[Chips O'Toole]

I'm new. I know very little about welding. I use a MIG, and so far I've only welded carbon steel and stainless (bracket on a nerf bar).

I joined because I want to learn more. Right now I have a job I don't know how to handle.

I have a motor with a broken base. I got it on Ebay. I got a refund because of the damage, but now I'm stuck with the motor. No one will buy it. I am wondering if I can use MIG to fix it. I don't want to use a method that requires heating everything super-hot with a torch, because I don't want to damage things like insulation and paint. Also, I don't have an acetylene rig!

I saw a video of a guy welding cast iron with TIG, without much of a preheat. That surprised me. If I had his skills and his tools, this job would be a done deal. He didn't use blankets, and he didn't braze. He used 99% nickel rods.

Since then, I've Googled around, and I've learned that some people manage to weld cast iron with MIG. I'm wondering if the job I have to do is suitable. I don't mind buying a different type of wire. It would be worth it just to learn to weld cast iron.

12-01-16 mitsubish motor foot broken from craigslist.jpg (30.51 KiB) Viewed 1326 times

I'll put up a photo. It's pretty obvious what has to be done. I would say the metal is around 3/8" thick.

[Otto Nobedder]

Half the bolt hole is there. I assume the broken off bit is missing?
I'd make a matching piece to surround the hole from whatever steel I had on hand, and braze it on. This lug does not see tension loads. You only need the "other half" held in place so the bolt holds it down.

Steve S

[Chips O'Toole]

Half the bolt hole is there. I assume the broken off bit is missing?
I'd make a matching piece to surround the hole from whatever steel I had on hand, and braze it on. This lug does not see tension loads. You only need the "other half" held in place so the bolt holds it down.

Steve S

Thanks for replying. As I noted, I don't want to braze it because I don't want to heat the motor casing with a torch and melt the insulation on the windings and so on.

I do have the missing piece of cast iron.

[Otto Nobedder]

Half the bolt hole is there. I assume the broken off bit is missing?
I'd make a matching piece to surround the hole from whatever steel I had on hand, and braze it on. This lug does not see tension loads. You only need the "other half" held in place so the bolt holds it down.

Steve S

Thanks for replying. As I noted, I don't want to braze it because I don't want to heat the motor casing with a torch and melt the insulation on the windings and so on.

I do have the missing piece of cast iron.

I see. If you had serious brazing experience, this would be a non-issue, "but"...

The broken lug is a minor issue, if you have a solid base to mount it to. You could soft-solder it. MIG may work fine, though you risk cracking as it cools since I doubt you want to preheat . Epoxy is a viable option, since once it's bolted in place the washer on top should eliminate relative movement.

People tend to overthink these things. Look at it's purpose, and realize that if a strong connection was required, that part would be forged, not cast.

Steve S

[Chips O'Toole]

I have read that it's possible to use stainless wire and a MIG welder, after warming the cast iron to about 100 degrees. Supposedly you can do it in short bursts, letting the work cool in between and peening the welds. I was wondering if this would work.

I don't know a whole lot about peening. I do have a needle scaler and of course, a ball peen hammer.

[Otto Nobedder]

The needle scaler is the best peening tool available to the average guy.

I'd say to give it a go as you've outlined. The worst that can happen is you have to do it again, so nothing lost.

Steve S

[exnailpounder]

The needle scaler is the best peening tool available to the average guy.

I'd say to give it a go as you've outlined. The worst that can happen is you have to do it again, so nothing lost.

Steve S

Air chisel works great too.

[weldin mike 27]

You have enough meat next to the broken area to use a bolt and a hold down clamp. (a piece of flat bar) As you are not confident in repairing this, that is what I would do.

[Jim FLinchbaugh]

You have enough meat next to the broken area to use a bolt and a hold down clamp. (a piece of flat bar) As you are not confident in repairing this, that is what I would do.

+1
over thinking

[Otto Nobedder]

OTOH, a welder wants to weld it. I see no harm in giving it a go, and maybe some self education in the process...

Steve S

[Chips O'Toole]

OTOH, a welder wants to weld it. I see no harm in giving it a go, and maybe some self education in the process...

Steve S

Fixing the part is not the big priority. There are various ways to get around the foot problem if I want to use the motor. I just want to see if it can be done with MIG, without preheating the part so much it destroys the windings.

[PeteM]

Turn it up side down?

[Chips O'Toole]

I may give it a try today. If it works, I'll post photos and say I knew it would work all along. If it doesn't, I'll blame everyone here for giving me bad advice.

[Otto Nobedder]

I may give it a try today. If it works, I'll post photos and say I knew it would work all along. If it doesn't, I'll blame everyone here for giving me bad advice.

Sounds like a solid plan!

Steve S

[Chips O'Toole]

Now I can't find the piece that broke off.

[Poland308]

Now it's a real project. Build it up and re drill.

[Chips O'Toole]

I'll just pile 4 pounds of weld on it and sculpt a new base with a rotary burr!

I'm sure the part is here somewhere. You don't forget throwing out something you really wanted to keep.

[Chips O'Toole]

Great news! I went outside and dug through my shop trash and found my bench brush, which I apparently threw out last week.

No cast iron, though.

[Ruark]

There's enough acreage left next to the break to just drill another hole and use that one.

[Chips O'Toole]

There's enough acreage left next to the break to just drill another hole and use that one.

Not really. Maybe if you put a tapped hole in the motor and ran a bolt up through the base.

I found the missing iron in my kitchen. First place I should have looked.

[Chips O'Toole]

I want to think everyone for their help.

I think I actually succeeded in repairing the base. Notice I didn't say "welding" it. The mess I made is so sloppy, I'm not sure it even qualifies to be called a weld.

I used 308L wire. I had read that non-magnetic stainless was the thing to use. I heated the piece to somewhere above 100 degrees, according to the strange instructions I read elsewhere. Then I did what I ALWAYS DO 100% OF THE TIME. I started welding without turning the gas on.

I ground off as much of the spongy crap as I could and started over, with two small welds on the bottom side. I had the wire feed turned up, according to something I had read. What a mistake. I was only welding a few seconds, but I ended up with big globs again. Back to the grinder.

I beat the globs with a ball peen hammer and then ground off the excess. I never heard the "tinking" sounds you're supposed to hear when cast iron welds break. That's the main reason I'm posting this. I would like to know what went RIGHT. I can't understand why the welds didn't pop. Maybe because they're shallow? I only v'd out maybe 3/32", because I was afraid if I didn't leave some meat it would be hard to hold the pieces together while I welded. As it was, I had to use a Bessey clamp.

I ground off the new globs and did some more welding. Still too much wire, but no popping noises.

I removed as much excess metal as possible and tested the repair by yanking on it and beating it with the handle of the hammer. It's probably the worst weld in the universe, but it's aligned perfectly and will probably work well enough for the purpose of holding a motor down.

I may be able to clean it up some more if I can find the right rotary tool.

This went incredibly well, even though it looks like there is no possible mistake I failed to make.

[Oscar]

I would think that by now, you knowing your yourself, would have put a label on your MIG gun with a note to turn the gas on before squeezing the trigger.

[Chips O'Toole]

I would think that by now, you knowing your yourself, would have put a label on your MIG gun with a note to turn the gas on before squeezing the trigger.

You joke, but I was planning to do that today.

[Oscar]

Well kinda joking, but serious as well. I mean, it will only help you, right? Especially since you do it "100%" of the time. But don't "plan" on doing it today. Do it.

[Chips O'Toole]

I don't want to get in trouble with Zod.