How do I machine this feature on this part?

[MyLilMule]

I have a Hobart Handler 175 mig welder. I was having some porosity issues.



And yes, I know how to run this machine, I am a certified welder and have double checked everything I can, outside getting a new bottle of gas. Polarity is correct, etc. It's good Lincoln Electric wire. Parts are clean. Gas is C25.

I believe I have narrowed the problem down to this aluminum part:



It's the connector between the machine and the gun. It's aluminum and the gun port is brass. Galvanic corrosion. Yay. This machine is older, and I have never had this apart.



I am certain this is where the air leak is coming from. The aluminum corroded to the point of deep pitting. The O rings are dead - I tried replacing them first to no avail. Unless I plan to make this machine a dedicated flux core welder, I need to replace the connector and the gun. The gun is easy. The connector, not so much. It isn't available anymore. Best as I can tell, after searching the deepest bowels of the interwebs, it is nowhere to be found.

In any case, I have re-engineered this part. I'm pretty sure, even as a noob, I can make this on my Bridgeport (when it is operational again). My specific question is, how can I machine this little feature? It has to be there. I think I can machine the rest, order of operations not withstanding. But what kind of a tool, besides a hand file, would I use to machine this little lip?



I didn't include all the dimensions on this drawing, but you should be able to tell what I am talking about (I hope). It's .125 wide, and about .065 deep. And there's a lip thats .065 wide at the outermost part.

 

[extropic]

You can use a Woodruff Key Cutter. Get a .125 wide cutter. Done in one or two passes.

 

[MyLilMule]

You can use a Woodruff Key Cutter. Get a .125 wide cutter. Done in one or two passes.

Thanks! I hadn't thought of that.

 

[extropic]

I want to comment on your asking the question in such a comprehensive way.

It's easier to offer recommendations when the issue is so well described.

Here is an alternative rework option. What do you think about opening up the damaged area and pressing in an aluminum (or stainless) sleeve?

What material did you intend to make the replacement block out of? Using steel (or stainless) might eliminate the galvanic issue. I would also consider a light coat of grease on the gun/connector to act as an oxygen barrier and minimize the corrosion issue.

 

[Cadillac]

Depending on how much wire youve put through the gun the liner does go bad.

 

[MyLilMule]

Depending on how much wire youve put through the gun the liner does go bad.

I replaced the liner, too. I also did the Abom roll of my C25 tank. No joy,

 

[MyLilMule]

Here is an alternative rework option. What do you think about opening up the damaged area and pressing in an aluminum (or stainless) sleeve?

What material did you intend to make the replacement block out of? Using steel (or stainless) might eliminate the galvanic issue. I would also consider a light coat of grease on the gun/connector to act as an oxygen barrier and minimize the corrosion issue.

I thought about chucking it in my 4 jaw on the lathe and boring out the hole (mill is not operational as of this writing), but there's not a lot of wall thickness around that bore. I might give that a try.

As far as replacement material, not sure. The original is cast aluminum. Not sure what 175 amps will do to that grease. Although I would think there would have been some kind of anti-corrosion material placed on it originally, like the stuff used in electrical panels when using aluminum wire. I was just going to do some research on what would be the best choice in aluminum.

 

[addertooth]

I would machine the hole in the aluminum bigger, and sleeve it with brass. Then replace your two O-Rings on your torch. Porosity is due to the gas not fully "protecting" the hot weld.

 

[MyLilMule]

I would machine the hole in the aluminum bigger, and sleeve it with brass. Then replace your two O-Rings on your torch. Porosity is due to the gas not fully "protecting" the hot weld.

Thanks. I replaced the O rings. And you probably missed the part where I stated I am a certified welder. I know what shielding gas does.

 

[extropic]

@MyLilMule, that grease you use on aluminum wire would be perfect. The grease is unaffected by the current. The current flows at metal-to-metal contact.

Regarding relining the existing connector, consider the using K&S Precision Metals thin wall tubing. It's widely available at hobby shops, Ace Hardware (and the like) and they also sell direct. Tubes are available in aluminum, brass, copper and stainless. McMaster also carries a considerable assortment of metal tubing, available in short lengths.

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