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Author Topic: Weak solder joint problem on brass.  (Read 7379 times)

tigertiger

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Weak solder joint problem on brass.
« on: April 01, 2009, 07:33:11 am »

On my Mary J Ward, the mast and booms use a gooseneck assembly as shown in the figure.

I have had 4 of these break at the join now. This is not faulty workmanship by a combination of design, and the fact that my boats get abused; or as I think, used in all weathers.

In the past I have replaced one of these goosenecks (main mast) with a kicking strap set up, but now I need to fix the one on the foremast. However I cannot use a kicking strap because of the deckhousing.

Is there any way I can make the joint stronger? or do I need to get used to the fact that I will have to keep repairing it?

Any advice appreciated.
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Umi_Ryuzuki

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Re: Weak solder joint problem on brass.
« Reply #1 on: April 01, 2009, 08:23:11 am »

What type of solder are you currently using?
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Rex Hunt

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Re: Weak solder joint problem on brass.
« Reply #2 on: April 01, 2009, 08:34:09 am »

can you get a web or fillet to support the join, increasing the contact area?

Right solder, right flux, right temperature......and above all cleanliness!

what about brazing it?

Rex
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boatmadman

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Re: Weak solder joint problem on brass.
« Reply #3 on: April 01, 2009, 08:36:41 am »

If you are not already doing so, I suggest silver solder is the way to go, and as previously mentioned, cleanliness is the key to good joints. Some form of etch prior to soldering should help as well.
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tigertiger

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Re: Weak solder joint problem on brass.
« Reply #4 on: April 01, 2009, 08:43:09 am »

Hi Guys
Thanks for the quick response.

I have not idea what solder was used before, as it was part as supplied.

I think I have silver solder and flux, but not any kind of etching stuff.
I am in China and finding stuff can be a bit of a pig.

Could I use brass rod as a fillet?
Maybe solder as before, then add a fillet as a step two, or would the first joint melt?
Do I need to do it in one go, if so, how would you suggest I hold it all together?

If using silver solder, do I need a hotter iron?
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boatmadman

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Re: Weak solder joint problem on brass.
« Reply #5 on: April 01, 2009, 08:48:12 am »

TT,

For silver solder you need the appropriate flux and a much hotter heat source - I use a blowtorch. Give the metal a good coat of flux, heat until cherry red, warm the solder (not melt) in the torch flame, and touch it to the metal, if the temperature is right the solder will wick into and around the joint and may leave a small fillet.

When its cool, you will think it looks messy, best thing now is to pickle it overnight in citric acid - it cleans off all the flux residue, then paint if needed.

Practise first on some scrap, its easier than it sounds.

Cant say often enough - cleanliness of components is the key to a good joint.

Ian
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tigertiger

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Re: Weak solder joint problem on brass.
« Reply #6 on: April 01, 2009, 08:50:50 am »

Thanks for that, I will give it a try.

Could I use spirit vinegar as a substitute for citric acid, before painting?
I don't think I would be able purchase citric acid easily here.
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boatmadman

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Re: Weak solder joint problem on brass.
« Reply #7 on: April 01, 2009, 08:52:24 am »

Can you get lemons? Squeeze a few, thats high in citric acid.

Ian
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tigertiger

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Re: Weak solder joint problem on brass.
« Reply #8 on: April 01, 2009, 08:53:24 am »

Lemon juice is easy.

Now all I need to do is find a blow torch  %%
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boatmadman

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Re: Weak solder joint problem on brass.
« Reply #9 on: April 01, 2009, 08:56:14 am »

Forgot to mention, I go over areas to be soldered with wire wool to clean up.

Let us know how you get on.

Ian
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John W E

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Re: Weak solder joint problem on brass.
« Reply #10 on: April 01, 2009, 08:59:06 am »

Hi tt try repairing it this way

aye
john e

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tigertiger

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Re: Weak solder joint problem on brass.
« Reply #11 on: April 01, 2009, 08:59:35 am »

Thanks for the help.

I will keep you informed. It will be a few weaks before I can get around to it.
And hopefully it will never fail, so I will not be able to report on that bit, hopefully  {:-{
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andrewh

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Re: Weak solder joint problem on brass.
« Reply #12 on: April 01, 2009, 09:01:06 am »

TT

Silver solder would be ideal for this joint - I expect it is about 1mm brass.
(Soft solder would be toooooo weak, even with a filler added each side to increase the joint area)
As with all soldering, cleanliness is the whole key to success,  (as well as the right flux  and enough heat.)

I plan how to hold the parts together for soldering (in this case a loop of copper wire twisted to hole them in the right place) then clean the parts obsessively with file, sandpaper and solvent.  dollop with flux, wire up on a firebrick (or brick or soldering mat) heat to dull red and the solder should flow like water.  allow solder to go solid then quench in water and clean up mechanically or in pickling acid (any acid or coca cola)

sorry if I am teaching you to suck eggs :}

My way of avoiding this break is to make the boom/jaws joint as well as possible, pin it with bamboo pins, then cut horizontally with a razor saw right into the jaws and boom as far as possible and glue in a piece of 1/64 ply to strengthen the whole shebang.  
I s'pose one could use pre-cured carbon sheet instead of ply for added rigidity.
Another thought that crosses the mind is to cut the jaws complete with a long tang in sheet brass (or printed circuit board), then build up the wood shape around this as a former.

andrew
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tigertiger

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Re: Weak solder joint problem on brass.
« Reply #13 on: April 01, 2009, 09:03:40 am »

Good idea Bluebird.

If I have to reconstruct, I will give that a go.

I may well do that if I get around to some of the bigger models, in my dreams. :embarrassed:
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Cheef

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Re: Weak solder joint problem on brass.
« Reply #14 on: April 01, 2009, 09:05:07 am »

I think there is a very good chance that the original joint would have been a soft solder joint as silver solder is very expensive so is usually avoided wherever possible by manufacturers.

Silver solder is a whole different ball game and, being considerably stronger, will do the job for you perfectly.
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andrewh

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Re: Weak solder joint problem on brass.
« Reply #15 on: April 01, 2009, 09:20:42 am »

TT,

All the thoughtful replies led me to a design which will work in soft solder - it has enough area for the solder to hold on (it would work with epoxy, too!)



andrew
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Proteus

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Re: Weak solder joint problem on brass.
« Reply #16 on: April 01, 2009, 10:45:38 am »

There is one problem with wanting to silver solder now . you cannot silver solder over a joint that has been soft soldered, no mater how well you clean it. so you will have to make new parts anyway or soft solder again

 Proteus
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roycv

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Re: Weak solder joint problem on brass.
« Reply #17 on: April 01, 2009, 11:05:36 am »

Hi TT. Lots of useful info there. Just for info,  if I remember rightly soft solder is 10 - 12 times stronger than epoxy.  Silver solder is almost a weld.  I have silver soldered small items over the gas hob flame but I usually wait til I am alone for this!

BUT, why are you using fake jaws?  I have 2 sailing boats with those sort of jaws on the sail booms.  They are held down by an unobtrusive hook and string to stop them rising up, and to stop the jaws leaving the mast there is a wire loop with kiddies jewelry beads as 'bearing surface' fitted into each side of the jaw, looks right and works. 
I have had one failure over about 5 years and a touch of glue fixed it.

Kiddies beads seem to be everywhere, I bet mine came from China! Now there's a thought!

regards Roy
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tigertiger

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Re: Weak solder joint problem on brass.
« Reply #18 on: April 01, 2009, 12:28:49 pm »

Hi Roy

I have done what you suggested on my main mast, but the formast is about 1/2" (12mm) approx in front of a deck house. So a pull down line is not possible. I could attache the very front of the boom, but the back end would rise significantly.
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Circlip

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Re: Weak solder joint problem on brass.
« Reply #19 on: April 01, 2009, 04:15:40 pm »

As Proteus has already said Tiger, you will have to start from scratch to Silver Solder. A cheap flux for Silver Solder is Borax made into a thin paste with water and a drop of washing up liquid added. Problems with Citric acid? Before we became "Green" incensed, a diluted quantity of Battery acid was the preferred pickling solution, and add the acid TO THE water, tother way round is spectacular and VERY dangeroux.

  Regards  Ian.
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Umi_Ryuzuki

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Re: Weak solder joint problem on brass.
« Reply #20 on: April 01, 2009, 05:32:26 pm »

Look for a solder that is at least 56% silver.

The 60/40 tin /lead stuff is probably what you are currently using.
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