Soldering, tinning and sweating question

Rebelson

Rebelson

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For context I had an late night yesterday in the shop tinkering away. An old 12 gauge Kessler bolt gun was picked as the next project gun in line to practice on (rust bluing, refinishing the stock, cut it for chokes etc.) I want to put a scope base on it and make it a budget deer and turkey gun project for fun and experience.
I have blank rail stock and bases that could be machined and fitted. But it needs to be a barrel mounted rail or base set for an LER scope due to receiver design constrictions, so I'll have to tin the barrel and the base and sweat them together. Doesn't sound that bad, except all my rail stock and bases are aluminium...

I'd just buy steel rail, but now I'm determined to find a way to bond the dissimilar metals by using specialty solder and test it's durability. wether it goes good or bad I still gain experience and maybe even a new ability. I did some research into muggy weld super alloy #1, it has a great track record boasting that it has 20 000psi bond strength and can solder aluminium to stainless, brass, mild steel, high carbon steel etc. it's melting point is 350°f so within 10°f of 60/40 tin solders melting temp. So it should be able to take the max barrel temp of a bolt action 12 gauge

Has anyone here tested it or worked with it to sweat on a aluminium base to a barrel? Or even just messed around with it or other products bonding steel and aluminium in any capacity? Is there any other products or methods that I'm unaware of for this soldering experiment? Thanks in advance for your insight
 
Rebelson said:
For context I had an late night yesterday in the shop tinkering away. An old 12 gauge Kessler bolt gun was picked as the next project gun in line to practice on (rust bluing, refinishing the stock, cut it for chokes etc.) I want to put a scope base on it and make it a budget deer and turkey gun project for fun and experience.
I have blank rail stock and bases that could be machined and fitted. But it needs to be a barrel mounted rail or base set for an LER scope due to receiver design constrictions, so I'll have to tin the barrel and the base and sweat them together. Doesn't sound that bad, except all my rail stock and bases are aluminium...

I'd just buy steel rail, but now I'm determined to find a way to bond the dissimilar metals by using specialty solder and test it's durability. wether it goes good or bad I still gain experience and maybe even a new ability. I did some research into muggy weld super alloy #1, it has a great track record boasting that it has 20 000psi bond strength and can solder aluminium to stainless, brass, mild steel, high carbon steel etc. it's melting point is 350°f so within 10°f of 60/40 tin solders melting temp. So it should be able to take the max barrel temp of a bolt action 12 gauge

Has anyone here tested it or worked with it to sweat on a aluminium base to a barrel? Or even just messed around with it or other products bonding steel and aluminium in any capacity? Is there any other products or methods that I'm unaware of for this soldering experiment? Thanks in advance for your insight
Click to expand...
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Cheers
 
One issue i see is the expansion rate of the dissimilar metals.
Granted a bolt shotgun shouldn’t experience significant heating.
Have you looked into some of the new chemical bonding agents out there?
 
Try it with some scrap aluminum and steel first would be my only suggestion, I’ve only ever soldered similar metals. Steel and stainless steel, have brazed a fair bit of brass to steel and the melting point was tricky with brass. I don’t know if aluminum would be the same.

With brass stock and brass rod when you got it to the point the brazing rod would melt and flow you were very close to the point the brass stock would do the same, would be easy to wreck things if you weren’t paying attention to colour changes in the thicker piece being brazed.
 
scott.y. said:
One issue i see is the expansion rate of the dissimilar metals.
Granted a bolt shotgun shouldn’t experience significant heating.
Have you looked into some of the new chemical bonding agents out there?
Click to expand...
I messed around with jb weld and a couple other generic hardware store epoxies in the past on ramp sights, not one made it to 50 rounds without delamination. Surface prep was done meticulously. Needless to say me and steel epoxies never shook hands. I'd rather just experiment and pick up a new skill along the way
 
Rebelson said:
I messed around with jb weld and a couple other generic hardware store epoxies in the past on ramp sights, not one made it to 50 rounds without delamination. Surface prep was done meticulously. Needless to say me and steel epoxies never shook hands. I'd rather just experiment and pick up a new skill along the way
Click to expand...
I hear you.
There are more exotic chemical bonding agents out there.
We used a Kennemetal product to put a propeller on a shaft years ago.
3000 hp. It worked just fine. Reports indicated that it ran for several thousand hrs.
Cannot for the life of me remember the product name.
Good luck with your project.
 
What you need is Belzona. The problem is it isn’t sold to the general public and you will need someone in industry to score you some. You don’t need a whole lot. If you can make a contact a lot of time they have left overs from bigger jobs. Think Devcon X 100 and you’re getting close. We use it on most anything, bearing fits, pump housings, the neighbors snowblower driveshaft, dirt bike engine cases, lol…you get the picture.
 
I just tried soldering aluminum with low temp silver solder last week.
It seemed to need to be worked in fairly thoroughly at minimum temps to get it to wet out. A dedicated wire brush or acid brush might be the ticket.
Once it was wetted it behaved properly. I could see it working very well for your intended purpose.

Please note that all this is based on one experience! I had never had the need to solder aluminum in the past.
 
Jonnyofalltrades said:
I just tried soldering aluminum with low temp silver solder last week.
It seemed to need to be worked in fairly thoroughly at minimum temps to get it to wet out. A dedicated wire brush or acid brush might be the ticket.
Once it was wetted it behaved properly. I could see it working very well for your intended purpose.

Please note that all this is based on one experience! I had never had the need to solder aluminum in the past.
Click to expand...

I'm game to test the idea on scrap. For context so I can give it a shot, was it aluminum to aluminum or aluminum to carbon steel? Also when you say low temp silver solder, are you talking about your run of the mill hardware store electrical solder? Or a different alloy? And what type of flux? Thanks for the idea!
 
I believe you will not be successful in bonding aluminum to your steel barrel by any soldering means... possibly with an epoxy though... until it falls off on repeated firings with the barrel expanding/contracting with the pressure.

It is way simpler and almost a guarantee it will work if you simply obtain a steel base and get on with it.
 
Rebelson said:
I'm game to test the idea on scrap. For context so I can give it a shot, was it aluminum to aluminum or aluminum to carbon steel? Also when you say low temp silver solder, are you talking about your run of the mill hardware store electrical solder? Or a different alloy? And what type of flux? Thanks for the idea!
Click to expand...
I was using Oatey Safe-flo solder and flux.
It's supposed to give around 20'000psi tensile strength bond. I have no idea what I was getting for bond strength on the aluminum, as I was simply patching holes in a 9" X 13" baking pan. Hafta keep the wife happy!
Now you have me curious. I might take a few minutes to do some testing this weekend.
 
guntech said:
I believe you will not be successful in bonding aluminum to your steel barrel by any soldering means... possibly with an epoxy though... until it falls off on repeated firings with the barrel expanding/contracting with the pressure.

It is way simpler and almost a guarantee it will work if you simply obtain a steel base and get on with it.
Click to expand...
Your right about the steel bases, that's Definitely the plan now.
 
While I was in school, we dealt with adhesives that were stronger than the metals being bonded. Not inexpensive. And, they required a Hot Bond machine, a controlled source of heat plus time controls....
But, the tensile test showed that it was a stronger joint than the base material!

The only other folks that I am aware of, that have stuck Aluminum to Steel and made it happen, were some folks in the US Navy that used a LOT of explosives to make it work.

Gonna say, on average, if it claims to stick iron to aluminum, it's probably a rip-off and a scam.
 
Ok, so I did some experimenting over the weekend. Very scientific.
I found that a flux that I normally used for electrical soldering did the best job of getting the solder to wet out on aluminum. The only really good way I found was to scrub the melted solder around on the aluminum with a folded up scrap of 220 sandpaper that had some flux on it. Otherwise the solder just beaded and rolled off. I was using Oatey Safe-flo silver-bearing solder and flux, but the Safe-flo flux didn't work as good as an ancient can of Kester soldering flux that I inherited from my Grandpa. No idea of a modern equivalent, but I think it's pretty generic electriconics soldering flux.
I was able to get a pretty respectable bond on one occasion. A 3/4" square pad was the joint between steel and aluminum. Then a fish scale was used to pull 4" away from the joint until it failed.
It took 10 lbs pull to separate the joint when using the Oatey Safe-flo flux. A JB weld test bond also failed in that ballpark, maybe slightly higher.
Switching to Kester flux I was able to get 35 lbs pull before failure. Switching to a steel on steel joint DOUBLED the pull required to break the joint. Also damaged my fish scale. Oops
Of course, I forgot to take many photos.
I intend to repeat the tests, because I really expected better results from the JB Weld, and I would like to try 50/50 solder.
All joints were prepped on a belt sander with some random belt that happened to be on there. Maybe 80 grit?
I look at it this way. I can easily bond aluminum wires to other metals when soldering electronics, why not a solid chunk of aluminum?
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Aluminum forms an oxide layer that cannot be soldered to almost instantly when freshly machined/sanded aluminum is exposed, this is why your sandpaper trick was able to get it to wet out. You don't really want that oxide in the weld so figuring out some way to do this in an oxygen free environment is your best bet. It's the same reason tig welding requires argon.
 
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