On 09/13/2010 06:52 AM, Winston wrote:
On 9/12/2010 3:16 PM, Tim Wescott wrote:
Needed to join two pieces of mild steel today, with minimal bead and
as strong or nearly so as the parent metal.

(...)

My understanding is that one must provide a lap surface that
is some largish multiple of the material thickness.
Ferinstance I would go with say, 0.5" wide lap, joining
0.03" thick material.

Yes, I was going off my soldering instincts, so there's about 1 square
inch of area to stick some 1/8" plate onto a 1/16" wall tube.

See, for example lugged frame construction in bicycles.

Actually I've seen frames that are brazed with no lugs. The claim was
that if you're hand brazing you can do a fillet to get all the strength
you need.

(Lugs were for hairy-knuckled factory workers in England and Italy who
stuck whole frames into furnaces).

I don't know if that's for real, but they were certainly the bees knees
for a while back in the 1980's.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Mon, 13 Sep 2010 09:20:28 -0700, Tim Wescott
wrote:

On 09/13/2010 06:52 AM, Winston wrote:
On 9/12/2010 3:16 PM, Tim Wescott wrote:
Needed to join two pieces of mild steel today, with minimal bead and
as strong or nearly so as the parent metal.

(...)

My understanding is that one must provide a lap surface that
is some largish multiple of the material thickness.
Ferinstance I would go with say, 0.5" wide lap, joining
0.03" thick material.

Yes, I was going off my soldering instincts, so there's about 1 square
inch of area to stick some 1/8" plate onto a 1/16" wall tube.

See, for example lugged frame construction in bicycles.

Actually I've seen frames that are brazed with no lugs. The claim was
that if you're hand brazing you can do a fillet to get all the strength
you need.

(Lugs were for hairy-knuckled factory workers in England and Italy who
stuck whole frames into furnaces).

I don't know if that's for real, but they were certainly the bees knees
for a while back in the 1980's.

There is special brazing rod for "fillet brazing" that has a broader
"plastic range" so it doesn't all melt and run away at the same time.
Generally done with gas flux too - the gas bubbles through the flux
before getting to the torch. Nasty stuff, but it does a beautiful job.

Nickle silver brazing rod comes to mind.
GasFlux is Methyl Borate based and you should wear cobalt blue welding
lenses to better see the green flame.