Sunday, February 26, 2012

Sunday Early Edition

Boy, this is embarrassing.
So embarrassing that I don't even want to show you the pictures.
I mean they really look bad.
If you, the reader, remember yesterday, off I went to try and do a braze job on a frame.
Well braze I did.
Sort of.
First, the excuses.
The pipes were not mitered.
Apparently, this bicycle, a tandem, was actually two bicycles that were put together.
Rather nicely I might add, except that on the area I was working on, the rear triangle/seat tube/top tube junction, the tubes were just sort of stuck together end to end.
Which meant gaping holes where I was trying work.
Someone else had already worked on this area, old braze was everywhere.
The person with the frame had tried to remove as much of the old stuff as possible, but it was pretty ugly.
Sort of hard to see, but here it is, covered with flux before I started:

If you squint yer eyeballs, you can see all the residual braze still there under the flux.
It wasn't pretty.
So a brazing I went.
Most of the joints I worked on were pretty bad. There was so much braze there all I had to do in some places was heat it up and move the brass around.
Or so I thought.
Too much heat and the braze just dripped right through the join as there were rather large spaces between the join areas. In some places more than 1/8" between the tubing.
So I just did my best:

This is actually the good side.
Again if you look good, you can see the two different colors of the old and new braze all mixed up.
Really, this side went well I thought.
Besides the big balls of braze hanging down all over.
If you remember Brazing 101, you know that braze is not a filler material, but today it was.
I was also able to see and distinguish a good braze from a bad one, the brass gets all shiny sort of like soldering and spreads compared to a cold braze which stays sort of dull looking.
Here's the other side, which I have to say looks really really bad:

Keep in mind, only half that braze is mine, most of it was already there.
This was the side which had the gaping holes.
Very difficult to fill.
There was also a crack in the seat tube on the top which I tried to fix.
I got to see the capillary action though, using the old braze already there and just heating the area that needed to be filled. The braze just follows heat and flows towards it.
In retrospect, I wish I was able to move the frame around, upside down and upright and side to side, since the braze is subject to the forces of gravity and flows downhill.
I think that would have helped a lot.
Being able to move the frame around I mean.
The good thing is, I learned more about controlling the heat, I mean I didn't make any pukas in the tubes!
The distance of the torch to the surface is important, as is the amount of gas you are pushing.
As for working with lugs, this wasn't a very good lesson for the fluxing temperature of silver braze is a lot lower than brass, and you use more of that capillary action to fill the connections.
Still, a good practice session.
I just wish it looked a little better.
Okay, a whole lot better!
On the other hand, I wasn't working with properly dressed and mitered tubes, so it is what it is.
Now I really want to try and fillet braze some real tubing.
You know, to test my Jedi skilz.
Okay, I'm still a Padawan.

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