  20. Jerry Kieffer

    Jerry Kieffer Registered User
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    Chris
    We all have opinions including myself, however they are of little value including my own until demonstrated. It is my personal experience that one must get out of the house and find demonstrations to get useful information.
    Having attended , Horological and model engineering events in the UK , it would seem these types of demonstrations are more readily available in the UK than any other part of the world. Again I would suggest taking advantage. Have you asked the supplier for their suggestion and demonstrations?

    Again personally, I wasted years gaining experience that demonstrations would have drastically cut short even though finding them was a pain in the butt. As they say, no pain no gain.

    Jerry Kieffer
     
  21. ChrisCam

    ChrisCam Registered User
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    Jerry,
    Whilst your suggestions at face value are a good idea I am not convinced I would be able to find such a demonstration of the Smith Little Torch that would demonstrate the benefits / disadvantages between using oxygen / propane as opposed to oxygen / acetylene in relation to a useful range of specifically horological repairs (to clock parts). I will indeed run the idea through my model engineers forum but would doubt it would yield any harvest: still you never know??
    Sometimes in order to be pragmatic you have little alternative but to take a view and get on with life.
    Chris
     
  22. Dick Feldman

    Dick Feldman Registered User

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    Butane open air torches have an ability to heat to 3578 degrees F.
    Propane open air torches have an ability to heat to 3623 degrees F.
    An open air propane torch should be able to be used to silver solder.
    The melting point of Brass is near 1984 F.
    925 sterling silver has a melting point of 1763 F.
    Soldering involves the joining of two dissimilar or similar metals and the heat applied must be below the melting temperature of both metals. More heat does not always assure a faster, stronger or better bond. The secret to soldering is to have the surfaces clean, clean and more clean.
    Normal silver solders used with jewelry have melting points and flow temperatures near :

    Melt F. / Flow F.
    Easy 1145 / 1205
    Soft 1240 / 1325
    Medium 1275 / 1360
    Hard 1365 / 1450

    The last sterling silver ring I built was soldered with hard silver solder and with a propane open air torch. The torch was purchased at a hardware store.
    The style torch is commonly sold to do plumbing, etc. soldering.
    I have a Smiths mini torch and seldom use it because it is oxy/acetylene. Acetylene is known to be a “dirty” gas and can easily contaminate a joint.
    Considering the cost, I believe a propane open flame plumbing torch will suffice for any soldering job for clock work.
    I also feel, like Willie, that silver solder may be over kill for clock work.
    There are many silver bearing soft solders that will exceed the demands of clock repairs.
    JMHO
    Dick
     
  23. shutterbug

    shutterbug Moderator
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    You have to get it pretty just right for the threads to work, but usually the break is above where the nut will end up after adjustment. Worst case, you can rethread the soldered area if needed.
     
  24. Willie X

    Willie X Registered User

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    If posible cut the upper part off about 1/4" so the repaired part will be above the area where the rating nut will need to travel. A butt joint, brazed to give you a slight 'build', will give you strength better than the unbroken part. It's just as easy to cut off the upper threaded part completely and replace the whole threaded part. Any time you can use a lap joint, or a 'let in' joint, by all means do so. When the joining's surface area is increased you can decrease or eliminate the brazing 'build' and usually be fine with soft solder. Willie X
     
  25. shutterbug

    shutterbug Moderator
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    Good point. Then you wouldn't even need to try to match the threads. You could use anything, and tap the nut to match.
     

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