Deflux/Derust before Reflux?

[ToddFarr]

This might be a silly question, but this is my first jigged frame so here it goes.

I'm getting ready to tack the frame, after I tack and check alignment do I need to deflux and derust everything applying new flux before I finish all the brazing. Or Do I just throw more flux on the cool hardened flux and continue on?
Also, I am planning on doing the front and rear triangles separate, so when you deflux everything in a water bath the BB area gets awfully rusty. On my last frame I spend hours removing all the rust inside and outside before I refluxed and brazed on the chain stays. Looking through some Sach's photos today in FNL, it seems the outside of the bottom bracket is pretty rusty although the chainstays are getting ready to be brazed.

Thanks in advance as always -Todd.

[e-RICHIE]

Assemble, tack, check, and braze atmo. Add more flux after the tack is cooled and checked, but before brazing. But don't linger between operations. There's a small window of time you can waste and not be concerned about the original flux going awry. But since you are new, don't waste it.

[e-RICHIE]

On my last frame I spend hours removing all the rust inside and outside before I refluxed and brazed on the chain stays. Looking through some Sach's photos today in FNL, it seems the outside of the bottom bracket is pretty rusty although the chainstays are getting ready to be brazed.

Heh? There's no rust on my parts. I brazed that joint 30 minutes after I shot the pics. And the stays/shell had the requisite 3.9992228 pounds of flux on them atmo.

[ToddFarr]

I was referring to this picture here, and more so talking about after the front triangle is all finished and the rear triangle is prepared to be brazed.

IMG_3266 | Flickr - Photo Sharing!

I am assuming the inside is cleaned and cleared from rust, but does that rust on the outside surface affect the flux in a negative way?

I hope this clarifies my comment

-Todd.

[e-RICHIE]

There's no rust there atmo. After the main triangle is soaked and worked on, some of the areas that are untouched are discolored from the drying process. But that's not rust. And regardless, the brazing goes inside the c/stay ports so in theory the exterior is not part of the equation. But if there was rust, or oil, or gazpacho, I would not be going forward until it was clean room clean. PS the gazpacho reference was levity.

[ToddFarr]

So you are saying that orange on the BB shell is not iron oxide? What is it?

[e-RICHIE]

So you are saying that orange on the BB shell is not iron oxide? What is it?

I dunno what it is, but I am saying I don't care, and it's not affecting the work atmo!

[ToddFarr]

Thanks everybody, It was a great read through and thank you for offering up the information. Do you guys use a flap wheel to mechanically clean the inside of the tubes or?

[e-RICHIE]

Thanks everybody, It was a great read through and thank you for offering up the information. Do you guys use a flap wheel to mechanically clean the inside of the tubes or?

I have never touched the inside of my tubes except to de-burr them after the cuts are made atmo. They are, however, liberally fluxed.

[dbohemian]

Thanks everybody, It was a great read through and thank you for offering up the information. Do you guys use a flap wheel to mechanically clean the inside of the tubes or?

Yes, I de-grease the entire tube and mechanically clean the first half inch or so. Even though fluxes can sometimes eat through the heavy oxide there why put them through that? I want to give every opportunity to build a small internal fillet if possible and prevent contamination. It takes about 2 minutes per tube. Flap it my man.

[Eric Estlund]

I abrade the surface at the ends of all the tubes where I want filler to go, inside and out.

Flap wheel? Sounds like and extra SKU to inventory and $ to spend.

[Eric Estlund]

PS- I loved that little drill, but when it decided to ground through my arms/ chest and the pedestal I decided to let it go.

[edoz]

I abrade the surface at the ends of all the tubes where I want filler to go, inside and out.

Flap wheel? Sounds like and extra SKU to inventory and $ to spend.

I do the same thing with a Dremel and a piece of 1/8" tig rod to tape the 80 grit to.

[afwalker]

That is every bit as good as a flex hone
andy walker