help TIG brazing cast iron

[tapkoote]

I cracked a chunk out of a two belt pulley.
It' hard to replace as it uses two different belts,
one has a half twist for reverse. (it's on my garden tiller)
It is rather thin on the outer edge, so I hesitate to stick it.
One of my welding teachers liked to braze with his TIG torch,
but i never got a chance to ask
him about it. Wish I had now.
What kind of wolfram? Do I want a tip like for aluminum,
or a point.
I've got a lincoln 175 tig/stick, what kind of heat?
I've got an oven for preheat. 400*
With this silicon tig rod do i need the argon?
I read the brazing 101 thread it's great
thanks for any help
Pat

 

[NASTYZEN]

As far as I remember, you use the same settings as if you were to tig weld metal. Strait polarity, sharp tungsten, between 10 to 15 cfh of Argon. Pre heat is a good idea.
Personally, I would braze it with Oxy-Ace.
Good luck!

 

[readhead]

Tig and braze are two different processes that do similar things. Brazing would probably work better in this case. It will be a little easier to control.

 

[Zrexxer]

With this silicon tig rod do i need the argon?

Only if you want to keep your tungsten from burning up instantaneously.

 

[zkling]

Tig and braze are two different processes that do similar things. Brazing would probably work better in this case. It will be a little easier to control.

The op is referring to a process called tig brazing. It is similar to standard brazing but you use a tig torch to apply the heat instead of a flame torch.

OP I have done it a few times. Nastyzen is correct (as usual). Argon, DCEN, I personally use a flat tungsten, sharpened slightly only to stabilize the arc. You want the widest arc possible for brazing.

Can you post a pic of the part that needs to be repaired? I am having a hard time visualizing this. I have also used Nickel rod with the tig to build up small cast iron pieces. I would prefer that over tig brazing with Si rod for small parts.

 

[tapkoote]

The cost of acetylene is dear, I use it as a last resort.
My thoughts too on a broad tip, don't want to concentrate the heat.
I've tried before to post pictures but this computer doesn't like me.

 

[tapkoote]

Lets try again

 

[NASTYZEN]

I would then v that break a little and use Nickel rod. Your local welding supply should have those for tig. Or use an arc filler rod with stick welder.

 

[NASTYZEN]

Nastyzen is correct (as usual).

Thats not what she tells me.

 

[readhead]

Zkling reread my post and then read your response. I have been welding for 40 years and I know the differance.
To be more specific I was union trained and currently own a fab shop.
You can TIG with various rods and you can braze with various rods and have the same result.

 

[Zrexxer]

You can TIG with various rods and you can braze with various rods and have the same result.

That doesn't even make sense.

 

[welder4956]

One of my welding teachers liked to braze with his TIG torch,
but i never got a chance to ask him about it. Wish I had now.

As others have mentioned, the process is commonly called TIG brazing. The "official" term given for the process by the American Welding Society is "gas tungsten arc braze welding". But it is really just TIG welding with a low melting point filler. Brazing relies on capillary attraction of the filler metal into the joint between the two pieces of metal and usually uses flux for cleaning action. Capillary attraction into the joint does not occur when using braze welding and no flux is required.

What kind of wolfram?
The tungsten (wolfram) can be whatever you are currently using on steel - thoriated, ceriated, lanthanated.

Do I want a tip like for aluminum, or a point.
The tip is not critical, but I would lean toward a 15-20 degree angle with a flat on the end about 1/3 the tungsten diameter, and at least 3/32" diameter tungsten.

I've got a lincoln 175 tig/stick, what kind of heat?
40-60 amps works well. I like to use AC with high freq, but you can use DCEN also.

I've got an oven for preheat. 400*
400 F should be fine. I would leave it in there for at least an hour to give the heat time to soak through the part. You can get a 300 F and 400 F temperature crayon at the local welding supply to check the temperature of the pulley. If it drops below 300 F, put it back in the oven and bring it back to 400 F before continuing the weld.

With this silicon tig rod do i need the argon?
Argon is fine for this. You don't need helium or any gas mixtures.

 

[tapkoote]

I want to thank you guys for your help.
From now on any brazing I do will be tig.
I'll post the process on the brazing 101 thread, if it's still open.

 

[zkling]

Zkling reread my post and then read your response. I have been welding for 40 years and I know the differance.

From your original post, you clearly differentiate between braze (as usually referred to the gas flame process) and tig welding, there is no acknowledgment of the tig brazing process. I personally did not feel that you were clear or helpful enough so I elaborated.

The OP's initial post is clearly talking about the tig brazing process. He mentions nothing about the typical tig welding process. Therefore one can deduce that he is asking for help on the tig brazing process.

And before you state it, yes yes I know the differences between brazing (no melting of base metal) and welding (melting of base metal).

Tig and braze are two different processes that do similar things. Brazing would probably work better in this case. It will be a little easier to control.

To be more specific I was union trained and currently own a fab shop.
You can TIG with various rods and you can braze with various rods and have the same result.

I don't care if you welded the nozzles for the apollo mission. Then why didn't you provide useful information to the OP, since you are so skilled in the craft of welding?

I want to thank you guys for your help.
From now on any brazing I do will be tig.
I'll post the process on the brazing 101 thread, if it's still open.

Nice job, clean it up a bit and put it to use. Hopefully it is not a high speed application where the balance will be greatly effected.

 

[tapkoote]

Nice job, clean it up a bit and put it to use. Hopefully it is not a high speed application where the balance will be greatly effected.

This will be on a jack shaft and rum 1000rpm tops.

 

[NASTYZEN]

Great! Hope that fix will work for you. Isn't it great to be able to fix things for yourself.

 

[Bobhdus]

Lots of good responses. One of the things I consider to determine what process I use is if it needs to be preheated and how much. OAW welding in most cases will preheat while welding. The other side of it is if I need a more precise heat affected zone to keep from melting any seals etc... I may use GTAW. I was also taught in a cast iron repair class to use u grooves over v grooves But I never had a chance to compare the two grooves. In the real world of welding I usually wind up with two broken pieces and I have to bevel it the best I can to get more penetration.