Mig brazing

all i can see is ...the first time you have the wire burn back to the nozzle ......youve a ruined tip............the wire would crush in the rollers and maybe ...ravel up in the tube .

all the best.markj

mm, it's OK, not as strong as brazing and not as nice a weld (though that may be down to operator error) but I've used it, again with argoshield, with satisfactory results on pump bodies and the like.

YMMV

Put it this way, the small amount of "brass" mig wire I had ran out a couple of years ago, and haven't missed it, if I had more brazing to do next week I'd just refill the oxyacetylene tanks.

I have done silicon bronze brazing using a Lincoln SP125+ welder. This is a little 115 volt machine and the wire I used is .025", .625mm. Argon shielding gas and the machine set to maximum voltage. My little machine has just barely enough power to run this wire. But pre-heating the steel I used it on made it work much better. Eric

.I saw it done at a local demo and went out and bought a big coil of wire. As MarkJ has reported, my spool went all over the place exceot where it was intended. I had burn backs, squashed wire, bird's nests and who knows what.

Obviously, some people can do it but maybe the welding equipment was superior to Mark's and my BOC 130 amp job which was running on argoshield.

As the wire obvious;y deformed, the question was what was causing the trouble. Were the rollers wrong? was the sleeving wrong? was the spring sheathing wrong? or were the nipples the wrong size? Or was it me?

Now I was a certified welder. And I felt that I needed to be certified!

Norm

May only work well with a new-ish liner for the torch. ally and bronze are going to be far more sensitive than steel to friction from an abraded liner.

Mark Rand RTFM

. Mark, Agreed but I did and failed! But brazing(?) is really a method for joining disimilar metals. Ok, I am in for it again but the vehicle body people will go for spot welding wherever they can, count the spots according to Thatcham or when all else fails 'stitch' with steel wire in a decent MIG/MAG welder.

I've just had =A37+K of body work done on one of the Mercs and nothing was brazed.

'Thatcham' is the RTFM

Cheers

Norm

On or around Thu, 23 Oct 2008 23:10:06 +0100, Mark Rand enlightened us thusly:

ah, now, there I made a good discovery. As you may know, I'm in the cycle industry. Best stuff ever for torch-feed liner is indexed-type teflon-lined bike gear cable outer casing. Just the right size, stiffer than the normal stuff and thus less prone to kink. It's a very slow helix multi-wire casing, not like the normal brake type ones with a fast single helix, and likesay teflon liner.

I can supply lengths, if anyone wants :-)

Tip condition is probably relevant as well...

The issues with wire-feed and snarl-ups and so on sound very like what you get with alu mig welding - everything's got to be in A1 condition to feed alu...

On or around Thu, 23 Oct 2008 15:56:27 -0700 (PDT), ravensworth2674 enlightened us thusly:

Some metals aren't supposed to be welded. e.g. cro-mo alloy cycle tubes - bronze welding doesn't get it so hot and doesn't spoil the structure.

Austin, this is another situation where workshop manuals etc are being condensed to fit a format where 'one liners' are supposed to really help. Of course, your comments are quite correct. I didn't want to go into the realms of high strength low alloy steels which crack on gas welding. And , of course, the morgues are full of those who are foolish enough to do DIY welding! We crack a damned sight quicker. Have you ever seen line cracks running down in parallel to a gas weld?

Thank you for the opportunity to try to get the warning across

Cheers

Norman

Brazing or silver soldering sheet with a scarf joint or backer will give a stronger joint than welding if both are done properly. Unfortunately the MOT inspectors are ordered to fail brazed joints on structural components. The sole exception being where the car was originally manufactured using brazing and the repair joint can be directly compared with the original work

Of course, some of the AHSS steels being used for car bodies these days can't be welded without loosing their strength...

MIG-brazing seems to me to be the worst of all worlds for most things (pretty joints with no possibility of fusion and no guarantee of mechanical joining), but I guess it's ok if done properly or where bondo would be the alternative.

But you already knew all that :-)

Mark Rand RTFM

Have a look here

On or around Sun, 26 Oct 2008 00:27:13 -0700 (PDT), John enlightened us thusly:

hmmm. interesting.