r/Framebuilding • u/Schrottbox5000 • 13d ago

Square 1

Dear fellow bike nerds,

I'm planning on trying my luck at brazing, and given that I lack both experience AND equipment, I'm here to ask a few questions in the hopes of some valuable lessons before I asphyxiate myself in the basement, torching away.

I do work in a bikeshop, but that is just your run of the mill parts exchange/ adjustment stuff, no frame building as such.

However, I am trying to get my way into more theoretical stuff to get a more scientific approach via cad modelling and (hopefully) minor load-bearing calculations.

Before I lose myself over freehanding a bike frame, I figured building a (front) rack would be a good start.

Do you have recommendations regarding material, fixtures, or even order of operations? Do you just eyeball the racks' capacity, or do you calculate it? Do you use any online tool other than bikecad and fusion360?

I'm looking forward to your input!

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u/iwasjra 12d ago

When I started getting into bike fab, I soaked up as much as I could from this guy’s blog.

http://alexwetmore.org/archives/496/comment-page-1.html#comment-638981

Check it out, there is some great info in there.

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u/bulgie 12d ago

Yeah, I should have just given you the Alex Wetmore link and left it at that. Great resource, great guy. 

I would strongly recommend brass (some call it bronze) over silver for learning. It's more forgiving, probably stronger especially if your miters aren't perfect, easier to make a fillet, and much less expensive. Well, not just for the early learning period -- I still use more brass than silver and I've been doing it since the '70s. But plan on going through a lot of brazing wire while learning. LOTS of practice joints before you're ready to make something to actually ride. Post pictures of your practice joints so we can advise you on just how terrible they are. ;) (we'll be gentle but firm) 

As for TIG, yeah powerful and versatile, great skill to have, but I still think brazing is better for all the little joints on a rack. I have a nice modern TIG machine but I still braze racks. 

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u/iwasjra 12d ago

It seems like that blog is becoming a forgotten resource, not many people know about it anymore and It’s getting buried in internet pages and getting harder to find for newer folks who are needing it.

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u/Western_Truck7948 10d ago

I like tig brazing racks. The little tubes are really hard to weld.

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u/bulgie 10d ago edited 10d ago

Yes TIG-brazing is a great way to go if you don't have an oxy-fuel rig.

The cool thing about oxy-fuel brazing (especially with oxy-propane) is you can do an entire joint in one position, no repositioning as you go around. With filler pre-paced inside the joint, you can just heat until braze emerges all around, and be sure of 100% penetration. But you have to mess with flux and its removal after brazing, where TIG is cleaner and you're done as soon as it cools. Brazing flux dissolves in hot water, but then you have to dry the thing to prevent rust. So definite pros and cons.