Silver soldering underlugs?

[Tennessee.45]

I have a an idea on how to do it but could use some guidance on silver soldering underlugs to the barrel.

[jerrywh]

 Do not use High temp silver solder on under lugs of a barrel.  Low temp is OK.  The heat required to melt high temp solder will warp the barrel even if you heat it evenly all the way around it will choke it.  Low temp will not effect the barrel if the temp is held below 800° F.

[D. Taylor Sapergia]

Silver soldering involves two processes:  the first refers to hard brazing with silver bearing wire involving red heat.  The second involves using silver bearing low temperature solder.
The first is not appropriate for attaching lugs or anything else to a barrel. 
The second is soft soldering with silver bearing solder at much lower temperature and can be used for attaching sights, lugs and ribs to barrels.
Steel must be clean:  rough polish with ~ 180 grit abrasive cloth, and then never touch that area again with fingers until soldering is complete.  After cleaning with abrasive, the area should be fluxed and tinned, as should the piece to be joined.  Once that is accomplished, the two parts can be clamped together, heated to make the solder flow, remove the heat, cool and clean up.

[D. Taylor Sapergia]

Jerry beat me to it, and as usual, his answer is tack on and succinct.

[JCKelly]

Heating a barrel always includes possible warpage.

In theory if you heat the thing uniformly it will be fine.

In practice it is nearly impossible to heat that dovetail the same temperature as the top of the barrel in that area.

In short EngineerSpeak, 200F equals the yield point.

Huh?

If one side of the barrel is heated 200F hotter than the other, it will take a permanent bend. 

I used to be involved with high temperature stuff, and there is almost not such thing as uniform heating. There are, however, a lot of distorted high temperature fixtures. Experience has shown this for about a century now, but it will never change. It is nearly impossible to convince a college educated engineer that this is so. A skilled tool maker knows better.

One of the 20th Century gods of Mechanical Engineering, Stephan Timoshenko, developed a formula for it. Boils down to a 200F (or less) thermal differential will permanently distort a piece of metal.

Google it.

[Bill Raby]

It is nearly impossible to convince a college educated engineer that this is so. A skilled tool maker knows better.

   I got to deal mostly with metallurgists and materials science guys. Hardly any of them had any hands on work experience. Always seemed like the fancier the degree, the less they knew.

[smylee grouch]

What kind of barrel are you working with Tennessee, rifle-straight,tapered, swamped or fowler/trade gun?

[ron w]

It is nearly impossible to convince a college educated engineer that this is so. A skilled tool maker knows better.

   I got to deal mostly with metallurgists and materials science guys. Hardly any of them had any hands on work experience. Always seemed like the fancier the degree, the less they knew.

 
    not "the less they knew",....rather,...the more they have convinced themselves they're right !.

[gumboman]

This could explain why my fowling piece shoots 20 inches low. All 4 lugs on the 44 inch barrel were soldered on.

[Lucky R A]

    You do not need silver solder, plain plumber's solder will do fine.  I have soldered hundreds of underlugs on and have no problems with barrel distortion.  Clean the area where you will put your four lugs, tin the area with a lite layer of solder, tin the bottom of your lug.  Give the lug a light swipe of flux, hold it in the correct location and heat both the lug and the barrel until the solder melts and fuses together.  Hold it in the correct position until the solder sets, the solder will go from a bright shine to a dull shine when it has set.  I make most of my underlugs from folded metal, they are wider than the barrel flat.  I immediately use a cold chisel to trim off the excess.  The plumbers solder holds them securely throughout the trimming process--if it doesn't your solder joint wasn't good to start with.  this is a safe and secure way to install underlugs that requires no cutting of the barrel metal---The nice thing is if you screw up it is easily fixed...Ron

[Tennessee.45]

What kind of barrel are you working with Tennessee, rifle-straight,tapered, swamped or fowler/trade gun?

I'm using a c weight swamped .58 from colerain, Scott said that .030 would be the max he would go on the dovetails in the waist, I'm at .030 and the dovetails won't fit, so I'm just gonna solder them on, I'm using low temp plumbing silver solder 430 degree melting point I believe.

[Eric Krewson]

Use solder paste in a syringe, quick easy and you won't be able to knock them off with a hammer.

The picture is of some paste with copper in it that I found at Lowe's, they no longer carry it. It worked just fine for soldering underlugs and didn't have a copper color once used.



I have since bought a tube the same stuff that is silver bearing solder off eBay.

[D. Taylor Sapergia]

I use a solder I bought at an electronics store...contains 2% silver, and is very fine wire, ~ 1/16" diameter.  It melts long before the metal changes colour, in fact, if the steel changes colour, the solder job is ruined.  Solder will not bond with steel through any oxide.

[Tennessee.45]

After several failed attempts, I think I've got the solder to stick, will check tonight after work, but if not I'll try the solder paste from TOW since I'm needing a few parts anyway

[Dphariss]

Back many moons ago I built my commercial pilots license required time (most of it) in an aircraft completely bonded with epoxy. AA-1A American Trainer. Don't know that it had more than a handful of rivets holding the fiberglass wing tips on and maybe a few in some other places.  Maybe I will glue underlugs on. No real stress to the steel.


Dan

[bgf]

Back many moons ago I built my commercial pilots license required time (most of it) in an aircraft completely bonded with epoxy. AA-1A American Trainer. Don't know that it had more than a handful of rivets holding the fiberglass wing tips on and maybe a few in some other places.  Maybe I will glue underlugs on. No real stress to the steel.


Dan

Dan,
I actually did this on my chunk gun barrel last year in a rush to get finished for york.  It was a large lug and I used 5 minute epoxy.  I broke it a couple of weeks ago (after a year of matches) when I was having trouble getting up and put a good bit of my 250# on the barrel.  I would guess it would still be holding if I wasn't a klutz.  Not recommending it, but it worked.  I had intended to solder  it last year, but sorta forgot about it.  Imagine that better epoxy would hold even better.  I just use s dab of the five minute stuff to  lock sights down typically.

[Dphariss]

    You do not need silver solder, plain plumber's solder will do fine.  I have soldered hundreds of underlugs on and have no problems with barrel distortion.  Clean the area where you will put your four lugs, tin the area with a lite layer of solder, tin the bottom of your lug.  Give the lug a light swipe of flux, hold it in the correct location and heat both the lug and the barrel until the solder melts and fuses together.  Hold it in the correct position until the solder sets, the solder will go from a bright shine to a dull shine when it has set.  I make most of my underlugs from folded metal, they are wider than the barrel flat.  I immediately use a cold chisel to trim off the excess.  The plumbers solder holds them securely throughout the trimming process--if it doesn't your solder joint wasn't good to start with.  this is a safe and secure way to install underlugs that requires no cutting of the barrel metal---The nice thing is if you screw up it is easily fixed...Ron

This then begs the question. Have you looked for distortion? And would you have the equipment to find it if it were slight as it probably is.

Dan

[Dphariss]

Back many moons ago I built my commercial pilots license required time (most of it) in an aircraft completely bonded with epoxy. AA-1A American Trainer. Don't know that it had more than a handful of rivets holding the fiberglass wing tips on and maybe a few in some other places.  Maybe I will glue underlugs on. No real stress to the steel.


Dan

Dan,
I actually did this on my chunk gun barrel last year in a rush to get finished for york.  It was a large lug and I used 5 minute epoxy.  I broke it a couple of weeks ago (after a year of matches) when I was having trouble getting up and put a good bit of my 250# on the barrel.  I would guess it would still be holding if I wasn't a klutz.  Not recommending it, but it worked.  I had intended to solder  it last year, but sorta forgot about it.  Imagine that better epoxy would hold even better.  I just use s dab of the five minute stuff to  lock sights down typically.

It was just something I thought of, partly in jest. But it is an option. However, most of the generic epoxy on the market that is not up to the job.

Dan

[Dphariss]

I used to work for a company that silver brazed front sight lugs on the military models using an induction machine and I suspect there was distortion. But I never knew to look. Had I found it nothing would have changed.
Even  shallow dovetails in a B weight 50 cal will show bore distortion after proof loads are fired but it requires a tight oiled patch on a jag with a short bearing surface.
I could tell some things about button rifling barrels then final machining them without normalizing them between the buttoning and the machine work. A half octagonal barrel is always prone to bore distortion at the wedding bands/oct to round transition and if made as described above the change in bore size is shocking.  While the ML barrel is virtually always cut rifled this does not exempt it from bore anomalies if the steel has high levels of internal stress and then has significant material removed from the exterior to form a swamp or other visual features. But the modern forms of bore inspection are not used on ML barrels. The ML shooter, for the most part, is far less discriminating in accuracy than competitive shooters in the "real" (if you will) world.

Dan