OT: Welding question

[J Miller]

My son left a small BernzOMatic welding unit when he ran off to AZ.
I watched him use it to great results when we were working on my Uncles 27 Chevy.

Anyway I may need hotter flame than a regular propane torch to remove the front sights on two Ruger Blackhawks, so I plan to use this.

Now this is the unit that takes a propane and an O2 cylinder.

The instructions are as follows:
1: Connect cylinders to proper valves hand tight.
2: Open propane valve 1/16 turn-light with sparker-adjuster flame to 4".
3: Open oxygen valve - obtain neutral flame.
4: Adjust flame as necessary.
5: Turn Oxygen off before turning propane off.
6: Disconnect cylinders when not in use.

OK, this is all self explanatory except the obtain neutral flame part. What is a neutral flame?

Next question is: I've been told you can use MAP gas in place of propane in this type of welder for a hotter flame, is this true?

TIA

Joe

[fatoldfool]

The neutral flame won't have red or yellow. Sorry, can't answer about the mapp, all I have ever used is acetylene/oxygen.

[flatnose]

Joe,
You can use MAP gas for a hotter flame. Propane will do it, but it takes longer to heat.
To get a neutral flame, fire up the propane, and keep adding Oxygen until a central cone forms within the flame. Only add enough oxygen to reach this point. The hottest part of the flame will be at the tip of the central cone.
Maybe there is a demo on you tube????

[flatnose]

Here ya go, just use the same principle.
http://www.youtube.com/watch?v=zVOZpUFFRNg

[Wind]

Joe - Maybe this will help. Best regards. Wind

[J Miller]

Wow, thanks for the tips and the YouTube link. Is there anything that's not on YouTube???
Wind, thanks for the pic, it does help.

Joe

[JOHNNY WACKO]

Never let the flame go away from the tip.That when there is about a 1/2" of clear space between the tip and were the fire starts.If so back the gas off a bit.It will pop and blow out real easy if its like that.

I just watcher the video and if your using propane you will not get a flame like the Guy in the picture because propane is not as hot.It works great for cutting but is a bit fussy for brazing.And i brazed a lot and had to get a different nack for propane.

[mescalero1]

Wrap those barrels with a heat sink right behind where you are working.
You have a son?

[J Miller]

Wrap those barrels with a heat sink right behind where you are working.
You have a son?

Heat sink ... I guess I'll have to get some of that stuff.

Two step sons one step daughter. 36, 40, 41 ... gads I'm getting old.

Joe

[mescalero1]

Ya mon.

[Rimfire McNutjob]

Heat sink ... I guess I'll have to get some of that stuff.

You can buy heat barrier pastes and stuff, but a damp towel will often do the trick depending on what you're doing and for how long.

Is the sight brazed to the barrel?

[piller]

If you keep the heat on there for only a few seconds to less than 5 minutes, I agree that a damp towel will work as a heat sink. In case you don't know, the heat sink will help to prevent the barrel from losing its temper. (Yes I know it might still get mad about having been flamed) Without the heat sink, you might weaken the barrel. Have fun and be careful. I am looking forward to seeing pictures of the project.

[J Miller]

Heat sink ... I guess I'll have to get some of that stuff.

You can buy heat barrier pastes and stuff, but a damp towel will often do the trick depending on what you're doing and for how long.

Is the sight brazed to the barrel?

I'm not sure what Ruger used to put their front sights on, however I believe Winchester did braze the front sight on the Trapper. There is a bronze colored line around the joint of the front sight and the barrel.
I'm going to try to remove the front sights from the Rugers with a torch, I've read reports from others doing this. But the Win I'm going to grind and file off. I have no intention of trying to torch it off.
The silver solder I'm going to use melts at 400 something degrees and has an 8000 pound yield strength, so that won't hurt the barrel and should hold nicely.

If you keep the heat on there for only a few seconds to less than 5 minutes, I agree that a damp towel will work as a heat sink. In case you don't know, the heat sink will help to prevent the barrel from losing its temper. (Yes I know it might still get mad about having been flamed) Without the heat sink, you might weaken the barrel. Have fun and be careful. I am looking forward to seeing pictures of the project.

Over on TRF one of the members did a thread about just this. (I was going to reread and post it but I can't get on TRF right now)
He said to concentrate the heat on the sight, not the barrel. A couple forum gunsmiths have said the same thing. So that's what I'm gonna do. Will have the wet rags handy as well.

As for taking pics that's gonna be a problem unless I can coordinate this with my spouse. Hard to work on things and take pics at the same time.

Joe

[fordwannabe]

Joe wrap the cold wet towel around the barrel just behind the area you are working on, the evaporation of the water will dissipate(however it's spelled) the heat to a degree but you still gotta be careful. Good luck Tom

[KCSO]

Ruger front sights are brazed and have a locator pin. The Mapp gas torch will do the job, but buy extra cylinders especially Ox as it goes fast.

[J Miller]

Ruger front sights are brazed and have a locator pin. The Mapp gas torch will do the job, but buy extra cylinders especially Ox as it goes fast.

KCSO,
Thanks for the info. I'll pick up some extra cylinders before I get started. I do remember how fast the oxygen went when we were brazing the holes in the oil pan of the old 27. We got real good at preparing our work before we even lit the torch.

Joe

[Bill_Rights]

I view of the locator pin, you should clamp so the barrel is upside down, hoping the sight just falls off with gravity when the solder loosens. Still, it could wedge on cock-eyed and not just slip off. Have a pair of needle-nose pliers handy to tap and yank the sight off.

Despite what someone said, above, you CAN'T just ONLY heat the sight. The barrel itself has got to get hot or the solder won't melt uniformly. I like to pre-warm the heavy component (the barrel), along with the sight base, for a few minutes under "low power" flame. Usually you have next-to-zero adjustment of flame intensity on these amateur torch rigs, so that means you have to hold the flame farther away (3-4 inches), keep it moving and evenly heat all sides, top/bottom and farther along the length of the barrel than just the sight base. While you're doing this, keep dripping a little water on your wet rags that you've got wrapped around the barrel, 'cause the water will come off as steam. The rags should be 2-3 inches down the barrel from the closest point on the base of the sight. During pre-warming, run the flame right up to the rag but not on it. Don't dwell the flame near the rag; dwell more out near the muzzle.

The goal of prewarming is to get the barrel right under the sight base to ~ 80% of the temperature of the solder melting point, say 300°F if the solder melts at 400°F (but, of course, you can't measure this so you go by feel). After a few minutes of pre-warming, concentrate the flame more and more on the barrel at the sight base and the base itself. Add water one last time to the rag and GO FOR IT. This is kinda do or die. Heat the sight base with as much as you've got and still keep the flame moving from end-to-end of the base and jumping from one side to the other. Don't worry if some flame jets around the barrel at the sides of the sight base - this can't be avoided - KEEP THE FLAME MOVING.

Have a second (not-so-) damp rag ready...

At some point, the sight will drop off (It would be great at this point, and ONLY AT THIS POINT, to have a second person pulling gently straight away on the sight, gripping the sight blade with needle nose pliers.). Once the sight is gone, keep the flame on the barrel under where the sight was until, quick like a bunny, you whip the flame away and swipe the barrel where the sight was hard and fast with the second damp rag. [Remember, earlier you CLAMPED the barrel securely.] This will wipe away the solder that stayed behind on the barrel, clean as a whistle. Else, you end up filing and sanding for half an hour to remove this solder, plus scratch up the surface of the barrel all around where the sight base was.

Let air-cool slowly.

There are even more steps for soldering something on, but the heating and heatsinking routine is the same.

[piller]

Bill-of-Rights---Well said. I am printing it off because I might run into someone else who wants to do a similar job, and this is well written and easy to follow. My directions don't always come out like this.

[Rimfire McNutjob]

Keep in mind that if it's brazed on, you're going to have to go way past 400 degrees to get it off. I would imagine the Ruger factory would have used an induction brazing heater like below ... either manually or robotically. You can see how it would be easy to heat the end of a barrel within the coil and apply the sight.



No, I don't have one. I just have a common oxy/acetylene setup with a Harris torch. Mostly I use a TIG welder for hobby stuff. The last thing I had to braze was a copper fitting to a stainless flex tube. I had to use Sta-Silv 56% to do it too. Because I'm not really that good at it and the high silver content makes brazing dissimilar metals easier for hobbyists like me.

[J Miller]

Keep in mind that if it's brazed on, you're going to have to go way past 400 degrees to get it off. I would imagine the Ruger factory would have used an induction brazing heater like below ... either manually or robotically. You can see how it would be easy to heat the end of a barrel within the coil and apply the sight.



No, I don't have one. I just have a common oxy/acetylene setup with a Harris torch. Mostly I use a TIG welder for hobby stuff. The last thing I had to braze was a copper fitting to a stainless flex tube. I had to use Sta-Silv 56% to do it too. Because I'm not really that good at it and the high silver content makes brazing dissimilar metals easier for hobbyists like me.

Well, I wondered about that induction type welding. I thought it might have something to do with robotics. That would explain the high number of crooked sights. No human involvement.

We'll see. The .357 Ruger's front sight isn't even totally attached, so I'm hoping for easy removal.
The .45 Ruger might accidentally get it's barrel shortened to 4 5/8". That would make the job fairly easy.
I'm already planning to manually remove the sight from the Winchester. That barrel is just too thin for me to try to torch it off.

Nice pics though. I wonder what that induction welding does to the heat treating of the barrel steel?

Joe

[Bill_Rights]

Rimfire McNutjob might have a point:

Keep in mind that if it's brazed on, you're going to have to go way past 400 degrees to get it off.

I have done a good bit of silver soldering and brazing, and usually the temperature of the metal is such that the metal glows dull-red, if not outright red, or even orange. If the metal starts to glow, I think the temperature is ~ 600°C = 1100°F. Could be 500°C = 930°F. I do not know if this is hot enough to affect the tempering of the barrel steel. Sounds pretty close, though. Maybe the tempering doesn't matter that much out near the muzzle? Most of the real explosive pressure is in toward the firing chamber, and I think the mechanical wear is greatest there too, where you're accelerating the bullet from dead stop with no spin - once its spinning, out near the muzzle, I think the rubbing will spread evenly all around the bore and not bear hard on any one place.

I guess you could re-temper the steel by quenching it while it is still hot (dunking in a pail of water), BUT there is a whole science to tempering and you don't always want to quench super-rapidly, and it matters what temperature you start cooling from, etc. I can't help with this.

Piecing together the evidence, no wonder the manufacturers attach sight ramps with screws now-a-days. You can drill and tap the holes while the metal is still soft, then temper it. You cannot (I don't think (I might be wrong)) braze on a sight, then temper the barrrel steel, because the pre-heat temperature for the tempering would ruin the braze. In actual fact, the modern way is the better way, from a metallurgy point of view. It only matters if your design pushes the limits of the material to where it has to be well-tempered, though. Many older designs were just conservative (over kill) and built plenty heavy, to remove material-variability risk. Witness our cars from 50 years ago.

[Ben_Rumson]

The real fun could begin when the polished interior bore oxidizes and scales up after being dull red or red or orange...If it was brazed..Soft soldered you might get lucky and have no scaling..Keep the heat on the sight...

[jennydinc]

MAPP gas (short for methylacetylene propadiene[citation needed]) is liquefied petroleum gas (LPG) mixed with methylacetylene-propadiene.
The composition of the gas is: propyne 30%, propadiene 14%, propylene 43%, propane 7%, C4 (isobutane, butane) 6%.
he gas can be used in combination with oxygen for heating, soldering, and brazing due to its high combustion temperature of 2927 °C (5300 °F) in oxygen. In this connect you can use it for hotter flames.