Thursday, December 8, 2011

Home of the Braze pt. II

Okay, you're reading this backwards.
Part One is below.
For those of you coming up here from Part One, please read on.
All others, scroll down.
Anyways in Part One, you saw my first attempt at making a brazing connection.
It's a connection, that's about all I can say.
Brazing is like soldering.
In fact it is soldering and the metal needs to do the same thing.
Meaning you need to heat up both sides of whatever you are trying to braze, and let the solder/braze flow.
If the parts are not sufficiently heated, you'll get a cold solder/braze.
Using an O-A torch, you don't want to get too hot for you'll make a puka in the metal so to regulate the heat, you need to pull back on the torch a bit and not get too anxious.
Second attempt, this time on the corner of the joint:

Now we're talking!
Okay, this part was really easy as the brass just sort of knows where to go.
I mean it's not like brazing a flat surface.
Most of my corner brazes looked like this.
Boy did my head get all big.
Until I did the other side:

Still having trouble controlling the puddle.
You can use the pressure of the flame to actually move the puddle around.
Sort of.
My first concern was making sure the metal was "bonding" together, meaning I had the steel hot enough so that the braze could do it's thing.
I got a little better:

Kind of.
You can see that the lower tube didn't really get a nice cover of braze, it sort of all stayed on the top tube.
Then there was the tube that wasn't aligned very well:

There, the braze just dripped right on through.
Which is why them frame dudes mitre everything as close as possible.
Actually, I started to think that fillet brazing a frame isn't out of the question as long as your joints are set up properly.
A good one:

All in all I did five joints, each one getting a little better.
Once you figure out how to control the heat and the brazing rod, it's actually sort of easy.
What I learned in art school:

I'll have that piece of abstract art up for sale on my Etsy page soon.
Okay, not really.
What is real is that with a bit o'time and practice, I'd say building a frame at home is not out of the question.
In my browsing last night, I figured you can get a set of Richard Sachs lugs and drop outs and some Columbus tubes for around $300.
I haven't figured out the jig yet, but I'm thinking for a couple of hunskies more you'd be all set.
Next I think I'll try some MAPP gas and some silver braze I got somewhere around here and see how that works.
I've used MAPP on copper, but never on steel.
I'm sort of interested to see how it turns out.
Stay tuned.


Scott said...

Some of those don't look too bad, all things considered. It looks to me like you need to heat the tubing a bit more before you add the brass....the hotter the metal the easier it flows. It's definitely an art that requires some practice.

limom said...

Yeah, I was trying to use as little heat as possible, there were a few joints that looked on the cold side.
Towards the end, I worked it a bit more and kept the torch over it longer.
Maybe I should take a grinder to it tomorrow and see how I did.

Big Oak said...

Good luck. I'm sure you'll soon master the art and science of brazing. Looking forward to the FTPB (Flat Tire Project Bike), and how you'll paint it.

John Romeo Alpha said...

From reading the book it sounds like adding lugs and thin tubes to the brazing equation changes things up quite a bit compared to this. I'm going to spend some time online browsing frame building forums, to find out how to practice on lugs and tubes before creating a Columbus tubed, Sachs lugged, nicely painted, self-destructing crashing machine. Or just go camp out on Garro's doorstep (cold! snow! wind!) until The Master admits me into the Inner Puddle of Metal Secrets.

limom said...

Ah yes, the slip brazing.
Causing me some concern too.
Especially the part about getting a uniform heat over the whole lug.
The again I've been reading that silver flows like water so it may not be a problem getting it in there.
This is where you have and advantage, you can go and watch someone do it. I dunno of anyone here making lugged frames.
By the way, I've alread found tons of advice on Velocipede Salon.

Big Oak, don't be holding your breath on this.

Disclaimer coming up in pt. III