Need info on a good oxy/acteylene set up for brazing

[matthewsx]

Got it! Had a bad oxy regulator. LWS has a repair service but I can feel it coming out right at the brass fitting that attaches to tank nozzle - gotta be an old o-ring in there. Good news is that in my Craig's List deal the guy gave me an extra set of hoses that had a good Victor oxy reg so I just switched them out. Got a nice gas flame going late today and made a couple of the worst brazes ever botched. It seems like the 'heating moment' where everything is hunky dory is quite a sweet spot. I am getting things over red, too hot and the silver is not running it's getting red and not running or pooling. So I just will spend time tomorrow playing with pieces and trying to figure out workholding. I made a little firebrick corner is it good practice to just lay your steel directly on firebrick or should it have a heat sink touching the workpiece - like laying the work steel on top of n old piece of steel or some big washers? The guy at the LWS gave me several brass, bronze and bronze with flux coating as "samples" for $2 - nice guy. So with any luck maybe photos tomorrow - I aint showing what I made today!

Great to hear you've got it going, now it's learning and practice....

John

 

[helmbelly]

Note, the right temp for typical silver brazing alloys is barely glowing at all, you can't even see it in bright light. If your steel is noticeably glowing then you're probably too hot. The flux becoming molten and clear is your best temperature indicator.

Bring it all up to temperature as evenly as you can so that when you touch the silver to it, it wicks around everywhere by capillary action. Sometimes for a thick piece, you need to hold it at that temp for a while, to let the heat "soak in" to the thicker sections.

But don't dawdle either, the clock is ticking — you're usng up your flux — so do try to git 'er done as rapidly as you can, consistent with full penetration. This takes practice, so don't feel bad about roasting your first few trial pieces.

Stainless is extra tricky, not just because of the oxide layer, but also in the heating phase due to relatively low conductivity of SS, makes it easier to burn it locally while trying to get it evenly hot. Keep the torch moving, don't point it at any one spot. Catch the localized over-heating early and push some molten flux over the place that got too hot — hopefully some fresh flux will lift whatever oxidation you got where you overcooked the original flux. If there's ever burnt flux where you need the silver to flow, the silver will not flow there, and if some fresh flux can't clean it, then you will have to cool that part, soak the flux off, and completely clean the burnt area down to shiny steel and start again. Some burnt parts cannot be saved and will have to be tossed and re-made.

Thanks for that experienced advice. Appreciate ya. I'll try this again tomorrow. Yesterday after my oxy regulator blew out I used just air propane and couldn't get the silver to melt but the steel would get very red a lot faster than I thought. Today I got it to melt on a couple test strips of mild steel. Not well. These parts pictured are the ones I need to make. I'll just have to sacrifice a few I guess bc the 2" central stud (5/16) seems to have a lot more mass than the tube with a .050 wall so finessing them in the sweet spot at the same time is prob the trick. I've been using the torch above pointing down, and keep it pretty central to the stud. There's a lot to it I can already tell. Looking forward to next stab at it all. Thx again.

 

[helmbelly]

Question- as I work I need to re-set and piddle around so I close acet and oxy valves on the torch to save gas and then re-light when ready to resume. Is this what everyone does? Or am I living on borrowed time already?

 

[tim81]

Question- as I work I need to re-set and piddle around so I close acet and oxy valves on the torch to save gas and then re-light when ready to resume. Is this what everyone does? Or am I living on borrowed time already?

For me better not to have gas in the lines if it helps something might fall you forget stuff and it’s not good in general but that’s me. I am a newbie myself but I am trying to get it slow and steady

 

[matthewsx]

Question- as I work I need to re-set and piddle around so I close acet and oxy valves on the torch to save gas and then re-light when ready to resume. Is this what everyone does? Or am I living on borrowed time already?

It’s fine to shut off at the torch when preparing the work.

I was taught to shut off at the torch when done, then at the tanks. Then bleed acetylene first then air. But that’s just my dad.

You’ll pretty quickly get in the habit of shutting valves at the tank the first time you run a full tank down to empty by leaving one open.

John

 

[tim81]

It’s fine to shut off at the torch when preparing the work.

I was taught to shut off at the torch when done, then at the tanks. Then bleed acetylene first then air. But that’s just my dad.

You’ll pretty quickly get in the habit of shutting valves at the tank the first time you run a full tank down to empty by leaving one open.

John

LOL, I did that on a mig machine years ago. Argon mix was not cheap

 

[verbotenwhisky]

Question- as I work I need to re-set and piddle around so I close acet and oxy valves on the torch to save gas and then re-light when ready to resume. Is this what everyone does? Or am I living on borrowed time already?

Personally, if I am taking an extended break or performing an another operation between torch operations I turn off the bottle valves. The torch will bleed the pressure off the hoses but it will not completely clear the hose of gas and I leave them stored like that. I am certain someone will take umbrage with this; but this is how I have done this for decades....

 

[helmbelly]

It’s fine to shut off at the torch when preparing the work.

I was taught to shut off at the torch when done, then at the tanks. Then bleed acetylene first then air. But that’s just my dad.

You’ll pretty quickly get in the habit of shutting valves at the tank the first time you run a full tank down to empty by leaving one open.

John

Thanks - good to know -that's the same way I have been doing it

 

[helmbelly]

For me better not to have gas in the lines if it helps something might fall you forget stuff and it’s not good in general but that’s me. I am a newbie myself but I am trying to get it slow and steady

Cool nuff. I gotta admit it felt pretty good the first time I turned that yellow acetylene blue and saw that little white tip ready to do da bidness !

 

[bulgie]

Question- as I work I need to re-set and piddle around so I close acet and oxy valves on the torch to save gas and then re-light when ready to resume. Is this what everyone does? Or am I living on borrowed time already?

I love my "gas miser" aka gas saver or gasaver, which is a switch you hang the torch on. The weight of the torch pulls the lever down, shutting off both lines to the torch, but it leaves the torch valves open and perfectly adjusted. It also supplies a small "pilot light", a little air-acetylene flame that's there ready to light your torch when you pick it back up. Saves a lot of time re-lighting and readjusting the flame, perfect for repetitive work where you have to set up a part, braze it, and turn the flame off while you set up the mext one.

I actually have two of them, total luxury for a home hobbyist, but I grew to like them when I used them in production, so I had to have them for my home shop. I have one each on my acetylene rig and my propane rig.

If this sounds sketchy to you, safety-wise, well I guess it has its potential catastrophe waiting to strike, but in the 50 years I've been using one I don't remember a single scare. You just have to remember to turn everything off before you walk away. The pilot flame is there to remind you, which helps.

The two I have are

(1) a Smith, like this:


Still made, I think, though this one is from the '70s

...and (2), a really old "Harris Calorific", don't know how old but it appears in the 1929 catalog, and may have already been an old item at that time.



Since I mostly work on small stuff, I like the small aircraft torches like the Smith AW1A (well mine is actually an AW1, the precursor to the AW1A) and Meco Midget. As you can see I also like the Ultralight hoses from Tin Man Tech. The small torch and ultralight hose increases dexterity and precision, decreases fatigue. I don't braze all day like I used to, but I'm old and weak now. I can't hardly stand the weight and stiffness of those "red/green" welding hoses anymore, I'm spoiled. If you get ultralight hoses though, try to suspend them from the ceiling so they come down to you, not laying on the floor, because they don't hold up to being walked on, or having blobs of molten metal fall on them. Most people daisy-chain them with heavier hose so only the last bit to the torch is ultralight.

But I digress! If you get a gas-saver and you use propane, be aware they make a pilot light specific to propane. The flame tends to blow out if you use propane with the fitting made for acetylene. It's a 2-minute job to switch the pilot light piece. I switch mine back and forth sometimes, though I mostly stick with propane these days.