Tig Weld what went wrong and whats next

[MountainBuck]

The chuck on my wood lathe spun off and hit the ground cracking it.

I decided to try and tig weld it. I used my Klutch DC tig welder at about 60 amps. The weld looked really good after but then I decided to grind it to make it smooth again. This uncovered the porosity. I realized that it is a cast piece and I should have heated it before trying to weld it. I did add filler metal.

Here is a picture of how it looks now. The porosity where the crack was is circled in green. I did hear it cracking after finishing one of the welds.

So where do I go from here? Should I use it? Can I fix it? Should I trash it?

Thanks in advance!

 

[CincyFlyer]

Cast iron can be problematic to weld; with experience, it can be done. But for something that spins and can cause injury if it breaks, I'd take it to a welding shop with experience (myself, I would have preheated to really darned hot, and used a very high nickel filler) or replace it.

 

[sd455dan]

The chuck on my wood lathe spun off and hit the ground cracking it.

I decided to try and tig weld it. I used my Klutch DC tig welder at about 60 amps. The weld looked really good after but then I decided to grind it to make it smooth again. This uncovered the porosity. I realized that it is a cast piece and I should have heated it before trying to weld it. I did add filler metal.

Here is a picture of how it looks now. The porosity where the crack was is circled in green. I did hear it cracking after finishing one of the welds.

So where do I go from here? Should I use it? Can I fix it? Should I trash it?

Thanks in advance!

View attachment 527398

No expert here but would think you would need to determine whether that is cast steel or some form of cast iron...

If a small amount of the surface is drilled cast iron will be very fine almost like powder where cast steel will give actual shavings.
a tap with a hammer will have a ring with cast steel and cast iron will be more like a dull thud.
lastly when you ground it down were the sparks dull red or amber, a sign it is cast iron - which is much harder to weld with out problems.

What type of filler were You using? Also if it was a gas coverage issue did you use a gas lens - it might help


i am sure some with a whole lot more knowledge will be here to help soon.

 

[yomax4]

60 amps would not repair this chuck but I need to know what you used for filler metal to start.

 

[MountainBuck]

Thanks for the replys!

Tap with hammer and real dull thud.

Grinding did not like to spark at all but if it did, I would call it deep red. But with a small dremel it didn't spark at all. Only with the 4 1/2" grinder did I get anything.

Filler rod was ER705-2 1/16. Really thought I got good penetration. Here is another picture of the underneath side

The green circle shows the edge of one crack and the red circle is where I hit a crack but didn't use any filler wire. It balled up nicely.

No gas lens.

 

[sd455dan]

Very likely Cast Iron.

some fillers that might work, 309 stainless, Hastelloy or Nickel rod, cast iron mig wire, or cast iron rod.

There is Brazing rod to.

Don't think ers70 of any type will work well for this... Most likely going to want some sort of pre- heat to

Actually surprised how well it appears to have gone

But I would not trust it for a high mass rotating part that you would be standing next to it.






edit after a bit more thought- Buy a new chuck the danger of what could happen during a failure , is not an acceptable risk.

 

[Shield Arc]

I bought some of this A2 Aluminum Bronze a few years ago. I've been meaning to try my luck with it on cast iron. But haven't done it yet.
1/16" A2 Aluminum Bronze Tig 36" Rod - 1 Lb - AWS A5.7 ERCuAl-A2 | eBay

 

[woodlandfarms]

So this thing is spinning at 1500 RPM or so.. I do not want to be the safety police but I think I would get on Amazon and order a new one. I cannot imagine every getting this thing true.

 

[Gary Fowler]

Without getting into the repair or replace argument, I think your welding problem is likely due to oil contaminated steel. I really doubt that the part is cast iron and more likely cast steel unless it is a really cheap lathe.

Any way regardless of the parts metallurgy, you will have to grind out the old weld, preheat the whole thing hot enough to burn off all the oil and then re-weld it. I would use a stainless steel rod (any grade is better than the ER 70S-2 that you used). Stick welding would likely produce less porosity than TIG. Be sure to completely grind out all the old weld because if you leave even one bubble of porosity it is going to spread all thru the new TIG weld.

 

[3Ts]

At what speed do you spin it? The 1500 rpm seems on the low side for some turnings, mine will do 3200 rpm. Also, be sure you re-balance it before you use it. It may be better to replace since you'll be standing right next to it or in front of it if it decides to come apart again. Some things are not worth repairing in my opinion.