Made in China - fixed in America

[jfcayron]

There I was, installing 220V in my workshop, when my neighbor walked in saying "do you think you can help me?" and shows me this hub.



It is part of a Mongoose bicycle equipped with very fat tires. To accommodate the wider wheel, the manufacturer created an extension to the regular-sized part.
The extension is welded to the rest, but in this case the weld is not on the seam, it is right NEXT TO IT. Kudos for quality control!
With maybe 20 thousands worth of filler holding the 2 parts together, the inevitable happened and the joint broke.
According to my neighbor, the owner's forum is full of reports of the same failure. Not just one miss, but a whole batch of them.

The fix was fairly simple:

- turn off the existing weld

- bevel the joint

- braze both parts together

- turn the joint smooth



Don't you just love a grateful neighbor?

 

[Andre]

Love the title of this thread!
Nice, simple fix. Good job.

 

[wquiles]

Nicely done :thumbsup:

 

[rdhem2]

Very nice. Good job all round.

 

[desbromilow]

why use all those washers in the brazing photo?

can you please explain what that part of the technicque was about?

thanks,
Des

 

[Andre]

why use all those washers in the brazing photo?

can you please explain what that part of the technicque was about?

thanks,
Des

Probably to keep it straight. When you braze the opposite side, it "lifts" because you add metal under the seam. The washers were probably to bend it straight (opening the gap even all the way around) to braze the other side. But it's just a guess.

 

[jfcayron]

why use all those washers in the brazing photo?

Good catch.



The rod is needed to keep both parts together tight while brazing.
Why so many washers? Because it is not all-thread, just the ends are threaded.
The washers are just there to take up the slack.

It does not get any lower-tech than that!

- - - Updated - - -

Probably to keep it straight.

Correct, but you would need just a couple of washers. The rod is too long, hence the stack of washers.

 

[barrydc1]

Any reason in particular that you chose brazing over welding? Are the parts different materials? Just wondering.

 

[jfcayron]

Any reason in particular that you chose brazing over welding?

My stick welder was temporarily unavailable, and Welding with O/A would have put too much heat in the part, which appeared to be hardened.
I thought brazing was safer in that respect.
The parts telescope, so brazing should be plenty for that application.

I definitely would have stick-welded given the option. (I would love to own a TIG welder, but I don't).

 

[barrydc1]

Great project, and thanks for answering the question. I'm very new and not very good at welding yet. I have never tried brazing. I have a stick and a mig welder (and would LOVE to get a TIG as well). I've gotten a bit better at both after lots of reading, and not quite enough trial yet, sooo... I love to see projects like this that combine the two and hear how and why you did things. Thanks again for posting.

Barry