Anyone experienced with tig brazing?

enginebuilder · Jun 11, 2008

I have a manual transmission case that has a small crack, No structural issues, it simply leaks a little gear lube. normally I wouldn't bother , except this in a race car, and if oil drips on the exhaust (smoke) you're going to the pits due to a black flag. Not quite sure I'd trust JB weld or similar due to proximity of a very hot exhaust pipe. Tig brazing would likely be the easiest repair, but I have never attempted it before. Plenty of torch brazing, mig, tig and stick.
I thought by tigging, I might be able to due in small sections and not have to disassemble the whole thing.

Any advice from you more seasoned fellows?

TIA
Jim

joebass · Jun 11, 2008

Silicon Bronze rod at half the amps you normally would use. Flows like butter, and it should look just like a TIG bead but it will be a gold color.

Mud · Jun 11, 2008

Yes, what he said. Silicon Bronze (AKA Everdure) is funny stuff. If you lay it on like O/A brazing, it works just like brazing and flows like butter. If you turn the heat up, it's like tig welding and makes a bead that combines the parent metal and the rod.

TonyOW31 · Jun 12, 2008

I presume that the case is not aluminium because you want to braze it?
So when brazing with tig, do you use AC or DC?

macona · Jun 12, 2008

I had never dont it before until recently. I had a chuck guard for my lathe that had a chunk broken out so I tigged it with silicone bronze. Worked really well. Amazing how easy it sticks to the cast.

MilGunsmith · Jun 12, 2008

TIG Braze Cast Iron

Do you use any flux or flux coated rod? What amps? AC or DC? What type of tungsten? Rod source? I have brazed with O/A, but we dont have the O/A tanks at work, due to the Safety Office. I was able to get a TIG unit past them with some difficulty. I work in what is considered an explosives building, even though we only work with small arms ammo, they treat us as if we were working with Nitro.

jamscal · Jun 12, 2008

I've done it only for testing purposes, just to see if I could do it.

I believe I used DC, but I was brazing steel. AC is only beneficial for it's cleaning action on aluminum (and Magnesium?).

I tried it with the flux on and got a mess. I scraped the flux off and it worked better. The Argon is your flux, I suppose.

I kept the amps low and the heat on the steel. The rod would vaporize with too much heat.

It's been awhile, so hopefully I remembered the above correctly.

Hope this helps,

James

Mud · Jun 12, 2008

MilGunsmith said:
Do you use any flux or flux coated rod? What amps? AC or DC? What type of tungsten? Rod source? I have brazed with O/A, but we dont have the O/A tanks at work, due to the Safety Office. I was able to get a TIG unit past them with some difficulty. I work in what is considered an explosives building, even though we only work with small arms ammo, they treat us as if we were working with Nitro.

NO flux, DC, 2% tungsten, most any welding supply SHOULD have the rod - 3/32 dia. Set up just like welding steel but flow the rod in when the parent material turns red but before it begins to flow. Practice on some steel first - works the same way. Because you are using less heat, you'll get less spitting and etc. from the cast iron impurities. Very handy for joining thin steel to thick steel without melting the thin steel - e.g. header tubes to flanges.

enginebuilder · Jun 12, 2008

Thanks for the info guys, I'm off the the welding store for some silicon bronze rod. I'll try and post results this evening

Jim

Mud · Jun 12, 2008

I should have added - don't try O/A brazing rod. It will blow up and make a mess of your tungsten. Good luck!

enginebuilder · Jun 12, 2008

Update!

OK, got the silicon bronze rod this morning, came home cleaned the case ground out the crack and had success! Its not the prettiest weld ever but it is pretty easy to do.

Here's the crack magnafluxed:

and heres the weld:

Thanks for the advice, without it I likely would have tried the brass rod and gotten pissed off :willy_nilly:

Saturday night will be the test to see if it leaks or not

Jim

Pauls · Jun 13, 2008

Would it be better to grind out most of the crack then make the tig repair?
This would give more area for the silicone bronze to bond to.

MechWerks · Jun 14, 2008

I wouldn't bother putting a bolt in that lug...it isn't going to last if bolted down and the leak will get real bad them. Only using three bolts will most likely give you some clutch problems eventually...time to hunt down a new transmission or case.

eKretz · Jun 15, 2008

Pauls, he said he ground out the crack in the post directly before yours. I am inclined to agree with MechWerks about the repair failing to hold though. Hopefully we are wrong.

MechWerks · Jun 15, 2008

I am not guessing...have the experience.

IOWOLF · Jun 20, 2008

I bought some S/Bronze a week ago its about a $1.50 per stick for 3/32.

Its the best stuff since Nickle rod, IMHO.

anchorman · Jun 24, 2008

I take it, because the heat is so localized because of the tig torch, that you don't need to preheat?

Also is actual tig welding of cast iron a problem because of the impurities? I was thinking of trying 308L stainless. Has anyone had any success with that?

jon

macona · Jun 24, 2008

Tig brazing does not get nearly as hot as tig welding. So preheat is not as necessary.

I have tigged cast using some supermissle rod. Not fun. The cast burns away is about the only way I describe it. I think the carbon vaporizes and leaves the remaining iron which then balls up under the arc. Its really hard to avoid undercutting at the edges of the weld.

I have had not so good luck using 308 or 309 welding up steel, it absorbs the carbon and becomes harder than heck.

Supermissle rod made by Harris is supposedly a 347 stainless rod. Welds just about anything and you pay for that ability when you go to buy it. Most welders will keep a few sticks around just in case. Its available in Stick Electrode, mig wire and tig wire, though I have only seen stick rods of the stuff. I have maybe a dozen rods of the stuff. When I tigged with it I smashed the flux off.

MetaRinka · Jun 26, 2008

anchorman said:
I take it, because the heat is so localized because of the tig torch, that you don't need to preheat?

Also is actual tig welding of cast iron a problem because of the impurities? I was thinking of trying 308L stainless. Has anyone had any success with that?

jon

a lot depends on the grade and type of cast iron, Some cast irons are considered unweldable due to inclusions such as sulfur, lead or manganese.

The actual physical welding of cast iron is relatively easy cast iron is very fluid by nature (which is why they use it to cast things) the puddle will flow in real nice.

Cast iron however by the nodular nature of the cementite is extremely prone to cracking due to thermal expansion. Hence the weld 1" and peen like crazy (usually having someone follow behind you and peen. Or preheat the entire casting and weld at the preheat temperature and allow the part to slowly cool (usually too much distortion for engine work)

I've tig brazed cast iron DCEP, you reverse the polarity you would normally use so that the majority of heat goes into the tungest (also use an electrode one size larger than you normally would.) I've also tig brazed my share of copper and brass and bronze this way. I've also hard faced cast iron but overall it's an annoying metal to work with due to with it's attraction to cracking.

metlmunchr · Jun 26, 2008

My dad's shop used to do a lot of small stainless sheet work for a plant here that made rayon and nylon. He had one man who fit every part of the description of master sheet metal mechanic who always did all that work.

That guy was one of the world's greatest promoters of Everdure, or Everdew as he preferred to call it. On sheet thickness stainless he'd often use a carbon rod in a stick electrode holder to create the arc instead of using TIG for the arc. He said he could get what he called a "softer" arc with the carbon rod, and that it allowed him to control the puddle and buildup better.

When I was in high school, he was making a couple thousand fume extraction devices for use on rayon spinning machines. All 304 SS with tubes to hook up to extraction hoses and spring loaded hinges to allow access for rethreading the spindles. He showed me how to make the Everdure joints and within a couple hours I was getting results that looked surprisingly good. Not due to any great skill on my part, but rather just a process that was ideally suited to the work at hand.

I attended his funeral a few months ago and it brought back memories of my summer as an "Everdew welder" from 40 years ago. It also made me wonder if anyone still uses a carbon rod for the arc in this type work, because I've never seen anyone else use it, or mention it as a common thing.

Anyone experienced with tig brazing?

Stainless

Aluminum

Diamond

Stainless

Diamond

Stainless

Stainless

Diamond

Stainless

Diamond

Stainless

Plastic

Cast Iron

Diamond; Mod Squad

Cast Iron

Hot Rolled

Titanium

Diamond

Cast Iron

Diamond

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