Silicon Bronze MIG brazing

More of an art than a science - discuss metalworking and welding here.



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PostPosted: Wed Dec 26, 2018 10:20 pm
wire size .030, I never use the Auto Set, I always push bead with gun almost perpendicular with a slight tilt backwards.
I have read a number of times that the gap is a must and the only way to allow the the braze to flow underneath, it sounds like you are recommending to melt through the parent material to get the braze to flow to the other side?



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PostPosted: Thu Dec 27, 2018 7:30 am
I Tig weld Silicon Bronze, When I do I want a Tight fit.
https://www.youtube.com/watch?v=wf-Cq5eQmt0&t=198s

Why you would use a Gap with Mig welding and a Butted up joint with Tig welding is beyond my knowledge. If I had some silicon Bronze wire for my Mig I would still try it Butted up tight and look at the results. I think I included some I car welding examples I am not an I car fan myself but if thats the way they say to do it it must be right they are good for teaching guys correct ways to do things.

Most all the videos on you tube demoing Silicon Bronze show to use a gap and a Large stick out as well.

Since I got my Tig welders I very rarely ever fire up my Mig.

https://www.youtube.com/watch?v=wf-Cq5eQmt0

Big gap short stick out
https://www.youtube.com/watch?v=CaUkzcdHmws
https://www.youtube.com/watch?v=jBDipQpOeR8

There are a lot more at any rate I would not let the gap exceed metal thickness
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PostPosted: Thu Dec 27, 2018 1:52 pm
Give a man some settings and he welds for a day, teach a man what the setting does, and he welds what he wants.

Like the guy who say's, my welds usually look better but it's not the machine I'm used to. Or they would have looked better but I had a hard time dialing it in? Maybe, I'm having a problem can you tell me what I'm doing wrong?

Instant gratification. Seems it's what we want? All the pleasure with out the pain. I tried to share in the pain. The pain of learning. What this does, that does and how it has an effect on something else.

I'm going to briefly talk about the gap. What do you do if it is to wide? Can you adjust welding parameters to compensate?

Shielding gas was mentioned. How much is too much, and how does to little effect things?

Where does volts and WSF fit into the picture in melting that skinny wire? I commented about the big old ball at one point. Well...is it getting smaller now and why?

I posted a couple of my drawings. Did you look at those closely? If you study them, you might find a few answers to ease the pain of learning.
If you did what I suggested, you might also discover they start to make sense?

In doing what I do, I tend to remove a lot of metal from those who were taught "settings" to weld. The do as I do crowd. I get it, it's easy that way. Your still sticking it together, and with a bit of grinding, a bit of filler, good to go.
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While anyone can weld, or paint cars for that matter, the fella who "knows", does it better, more consistently, uniformily, and understands why, because education put into practice yields better results.
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For everything else is grinders and sand paper to remove imperfections that could probably have been avoided with education, the knowledge that goes with it, and practice?

Judging from your last picture of three beads on coupons, things are improving. Fantastic. Maybe it was as simple as more gas shielding? I'm sure with a excessive stick out it had to do something of benefit?

"Your welding Technique should be the same as used for regular steel welding"

Those reading may not appreciate the soundness of this advice, but in order to develop technique it takes knowledge. And knowledge must be applied in practice.

I liked the first weld of the three. What I'm not sure about is the color in between the weld and area protected by shielding gas? What's that about?

Did you do something different between them, because they look different in appearance? Went from skinny to plump in the middle one? And the third one. Where you squeezed and released the trigger. Maybe release sooner?

You mentioned early on a solid 4. I mentioned it was a good number. Pick a number between one and 10, 4 does sound good.
Now...if I was going in for surgery...criminal charges, trusting my life in the hands of others, I'd think 7 would better my chances.
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Anyways, you discover something in your practice I'm all ears.

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Practicing doesn't make perfect, but it gives repeatable results. The old adage of not learning by past history and repeating it, also holds true.
Look at what you did and ask why? Then ask what if? And remember 7 is obtainable.

Happy New Year.



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PostPosted: Thu Dec 27, 2018 6:32 pm
Noel,
I keep looking at your drawings and I get some of it, they look like they should be easy to figure out but maybe the more I practice the more they will make sense. I printed them out and pinned them up in the shop.
"I liked the first weld of the three. What I'm not sure about is the color in between the weld and area protected by shielding gas? What's that about?"
That colour in the middle is me being cheap and lazy, I cut up some old painted sheet metal and cleaned the paint off of the edge where the weld would be.

I shall endeavor.

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PostPosted: Fri Dec 28, 2018 4:18 pm
I had been pondering buying a roll with this discussion. I have it in GTAW rod form , just not spooled wire. Although I'd find very little use for it, I made the calls and discovered availability and cost were issues. Few had stock calling the bigger suppliers, although they would get it in for me, with a the 10kg spool price at $200cdn+ GST (gouge and screw tax), I nixed that in a hurry.

My drawings when looked at closely hopefully encompass the major variables to the process, but also to some degree the effect they have to the process? Admittedly, I have an encompassing talk that usually went with handing them out that your not getting?
Bummer eh?
What effect does an increase/decreasing in wire feed speed have? What does it effect, how and why? That's easier to explain verbally, or drawn on a white board for explanation, but it was a start and avoidance to lengthy typing.

Simply stated, was the car going to fast to stop? Inertia carries things forward...Maybe a light car would have stopped in time? Maybe the cars braking surface was to small for the size of car? Cheap pad material not producing a good friction grip to the rotors? Bald tires not gripping the road surface? Maybe not enough pedal pressure due to a weak master cylinder leaking at the seals? Or did it just not stop in time?

I hope you understand I was trying to be helpful. Switch back to a solid wire and mixed gas. Cheaper, more affordable to practice with. Experiment. Then take what you learned, discovered, and apply it to what you see happening with the other wire.

I just received a call back from another supplier. $188.86 + GST for a 10kg spool, two weeks to get in. I doubt I'll buy. I get by fine with out it and I solid wire everything.

You are however on the right path. All knowledge does is allow for greater choices to be made, or more varied responses to circumstances being presented. Plugging a hole, filling a crack, stick two pieces together to make one. You've shown you can do that. With confidence, repeatability, consistency...working on it.

Getting past that and with deeper thinking, why? I'm recalling from memory door skins and in the middle?
Expecting better results? Improved mechanical or chemical properties? Appearance? Joint design? Warpage/distortion control? Ease of application or clean up? Cost? My favorite is just because I can? I usually follow that with, but should I?

I'll mention copper chill strips or backing. Suck that heat away. But controlling it, is being in control of the welding process.
I'm not trying to say don't, or you shouldn't, or you can't...just getting you asking why?

Those drawings..."they look like they should be easy to figure out". You see something in those drawing that bring about a question, you ask it. I was the guy who drew them, I'm the guy who can answer questions on the topics presented. :shocked:

On a personal note...I don't want to blow $200 on a spool of wire I'll never use, but I mentioned my favorite for a reason. Because "I still can" could be a good enough reason?
Happy New Year.
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PostPosted: Fri Dec 28, 2018 10:04 pm
A 2 lb. reel is $36 bucks.
"Switch back to a solid wire and mixed gas. Cheaper, more affordable to practice with."
I know how to Mig steel, that's what's bugging me, I thought I would pick it up Mig brazing quicker. But I'm starting to get a feel for it and really appreciate the help you guys have given me.
Thanks

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PostPosted: Sat Dec 29, 2018 12:50 am
With all due respect, and no dissing of your abilities, that's not the material you were trying to weld with the silicon bronze? That material thickness is no where close to 18gauge? Do those welds you previously did with solid wire and let's have another look.
And to be fair about it, so will I.
Write down your setting and show the back side as well. It's about learning. No harm no foul, and remember I'm going to show you mine.

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You'll notice these were taken 2006. It's what, 2018 now? Seems like a long time ago? Anyways, the back story is that it was called a start to a hammer dolly project to crown the panel uniformly. I never had time to practice that far, but used it later to practice different patching methods.

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In another post I mention a 84 Van needing rust repair. Summer of 2007 was a hot one. I had a panel flange tool with a hole punch, need to use it some where or eventually for something.
Well, this was the piece I used to practice fast and simple.
It was sitting around half beaten into a low crown, I was never going to finish. It was to darn hot for me to be welding, and I need to use my favorite excuse for everything.
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This shows the back side of the plug welds. I mention again it was hot out. I don't do sun shine.
So after spending a couple hours dicking around I decide to use panel adhesives instead. of welding. One spray can of 2k epoxy primer and a off the shelf spray bomb that looked close for color match. Lol. It's a work in progress waiting for a custom paint job. But it takes me places.
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So far, it's holding up well.

2018...62 years old. You have some stiff competition here. You up for it? Lol. Poke, poke. Who knows...maybe we'll start something?

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PostPosted: Sun Dec 30, 2018 4:48 pm
1/2hr. That's how long it took. In and out of the garage in under an hour. That's a testimony to three things.
Knowing my garage. Knowing my way around it. And knowing my equipment.

I thought all this time it was a 140? Turns out it's not?
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I set things up saying this looks about good.

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Top right corner is a small scrap that I gave a zap to and said I can work with it, I started tacking edges.

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Now...the only thing that was changed, was length of stick out, short to long. 1/4 to 1/2".
Admittedly, a slower travel speed was required, but minor, and I could have done things more scientifically but the point was, try one thing at a time and see the results. For give the inconsistencies, not to make excuses, but it had been a while and as you see, I quickly got up to speed as I did a few more.

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Being a lazy guy I was going to call it a wrap thinking I did my small part to push the learning and realized all those other pieces tacked together looked kind of barren. For the sake of learning I bumped voltage to two and repeated. That little squiggly at the end, that was me showing off. :happy:
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Can't say I got everything done I wanted to accomplish or had planned to do/get done in 2018, but this was going to be one I did. Happy New Year.

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PostPosted: Sun Dec 30, 2018 7:29 pm
Sooo? Shorter the stick out the better - all else being equal?
Sent by the random thoughts from the voices in my head...

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PostPosted: Sun Dec 30, 2018 9:30 pm
OldFatBald wrote:Sooo? Shorter the stick out the better - all else being equal?


No...what I'm saying is I did three welds and the big change was stick out. Then I adjusted the voltage tap up one setting and repeated.

With allowances for old blind and shaky, each increment of length had an effect on the heating of the wire, droplet being formed, force it's transferred, heat it imparts and the depth of penetration/fusion, HAZ crap, and surface appearance for lump and flow, although lump and flow are intertwined with gun inclination and speed of travel.

My words not someone else's. Most screw up torch brazing because they get it too hot. Using a silicon bronze GMAW wire, is no exception. Buddy in the pipe weld video previously linked, prime example. Hate to be a critic but...
I'm saying practice, experiment, think. Discover what that knob and dial do. How the length of stick out effects things, what the shielding gas changes.
You could also ask, how big in size does that weld need to be? I wasn't burning any holes? Not much splatter. Looks like I almost burnt thru as a few showed a melt and oxidize in spots I moved a bit slow?
Sure...it's just mig welding? Anyone can do it. And they can. They can also do it better.

My way to instruct getting better is sequential. But I've been know to just blast away.

But...lengthing the stick out will stiffen the arc, causing it to narrow, decreasing the frequency of droplets as well making them smaller/firmer, up to a point...the next question should be, what the heck happens when you reach that point?
Also, shortening the stick out results in less heat loss due to resistance so the droplet becomes hotter, wetter, softer.
Here's food for thought. 18ga. material. If you do a weld, and the surface gets ground flush, where does it end up?
Higher the voltage the wider the bead. Shorter the stickout, the wider the bead.

I didn't adjust or mention WFS. Sequential...one thing at a time.
But if you lap or butt two pieces together and your punching thru or burning holes, something should be changed or corrected to prevent it from happening. Reducing voltage is one way to do it.
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