Silver Soldering Brass. How To Protect Threads?

schemer

schemer

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I have a "bonnet nut" that is cracked on an outside sillcock (outside water hose valve) that I want to fix. Problem is, I am pretty sure when I try to solder it the threads will suck some of the solder and make the job a failure or a lot of small dremel tool thread chasing. :eek: I identified the valve and went to the hardware and they had the same brand but when I tried to swap the bonnet nut, it is thicker but the external size looks the same. Apparently it has been updated over the years. The valve (I believe) is soldered into the plumbing and I would have to remove some bricks etc to replace it. I looked under the kitchen sink thinking I would have access under a thin plywood cover but I was wrong. Anyhow, does anybody know how to keep silver solder from flowing where you don't want it to flow (threads)? I am thinking I could take a broom handle or wooden dowel and try to thread it on to the bonnet nut while it is in clamped soldering position and maybe the wood would prevent the solder getting in the threads.
Anyone?
Thanks,
schemer
 
I'm trying to picture in my mind what you are trying to fix. If it's the big nut under the handle that holds the valve shaft down in the body of the house bib ??
Post up a picture so we know what you are dealing with.
****************Just Saying**************************Gator**********************
 
Just keep the flux off where you don't want the solder. Or if access to the other end of the copper, like under the sink or house, etc.....break that joint and just replace the whole bib, preferably with a frostproof.
 
Cobra said:
I have used steno correction fluid as a silver solder resist in silversmithing.
Apparently pencil lead will work as well. Use one of the very soft grades of lead.
Click to expand...
Do you mean any brand of correction fluid like white out? Thanks for the tip on pencil lead too.
schemer
 
grumpygator said:
I'm trying to picture in my mind what you are trying to fix. If it's the big nut under the handle that holds the valve shaft down in the body of the house bib ??
Post up a picture so we know what you are dealing with.
****************Just Saying**************************Gator**********************
Click to expand...

upload_2015-6-13_22-44-57.png
 
Tony Wells said:
Just keep the flux off where you don't want the solder. Or if access to the other end of the copper, like under the sink or house, etc.....break that joint and just replace the whole bib, preferably with a frostproof.
Click to expand...

It is cracked in two directions and will need to be fluxed properly to fix it. I may have to flux it and heat it in it's spread open position and then clamp it and reapply the flux and add the solder. I will get a pic of the real part tomorrow. I know how to change the whole piece but I looked and access is tough or I was looking at the joint and didn't realize it was the right one as it didn't seem to line up. It seems it was repaired before and bricks had to be removed and then put back in with new mortar.
Thanks,
schemer
 
SUCCESS! :applause 2: The Bic Brand White Out worked fine. I had an old half dried up bottle and painted the inside of the threads about .250-.375" from the center line of the crack. I soldered it with some Forney 6% Rosin core and it worked perfectly. I cleaned the threads with a dremel and brass wire wheel and it tightened right up and the leak is gone. Thanks for all the suggestions and especially the White Out. :)
 
Schemer,

Glad to hear you got it.
Thanks for posting back with the solution.

-brino
 
Glad to hear that it worked for you.
Yes, any brand of the correction fluid will work.
 
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