Soldering front sight

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Last Post 11 February 2014

CBA Member

tturner53 posted this 04 April 2012

I'm contemplating trying to attach a new front sight on a rifle barrel. According to the gunsmithing books I have there's a process called 'tinning'. This is different from sweating copper fittings on which you clean, flux, and heat the fitting, then apply solder to the thing. Will sweating work on a sight? Will it draw the solder into the joint like copper does? Or do I need to learn this 'tinning' method? Thanks for any advice.

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Standard Member

onondaga posted this 04 April 2012

Tinning is not required and limits accuracy of jigging. Parts should be clean, fluxed and jigged then heated enough that the parts will melt the solder into the joint. Never allow the neutral area of the flame to leave the joint area or immediate oxidation will occur and prevent flow. Done correctly, the whole heat/flow cycle is very fast. You can pull the solder toward the heat only if you have not overheated, If you have overheated, then the solder will just run out of the joint. Soldering is a delicate balance of heat.

If you have access to resistance brazing equipment, it is much easier to control than a torch. I have decades of experience resistance brazing with silver and gold alloys to fix cobalt chrome and stainless steel parts together in the Dental Laboratory.

A very good option for fixing sights is to micro-spot weld and then silver solder. The spot weld will not allow the parts to move when silver soldering.

Gary

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CBA Member

tturner53 posted this 05 April 2012

Thanks Gary. All I have as far as a torch is a regular plumber's type. I will give it a try without tinning. Out of curiosity, I've read about people using epoxy for this job and claim it stays put. Anyone with experience there? Just weighing my options.

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CBA Member

Ken Campbell Iowa posted this 05 April 2012

hi mr. t....i have successfully mounted several scopes with epoxy .... mostly for a temporary setup or where i didn't want to put holes in an old rifle.

point is that a scope is much more massive than a front sight. unless the gun is for self-defense...or grizzly bears ....it might be worth a try with the epoxy.

most of the strength of epoxy attachment comes from “encapsulation ” so it helps to create grooves or holes that the epoxy can grab. if a temporary job, such as a few shots to check blade height etc, roughing is probably not required. for permanent, i like to drill a lot of small holes...1/16 inch is ok.... in the surfaces.

use good epoxy .... 2 part type NOT 5 minute types. jb weld, marine-tex are some of the best...devcon filled is great but is visible with the filling. sig model airplane epoxy is good, almost clear, can get it at hobby shops.

most epoxies set up in 1/2 to 1 hour, at room temps. but dont shoot the gun for 3 days for curing...full strength .

re: silver solders...consider brownells' medium heat silver solder...this will melt ok with a benz-o-matic....i put a front site on a win94 with it, worked just fine.

oh, since the epoxy is about $30 for a glob, you can store leftover in a refrigerator for years. you could use the extra for a pillar bed job (g).

hope this helps.

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Standard Member

onondaga posted this 05 April 2012

If all you have is a plumbers torch, go to a welders supply shop and get the lowest fusing, low silver alloy solder they have and the recommended flux. If your torch will work with Mapp gas , use that too. Silver solder fluxes are usually a white paste and turn glassy from heat before hot enough for solder to flow.

I have only used epoxy once and put sights with large bases from a .22 onto a single shot 20 Ga. I remember it was 4 hour setting time A+B type clear epoxy and it has held over 20 years now and my grandson uses the gun regularly. The bases were large and well matched to barrel diameter. . I sand blasted surfaces for preparation.

Gary

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CBA Member

AWOL posted this 14 April 2012

Gary, Would you explain please about the neutral part of the flame? I often have trouble with silver soldering & think I somehow allow the parts to get sooted over. Perhaps it is this oxidation you mention. Thanks.

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Standard Member

onondaga posted this 14 April 2012

AWOL, Sure.

If you are getting soot on your work silver soldering you have let the neutral zone of the flame go out of contact with the work and allowed the carbonizing area or air to be exposed to the work.

A Mapp gas or propane torch flame has 3 principle zones. Closest to the torch head is a bright single or multiple bright primary cones of flame. The very tip end of the primary cone is the hottest area of the torch flame. Surrounding the primary flame is a neutral cone of blue flame. Depending on your torch adjustment there may be a third paler or even yellowish outer cone of carbonizing flame.

If the outer carbonizing flame or the the room atmosphere comes in contact with the work during the soldering or brazing, then oxidation of the work surface and the solder or brazing material will occur. If the outermost 3rd cone of flame touches the work you will get soot on the work.

Begin heating the work area with the primary tip of flame, keep it moving but do not allow the 2nd or 3rd flame cones to leave the joint area. You can back off the primary cone for less heat but again keep the 2nd cone enveloping the joint area or you will get oxidation or sooting . The common error is that the flame is waved around the joint area in an attempt to evenly heat a joint area that is too big for the torch flame and then the oxidizing or sooting starts.

You really have to just go in and do it right the first time and get out, not wave the torch around or let the neutral flame leave the work or you will have problems.

The best way to learn this is to watch someone that is really good at it and ask questions. Catch a jeweler or Dental Technician torch soldering with gold or silver at a craft show or in his shop or lab and he will tell you about the flame zones he uses if you ask.

Gary

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Standard Member

CB posted this 15 April 2012

Gary,

Thanks for the terrific short course on soldering. I wish I had had it 50 years ago before I screwed up so many attempts.

Ken,

Thanks for the list of the best epoxies. I have usually had good luck when I could get both surfaces really clean. I have tried to use some over the years that were much worse than others but can't remember from one time to the next. I will paste your list and Gary's torch tutorial up over my workbench.

John

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CBA Member

tturner53 posted this 15 April 2012

Thankyou all for so much good info. I definitely am learning here. Haven't made a decision yet on this project, but am considering taking the coward's way out and just replacing the front sight blade with one made by modern Mauser.. The base is a milsurp job that's been holding for 50+ years on a 7.62 Nato Chilean rifle barrel. It's a tad longer than what I want for a doomsday special, still thinking over my options. The theme is a Ruger 'Scout Rifle' on a 98 parts gun chasis. At a glance the M1 Carbine front sight looks like a possibility, I'd like something with ears, Looks cool. I'm using an old but never installed 98K stock of ancient birch, I think. May tiger stripe it like some nice old muzzleloaders I've seen. My action, barrel, and stock were all made in different countries and different decades but is a drop in fit! Wood to metal aint bad at all.

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Standard Member

Sonny Edmonds posted this 15 April 2012

Something a bit more “modern” you fellows might consider is Cyanoacrylate glue. (AKA: Super Glue, and other names) Your wife might have some for broken fingernails. But it is widely available, even at the big box stores.

It is pretty amazing stuff, and comes in different viscosity's. From water thin, to gap filling thick, and even rubbery finished consistencies (flexible).

A drop on a front sites dovetail will render it glued in place in seconds.

I have used it in a myriad of applications. And helped pioneer it as a finish for wood turnings in the 1990's.

Quite a bit easier to use than soldering... ;)

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CBA Member

AWOL posted this 15 April 2012

Thanks Gary, you've helped a lot. So one thing I do wrong is move the torch around while I heat up the parts.

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CBA Member

tturner53 posted this 15 May 2012

I got a replacement front sight blade from Brownell's. A little filing on the blade base and it fit pretty good, nice and snug. It's taller than the original inverted V blade and is the 'Patridge' type. So now the notch in the rear sight has to be opened up a bit to accomodate the square wider front blade. Anybody know the typical relationship between the width of the notch and the width of the blade? I'm guessing it should be about the same. The blade width is .078. I have a 1911 slide rail file that is .081 on one side. Also, I decided to keep it looking 'issue' and bought a 1912 Chilean Steyr stock set from Sportsmans Guide, about $30 includes stock hardware. It's not too bad and should clean up nice. So now I'm back to a 1912 rifle in 7.62 but with an old GEW action. Would'a been cheaper to just buy the Chilean 7.62 complete in the first place, but it's mine now. I may d&t for a receiver sight, maybe even a scope base. Then it will be really versatile, several configurations possible. I need a receiver sight that won't interfere with clip loading to preserve the 'scout rifle' idea.

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Standard Member

Reg posted this 16 May 2012

I used to attach front sights using silver solder as it is not affected by the hot blue tanks, soft solder is dissolved in them. Now I just polish and blue and attach the front sight using Brownell's Accra Glass. make sure all surfaces are perfectly clean to get the best bond. I hand polish everything and having that sight off sure makes barrel polishing easier. This system works with all sporting use rifles even in temps down as low as 20 below. I do not think it would stand up with a high cyclic rate weapon as temps of 350 degrees f. will break the bond. Most barrels never get this hot but over a sustained use there might be some effect. Have had to go back and re-blue at least two over the course of time and knowing they were glassed on I didn't leave the barrel in the tank any longer than needed to get a good dark blue then pulled them quickly out and dunked in the cold water tank. Generally the tanks are running about 295 f. so temp should not have any effect on the bond but do worry about any chemical reaction so the reason for the quick blue then the cold dunk. So far, all have held.

:fire

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CBA Member

jon posted this 17 December 2012

After 28yrs. plumbing I would suggest you try using a turbo torch acet.-air best heat and clean reducing flame. A spinoff from rocket engines a swirling flame very compact very hot with jet like roar. Size the tip to the job run these tips with gas full on don't try to modulate gas flow with handle valve or a burned-out tip will occur very fast. Use good flux,make parts real clean and DON'T OVER HEAT keep testing with your solder when flows easy move along part and then quit heating. GOOD LUCK WITH YOUR PROJECT. Jon