I have this lot of '96 mausers that I bought years ago from the cat who acquired the last of Kimber's endo. The bridges were shaped with a belt sander. Or should I say raped? They were obviously discards with mount holes every which way, some tapped, some not. The holes are not a problem so much but tigging a pad over the bridge to get enough thickness to do something with has been hallucinogenic. First off, there is nothing 'wrong' with my setup. Checking the arc on a copper bar, a stainless bar, a tool steel bar, and an A36 bar shows nothing out of whack. But! in a short time the parent metal begins to emit sparks that fly up and contaminate the tungsten using Tartan G filler (or any other filler) that I try. In areas, the horrid bubbles arise to cause full stop. I've tried every flavor of tungsten to no avail. I've reversed polarity and even gave AC a shot. These actions have been thoroughly deoiled in caustic soda then scrubbed with hot water and detergent. I'm guessing that the casing has something to do with this (?) and I've picked a few bits here and there about using a large lens to obviate this. Any actual knowledge? All I know is that they do not behave like anything I've welded before except aluminum that's been in saltwater for twenty years.

Sounds like you are overheating the steel. Try pulsing your weld to minimise the heat input.
Don’t let the tip of your filler wire scale up in between passes, keep it in the gas shield until it cools or snip it off. That’s where the contamination starts, along with not enough post flow.
I have had this problem before, but since improving my procedure I’ve eliminated all porosity.
I do lots of bolt jobs and weld repairs on 98’s, but never on a ‘96.

Sounds like there is a lot of carbon or some other element that doesn't like to be melted in them. Send me one and let me try it.
Actual knowledge; no. I have used those, but never welded on one. 96 bolts; welded plenty of them.

I've got some indirect knowledge, not actual experience myself.

I had a Remington rolling block receiver ring welded up to a thicker dimension, very similar to what you're doing. First guy I had try it, had some kind of poor welds, luckily gave up before he ruined it. Took it to a really good TIG guy, and he worked on it and experimented while I watched, and we talked strategy of how to make it work.

The problem was like you stated, he would get going and get a decent puddle, and all of a sudden out would come boiling crud, contaminating and sputtering and exploding. He told me that was "carbon precipitation" from the excess carbon in the case hardening. His approach was to use pulse, to vary the heat going into the weld, and use the foot pedal control to back off the heat when the carbon started to boil out. He would do small arcs and circles with the torch, and he was able to drive the carbon out to the side of the puddle, and kind of dump it off the side of the weld. He had a lot of skill to manipulate the puddle to move the carbon to one side. When the carbon would stop boiling out, he'd go on with the weld, and when he finished a pass, he'd grind off the carbon slag pile before laying another bead alongside, over where he had just dumped the carbon. If you don't have pulse, you could experiment with reverse polarity, as you have already done, but that will of course eat the tungsten up and could overheat the torch. Or, use the foot pedal to manually pulse to reduce the heat in the workpiece. On both my TIG machines, I can also mess with the waveform, to change the heat. I haven't spent the time experimenting and with the manual to know how, yet.

That’s exactly what I do, pulse with the foot pedal.
With each pulse feed the wire in, back off then go again.
Do short runs, walk away and let it cool then go again.
Control the heat and you shouldn’t get any carbon precipitation.

I've had some luck welding nasty stuff by reducing the gas flow. In a calm indoor room with a large lens the gas flow can be turned way down and this seems to let crud pop or float out of the bead easier.

2¢

Thanks for all the replies. As luck would have it, my pedal just died and while I'm waiting for a new one I'm also ordering a lens and wide pyrex cup. So it's off to barreling for now...

Those Furick lenses are next level.

quote:

Originally posted by metal:
Those Furick lenses are next level.

Exactly what I ordered from Amazon. Thanks.

Your rolling block was wrought iron; I tried to weld on once many years ago, but don't have the time now.
They are full of slag like grain in wood; that is want wrought iron is. But that can't be the problem with a 96 Swede.

Maybe someone put linseed oil on it.
That would cause havoc for any welding in the future.

Could be the caustic you cleaned with. Sodium can cause all kinds of problems welding!

If it isn't getting blued the absolute best filler rod for tramp metals is Brutis from Rockmont

quote:

Originally posted by ted thorn:
If it isn't getting blued the absolute best filler rod for tramp metals is Brutis from Rockmont

Ted, I was using Tartan G tig rod that I see is no longer available made by the same people back when they were Nassau, I believe, or some other name that I can't remember because it was YEARS ago. I've been to their site and plan on calling them for some guidance. Because I finish bolts bright, I've been using 309L because it welds any steel to just about any other steel, including cast iron and flows beautifully. I have a Columbian vice that broke thirty years ago and I welded it up with 309, hasn't missed a beat since. Didn't even pre-heat.

And as far as bluing goes, does it rust blue?

Thanks for the Reply.

I had a Columtain vice once; Crack.
(That is a joke and a little play on words for those AR members who don't get jokes)

quote:

Originally posted by copperlake:

quote:

Originally posted by ted thorn:
If it isn't getting blued the absolute best filler rod for tramp metals is Brutis from Rockmont

Ted, I was using Tartan G tig rod that I see is no longer available made by the same people back when they were Nassau, I believe, or some other name that I can't remember because it was YEARS ago. I've been to their site and plan on calling them for some guidance. Because I finish bolts bright, I've been using 309L because it welds any steel to just about any other steel, including cast iron and flows beautifully. I have a Columbian vice that broke thirty years ago and I welded it up with 309, hasn't missed a beat since. Didn't even pre-heat.

And as far as bluing goes, does it rust blue?

Thanks for the Reply.

Brutis is high nickel and stainless....it won't rust

quote:

Originally posted by dpcd:
I had a Columtain vice once; Crack.
(That is a joke and a little play on words for those AR members who don't get jokes)

More like a dumb-arsed typo!