Need silver solder advice

A

AMMASHOOTA

Gary Gruber
I have done a ton of soldering in my day, but not silver solder. I can't imagine it being any different from other solder, but I did run into a problem this weekend.

I am putting open sights on a barrel and started with the rear sight. Prep was normal and I tinned it with Brownells Hi-force 44 (650 degrees). The sight ramp is fairly thick so I tried Mapp gas. Could not get ramp or barrel hot enough to melt the solder.

I then tried Mapp with Oxygen. Got it hot enough but burned off the flux. After a couple of failed attempts I switched to Brownells 70 PA solder (425 degrees). No problem getting the solder to flow with Mapp gas alone -- rear sight is now affixed solidly.

Is there some trick to getting the Hi-Force to bond properly? Is this much tensile strength required for a sight that will be also be screwed to the barrel?
 
I recall my smith mentioning that a specific type of abrasive prep must be used in order for high temp solder (silver braze) to stick. Don't recall if it was aluminum oxide or silicon carbide that was required.
 
Silver requires about 1200 F. Many gunsmiths use a product called Force 44 that is about 80% as strong as silver and melts about like lead/tin solder.
 
I am assuming these two products are silver because when I entered that in the Brownells search window, it displayed these items, among others. Obviously, if silver requires 100-1200 to melt, these must not be them.
 
There are solder and brazing compounds that both contain silver. The temp range is determined by what the silver is alloyed with. Just because a material contains silver does not automatically make it a high temperature brazing material. Silver solders use ~400-500°F and silver braze ~1200°F.

An example of a (4%) silver solder alloy http://www.harrisproductsgroup.com/en/Products/Alloys/Soldering/Lead-Free-Solders/stay-brite.aspx

Low percentage (6%) silver braze alloy: http://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/Phos-Copper/Stay-Silv-6.aspx

High percentage (56%) silver braze alloy: http://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/High-Silver/Safety-Silv-56.aspx
 
Last edited:
WSnyder said:
There are solder and brazing compounds that both contain silver. The temp range is determined by what the silver is alloyed with. Just because a material contains silver does not automatically make it a high temperature brazing material. Silver solders use ~400-500°F and silver braze ~1200°F.

An example of a (4%) silver solder alloy http://www.harrisproductsgroup.com/en/Products/Alloys/Soldering/Lead-Free-Solders/stay-brite.aspx

Low percentage (6%) silver braze alloy: http://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/Phos-Copper/Stay-Silv-6.aspx

High percentage (56%) silver braze alloy: http://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/High-Silver/Safety-Silv-56.aspx
Click to expand...

Thanks for the info. I guess I just can't figure out why I had so much difficulty with the higher temp one. I was using the recommended flux, but just could not get the heat right. The sight is on there, I don't believe it is going anywhere...

I used to be able to braze copper plumbing pipe with my temper alone...now I have to rub two politicans together rapidly to generate enough heat for a good joint...
 
How quickly were you able to get up to temp with the mapp/oxy? Heating time can be a factor along with ultimate temp. You can kill the flux if you have to heat for too long trying to get to temp. It is usually helpful to get the material up to brazing temp quickly without without lingering and overheating to get a good joint.
 
Brownells 44 comes in regular and hi temp (450 & 650) with different flux for both, sounds like you have the high temp which I have not used, however regular 44 is plenty strong and preferred by most smiths plus mapp is adequate to get it to temp. The acid flux is fine for tinning but use rosin when you join them to avoid trapping acid and causing problems down the road. Maybe you have hi temp and regular flux? The above suggestion about heating to long is possible also and I would add that having the part in and out of the flame a lot will allow it to oxidize.
 
WSnyder said:
How quickly were you able to get up to temp with the mapp/oxy? Heating time can be a factor along with ultimate temp. You can kill the flux if you have to heat for too long trying to get to temp. It is usually helpful to get the material up to brazing temp quickly without without lingering and overheating to get a good joint.
Click to expand...

I think you hit the nail on the head here. I believe I took too much time getting the joint up to temp. When I pushed the heat to the barrel instead of the sight base, I got the solder to melt and join quickly.
 
IHO, properly done soft solder is more than strong enough, particularly when a back-up screw is involved. And, there is much less chance of bore damage.
F1.
 
There is a reason that one has to be certified to silver braze aircraft or submarine parts.

Cadmium is your friend when it comes to silver brazing.

Epoxy would have been your best bet.
 
Dans40X said:
There is a reason that one has to be certified to silver braze aircraft or submarine parts.

Cadmium is your friend when it comes to silver brazing.

Epoxy would have been your best bet.
Click to expand...
Winner, winner!
 
Dans40X said:
There is a reason that one has to be certified to silver braze aircraft or submarine parts.

Cadmium is your friend when it comes to silver brazing.

Epoxy would have been your best bet.
Click to expand...

Funny you should mention that. After several failures with the higher temp solder, I resolved if the next attempt should fail, I would use epoxy.

The problem with epoxy is that I do not believe it could withstand the heat of the hot bluing process. I am glad my last attempt worked...
 
AMMASHOOTA said:
Funny you should mention that. After several failures with the higher temp solder, I resolved if the next attempt should fail, I would use epoxy.

The problem with epoxy is that I do not believe it could withstand the heat of the hot bluing process. I am glad my last attempt worked...
Click to expand...

Look for brazing alloys that contain phosphorous (around 5%).
These can be the self fluxing.

For steel work there are special high temp fluxes, but use them with plenty of ventilation.
They release some nasty toxic stuff.
 
Tig Welding them is the way to go..

For the last couple of years I have communicated with Dan Armstrong regularly, and he has actually been able to teach me a thing or two, for which I am extremely grateful. Dan has forgotten more than most about Bolts, Bolt Timing, and Bolt Welding. I have had him weld several bolts for me personally. About 3 years ago I bought a Miller Dynasty 200 Tig Welder. It is a newer Inverter style welder. Dan has coached me through Pulse/Purge, Fusion welding. I have duplicated much of the set-up in a similar fashion as Dan has for Tig welding Bolts.

In years past I O/E silver soldered bolt handles back on when re-timing bolts. In my opinion the quality of Remington bolt handles, and bolt bodies are hardly worth fixing/reusing, I recommend truing up the actions (including reaming bolt races) and replacing the OEM bolts with over sized after market bolt bodies and bolt handles. This removes slop, and corrects timing issues.

Nat Lambeth
 
When soldering always apply the torch to the heaviest part first. Brownells force 44 is just 5% silver, and is great for sight ramps. Bluing must be abraded off where the solder is to go. Tinning the parts first will help flow in the solder. TIG welding on a barrel will oxidize/scale the bore.
 
Last edited by a moderator:
xs hedspace said:
When soldering always apply the torch to the heaviest part first. Brownells force 44 is just 5% silver, and is great for sight ramps. Bluing must be abraded off where the solder is to go. Tinning the parts first will help flow in the solder. TIG welding on a barrel will oxidize/scale the bore.
Click to expand...

Thanks for the advice. I finally got the front and rear sights, and barrel band installed this weekend. Two tries on the rear sight ramp, front and band went on easily.

Biggest problem on the rear ramp is devising a viable spring clamp to hold the ramp while heating it. While one is available from Brownell's, I didn't want to purchase it for a single use.

Am finishing the bluing now, sights are installed and it looks really nice...
 
You must log in or register to reply here.
Back
Top