Hairline crack in buttplate- Photos Added

[James]

My thought is that I have to start over, but maybe someone has a fix. I thought I had annealed the piece properly , but as I was trying to finish the fitting of the buttplate I notice small hairline cracks in the surface. Any ideas? Thanks, Jim

[Jim Kibler]

There is no way of assesing the problem without seeing it.  Perhaps you could include a photo or two.

[smylee grouch]

I have been told by others that when you get it finnished(but plate inleted) you can sweat solder with what ever solder you have and then dress it down. Suposedly you cant see the solder if its just a thin crack. I havent done this my self but I'm sure others on this fourm will chime in here who have tried this.  Good luck.    Smylee

[rich pierce]

steel or brass?  A buttplate is under no strain so it's not a structural concern but a cosmetic one unless it's ready to fall apart.

[James]

It is brass, here are some photos which I hope will show the cracks

[Jim Kibler]

James,

The crack looks pretty minor and I suspect it will be fine if left alone.  If you wanted, you could see if silver braze will take.  I've used this fix before with decent results.  Seems to work better than lower temperature solders.  The higher temperature flux seems to clean the metal better.  This is important in a crack that can't be cleaned.

[James]

I put a file to them and they do seem less of an issue than I initially thought. I still have to get the toe of the plate to meet the stock, so I suspect I should anneal again before going the last 3/32" to make contact. I had a butt-plate fitted long ago, but due to poor judgement early on while inletting the lockthat butt-plate had to be filed a lot to bring it into proportion and became too thin, so this is a case of trying to fit a new butt- plate to a butt stock which is ready for carving.

[bgf]

Get it all fitted up before you solder.  Do they go all the way through?  If you can grind a little trough on the backside, it might be easier to get flux and thus solder to flow into them -- they are so thin now, that you might have trouble, but if you can get flux in them, the solder will follow.

[kutter]

Fit it up to the wood.
Then repair the cracks with hi-temp silver solder and a proper flux.
It will run right into the tinyest of cracks if fluxed and heated just so it flows.
Don't over heat. That'll burn the flux,,then you'll have a tough time cleaning the surfaces down in the cracks before you can try soldering it again.

You'll be annealing the piece at the same time with amount of heat you'll be applying overall. Assuming you'll be repairing all in the same torch session.
The plate will be annealed and soft when done if you have to anymore last minute fitting or bending, but hopefully not!

[James]

 I annealed again using a bigger torch this time and what a difference. I got it right into place, but one of the cracks does appear to be a through crack.This is where I plead ignorance yet again. I see the recommendation to use high temperature silver solder and another for silver brazing. I have the heat sources, but which material do I need and what is the procedure? The welding supply place here tells me there is silver brazing and there is silver soldering, I have never done either so I don't know what to buy.  Thanks for the help to all of you, Jim

[kutter]

What I've always called 'silver soldering',, I quess is more correctly 'hard soldering' or 'silver brazing'

The filler metal, wether it be wire, ribbon or even a paste of flux and powdered metal,, is a mix of different alloys of copper, cadium, zinc(?) and different  amts of silver.
The % varys with the application but for a fix-it job like this most any will do. The different alloys will have different melt and flow temps.
A suitable flux for hard soldering is needed. Soft solder flux will not work.

Hard solders melt and flow in about the 900F and up range depending on the alloy of the solder.
An 875F flow hard solder would be considered a low temp hard (silver) solder IMHO.

A general purpose hard solder will leave a 'brass' colored joint fill. But it may not exactly match the base metal color.

They form extremely strong bonds.

A step up from that would be (brass) brazing. Filling the joint with a brass filler rod or wire to match the base metal. 
A flux is again needed. It's usually done on steel parts but can be used to repair brass & bronze parts.

Since the base metal and the filler are approx the same melt temp, careful work technique with a small tip torch is needed. A lower melt temp filler is a plus but not always possible.
Some that are really good with the technique can use scrap pieces of the base metal itself as filler. You can also end up with a melted mess that way!

Soft solders are commonly being refered to as silver solder lately. The ellimination of the lead in them for the health reasons and the turn to soft solders that are mostly all tin and a small amount of silver has led to them being refered to a 'silver solder'.

Confusing when you get someone like me refering to hard solder as silver solder too.