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Belltown Brazer
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Discussion Starter · #1 ·
Hi, first post in this forum.

I've read all of the FAQ's and been through thread after thread. Lot's of great info. Enough for me to buy some stuff and start to braze, without ever having brazed before.

I've got a pile of tubing, my torch, the GF rod and flux from Henry James. I have been practicing hand cutting miters and brazing tubing. I'm coming along up the learning curve. It's kind of like sailing: you can learn to do it in and afternoon, but it takes a lifetime to master.

After my first dozen joints or so, I went back through the threads to reread them with a grain of experience in my head.

Now I'm through another dozen joints, and I have a couple of questions.

I have been practicing first on 1.125 049 wall 4130 tubing, then on 035 tubing in various diameters.

I'm getting better at building up the brass where I want it, and keeping it off where I don't.

I have been brazing "downhill". Positioning the piece so that gravity will pull the brass downwards. But, applying the heat on the high side. This seems to have helped me keep the brass where I want it...but could be way off base. Do you guys braze uphill, downhill, flat...whatever?

I still get areas where the original fillet was low, so when it's filed down there are pock marks...any way to ensure I'm not getting these?

Does the whole joint have to be preheated before tacking, or just pick a side and tack away?

How many tacks per joint, and where do you put them? Sides first/only or do you do top/bottom. Do you hold the joint out of alignmet prior to tacking and let the tacks pull it into alignment?

How big are these tacks? 0.125", 0.25"?

Do you aim when brazing to make the fillet flat or concave? How big shoreline to shoreline? 10X the tubing wall, or 0.5", or whatever floats you boat that day?

Alright, I've gone on long enough. Thanks for any advice you might have.

B
 

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7,491 Posts
A few semi-answers

I can't answer most of your specific brazing questions, because I'm not the brazing expert, but I can tell you that for tacking, 4 points (as evenly spaced around the joint as possible) is generally the rule of thumb. I do 3 on some things, though, and that seems to work out fine as well. Your miters (and brazing sequence) are what will determine whether the final structure comes out the way you want it, so the tacks just need to be enough to hold everything in place.

FWIW, when I do fillet joints (very rarely, usually for braces and canti bosses and such) I've found the following to be helpful:
-Preheat the whole joint (get everything glowing a tiny bit) before applying any rod.
-Braze slightly downhill.
-Learn when to pull the torch away and let the heat of the puddle do the work. Once you've preheated, use as little flame/heat as you can and move slowly.

Steve Garro often posts here, he may have more ideas for you. Or other fillet folks could chime in. Post some pictures of your efforts for us, eh?

-Walt
 

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hey, man. i'm retiring from cyber mentoring for the most part. i'm convinced that i cannot teach anyone technique over the web now. i've logged several thousand words trying both here & esp. at FF. it's in the archives. but, here's a pic. check out my blog, ther's 1000's of brazing photos. happy building! steve.
 

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Belltown Brazer
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693 Posts
Discussion Starter · #5 ·
East Hampton/New England Steel 29er hardtails...yea...eventually. The next step after pure practice is kids bikes for the younguns. Then one for me...for sure I've broken enough bikes that I qualify for product tester status. We'll see how far I get. Depends a lot on how much time I can steal away from the circus....though it only is as far as the basement.

Not sure why, I've been talking for 20+ years about building bikes...something this fall said it was time. Perhaps I've finally recovered from the Caddy restoration...that nearly wiped me out.

Not much to see yet (but a few dozen practice joints), but you're always welcome.

Enjoy the holidaze.

B
 

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Hi folks- I mostly lurk over here every couple of months, but thought I'd add a bit.

Filler rod goes were there is a clean surface and heat. Along with the mechanical cleaning, the chemical clean of flux is pretty darn important. Defiantly put it in your tubes.


In this cutaway you can see an internal fillet about the same size as the external fillet. Mostly due to heat control and generous fluxing.
 

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Steve, your advice has been very helpful. I know you get tired of typing it, but don't think it was in vain. I appreciate it.
To the OP, check the link to my Blog in my sig. I have some of my tips that I won't bother retyping. For the record, I braze slightly uphill. With proper heat, the brass should go where it's clean. If you are going DH, the puddle will fall on the floor before it is liquid enough to get sucked inside the joint and form that sought after internal fillet.
 

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coconinocycles said:
hey, man. i'm retiring from cyber mentoring for the most part. i'm convinced that i cannot teach anyone technique over the web now. i've logged several thousand words trying both here & esp. at FF. it's in the archives. but, here's a pic. check out my blog, ther's 1000's of brazing photos. happy building! steve.
Your web advice has helped me greatly, Steve. You also taught me how to ask the right type of questions, usually at a time when I was ready to make the next step in my abilities but did not know how to get there.
 
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