Brazing thin to thick - technique, tip size or fuel?
 

Sorry if this is here somewhere. I did search and read quite a few threads, but could not locate the answer.

I have a Berzomatic TS4000 MAPP torch. I am no pro, but am OK at common rod and tube joints (8 joints out of 10 turn out as expected).
I have been doing all stainless. I use 45-56% silver with Stay-silv.

I have two things I cannot nail down.

The first is running around the edges of thin sheet stock (20/22ga) to pipe or rod (run lengthwise). This would be filling in between the frame rail, and rocker with sheet stock attached continuously or in points along the edge.
The thin stock ends up glowing read before the pipe or tube even gets clear and hot enough to pull silver solder.
And I end up have to move an inch or two down the edge to do the next joint because of sooting.

The second is attaching most small stuff to heavy gauge items.
I have some nice rolled stainless trim pieces I want to use as sliders over the rockers. These are approx 14ga. and 3/4" x 7".
Here the thick piece pulls so much of the heat away, that by the time the joint area is hot enough to pull solder, I have cooked the small piece I was trying to attach.

I do not know how to weld, and am not ready to spend the funds on the equipment for it. But I have a local shop that I send enough business to through work, that will tack some of this stuff for me, pretty cheap.

Is there a better technique for the two different joints above?
They are clean and sanded to start, fluxed, and clamped in place.

Is it time to jump to a Smith MiniTorch? Is the small, controlled flame size the fix?
Can you run a smaller flame along the sheet stock and get an almost continuous joint?
I'm assuming a small oxy-mapp flame can get more of the immediate joint hot on thicker material?
Is the setup for the throw-away MAPP + Oxy OK? Is this the model 20-1014 or 1015?

thx

Re: Brazing thin to thick - technique, tip size or fuel?
 

Well, I don't know how much help I am because I too have problems with thick to thin brazing.. I always end up burning up thin sheet metal when I'm trying to stick it but, Instead of trying to figure it out.. I just end up Mig welding it.
I find that If I preheat the area I want to Mig, it'll weld the thin stuff a lot easier.

I would try the smaller tip size for more concentrated heat. Then keep heat on the thicker of the two pieces and flow the heat over to the thin piece until you think you have equal temp's on either piece.. then try to apply silver.
It may take some time to get equal temp's but, you can always take heat away or move it around until you get what your looking for.

Re: Brazing thin to thick - technique, tip size or fuel?
 

what he said. I don't do much thin plate to rod for just this reason but I do rod and tube to each other and to solid stock, and to me, the trick is accuracy with the heat source. As fine a flame as you can get and get the thicker heated first and then carry the heat over to the thinner. I also find that a tube to tube or rod to rod joint with a Ace Hardware MAPP torch is fine but when trying to do the more detailed work i use an Oxy/Acetylene setup with a small tip and very controlled flame. If you can afford one, the Smith Little Torch is great for this.

Well if you are trying to use the safety silv as filler you need to get your thicker piece hot first and the heat should transfer enough to the thin stuff an instead of getting it red hot kinda put your brazing rod in the flame and after the melted braze is on your joint kinda work it with the heat until it starts to break down and smooth out... It's all about heat control.. But that's the best way I've been able to fill a gap or braze say 1/4 solid rod to 3/16 tube .. If I didn't make enough sense let me know and I'll try to explain better or take a video I'm pretty dang good with the 45.. It's alot cheaper and quicker to get ya a descent little 110 welder from lowes.. After you buy 4 or 5 tubes of 45 or 56 shoot you could've got a cheap welder for that price..


J-bird

Re: Brazing thin to thick - technique, tip size or fuel?
 

heat the thicker part and angle the heat away from the thinner part and more towards the center of the thicker. allow some of the " bubble " of heat to start heating the thinner part. the solder should start to wick its way to the thinner right after the flux paste has gone clear. it is possible to be getting the thinner part too hot and burning off the flux.

honestly i can say i had that same torch, it sits under my bench now. the patented " swirl tip " torch head was too fluffy of a flame for my technique, if you can understand that. i didn't like how it was a soft flame. i went to my pop's house and grabbed a simple bernzomatic pencil tip torch from 1967. this thing is as basic and no frills as they come, but the flame that comes out of it is solid and a nice chisel tip blue point that i can accurately aim and burn up shit because i'm still a noob.

go pick yourself up a yard sale find pencil tip torch head and give it a shot. you might not have the same opinion as my findings, but it is something that worked for me.

unless your going to buy a welder, in which case i can send you my work and i can continue to be lazy but still get stuff done.
"thumbsup"

Re: Brazing thin to thick - technique, tip size or fuel?
 

yeah that head on that torch throws a hugh wide flame :roll: ....you need a small pin point flame to do work like that........bob

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Re: Brazing thin to thick - technique, tip size or fuel?
 

Thanks for all the responces!

I would like to get a Smith mini torch, but might have to save some more pennies.

A buddy has a Worthington WK7601i. They make different tips for his torch, including a WB0201i Pin Point Burner. Wonder what the flame looks like? But only place I can find it is Ace for $75!?!?

What model of Smith is everyone using with throw-away bottles?